altogether 84
countries/territories have announced vector-mediated Zika transmission.
→ In October-2016 the number was 73 countries/territories.
64 countries reported established population of vector mosquito, with no infections documented.
13 countries recognised human-to-human transmission of Zika infection.
→ In October-2016 the number was 12 countries/territories.
31 countries/territories reported Zika infection related microcephaly and pathological disorders of the central nervous system.
→ In October-2016 the number was 22 countries/territories.
23 countries/territories
indicated enhanced frequency of Guillain-Barré syndrome (GBS)
and/or Zika infection confirmed by laboratory tests in GBS
patients.
Zika virus specificities known so far(for historysee → 2016/Actuality) :
Initially, Zika infections concluded in sporadic and mild symptoms.
Initially, there was a slow spread of the virus (East-Africa → West-Africa ±
Asia), which later accelerated (Asia → Pacific region → Americas) extending also to areas endemic for other flavivirus like Dengue or West-Nile.
Following the first registered epidemic, the severity of infections varied with biogeographical locations (Thailand
<<< Brazil).
As for Zika's spread:
Vectors proven for transmitting Zika virus in nature (confirmed by detecting virus RNA in the vector): Aedes
(Ae.) africanus, Ae. furcifer, Ae. luteocephalus, Ae.
vittatus, Ae. dalzieli, Ae. hirsutus, Ae. metalicus, Ae. taylori, Ae.
aegypti, Ae. unilineatus, Anopheles coustani, Culex perfuscus, Mansonia
uniformis
Vectors proven for transmitting Zika virus in urbane environment(confirmed by detecting virus RNA in the vector):
Ae. aegypti (also vector for flavivirus Dengue) > Nigéria, Malaysia, Indonézia, Francia Polinézia
Ae. albopictus (also vector for alphavirus Chikungunya) > Gabon, Brazil
[Smartt Ch.T.et al. (+11)(2017):
Evidence of Zika Virus RNA Fragments in Aedes albopictus (Diptera:
Culicidae) Field-Collected Eggs From Camaçari, Bahia, Brazil J Med Entomol tjx058. doi: 10.1093/jme/tjx058]
Ae. hensilli (???) > Yap Island (multitude of insects with no detectable Zika RNA)
Ae. polynesiensis (???) > French Polynesia (multitude of insects with no detectable Zika RNA)
Further insects as vectors? What do we know about non-insect vectors?
Man-to-man transmission of Zika virus is disclosed.
a/ horizontal (sexual transmission ✔ via blood transfusion ✔ via other body fluids?)
b/vertical (from infected mother to fetus)
[Basu R., Tumban E. (2016): Zika
Virus on a Spreading Spree: what we now know that was unknown in the
1950’s Virol J. 13: 165. PMCID: PMC5053350]
Regarding serological
cross reactions between members of Flaviviridae family and, the
questioned sensitivity of Zika serological detection, the gold standard
in Zika (RNA) detection is the analysis of body fluids by laboratory RT-qPCR (Reverse Transcription Quantitative real time Polymerase Chain Reaction).
Besides RT-qPCR, a new trend in detecting virus infection isthe on site Point-of-Care
(POC) detection giving results within an hour, most preferably in
saliva samples, with no need for PCR platforms and performed in
portable and disposable microfluidic cassettes (reverse transcription +
izothermal nucleic acid amplification + colorimetric detection >
sensitivity = 5 PFU).Further option in on site POC detectionistheuse ofsmartphone applicationfor wireless actuation, for monitoring nucleic acid amplification, for analyses of results.
[Eboigbodin K. et al. (2016): Rapid molecular diagnostic test for Zika virus with low demands on sample preparation and instrumentation Diagnostic Microbiology and Infectious Disease 86: 369–371.] [Song J. et al. (2016): Instrument-Free Point-of-Care Molecular Detection of Zika Virus Anal Chem. 88: 7289–7294.] [Priye A. et al. (2017): A
smartphone-based diagnostic platform for rapid detection of Zika,
chikungunya, and dengue viruses Scientific Reports 7,
Article number: 44778
doi:10.1038/srep44778]
Lines of Zika virus evolved by genetic recombination are the Zika-Africa (East- and West-African clusters of genotypes)
and the Zika-Asia with more than 95% identitity in aminoacids of virus
envelope 'E' glycoproteins (target for neutralizing antibodies).
Difference
between the virus lines regarding kinetics of replication was
confirmed by dendritic cells in vitro infected with Zika lines (dendritic
cells of innate immune system = professional cells throughout the
body dedicated to antigen recognition and presentation, activating
among others virus eliminating CD8+ T cells) . As
of the observations, Zika-Africa concluded into more serious
infection due to its higher replication rate, ultimately leading to
induced cell death. It seems that evolutionary advantage is provided to
Zika-Asia by its lower replication kinetics with no induced cell
death in the infected cells. Upon in vitro virus infection only slight dendritic cell activation resulted; the inhibition of Type I Interferon (IFN1) translation helped virus replication evade dendritic cell surveillance. Still, signalling pathways of receptor family RLR (RIG-1-like receptors)
are left stimulatable bearing potential for further antiviral actions. [Bowen J.R., Quicke K.M., Maddur M.S., O’Neal J.T., McDonald C.E.,
Fedorova N.B., Puri V., Shabman R.S., Pulendran B., Suthar M.S. (2017):
Zika Virus Antagonizes Type I Interferon Responses during Infection of Human Dendritic Cells PLOS Pathogenshttps://doi.org/10.1371/journal.ppat.1006164] [Yueh-Ming Loo and Michael Gale, Jr. (2011): Immune signaling by RIG-I-like receptors Immunity 34: 680–692.]
The
biogeographical sequence in appearance of the virus is: East-Africa
> West-Africa > Asia > Pacific region > Americas, the latter with the emergence of a new lineage Zika-America.
As
of results on genome sequencing and diversity studies (2017),
founder lineage Zika-America is a derivative of Zika-Asia line genotype. The genetic diversity in founder lineage Zika-America is far lower than that of Zika-Asia line (Zika-Asia >> Zika-America);
a difference in diversity expectedly reduce in near future as a
consequence of mutation evolution in company with virus spread on the American
continent.
The suggested source of propagation in the origin of lineage Zika-America is Northeast Brazil
and/or the Caribbean area with an estimated timing of January-February
2014, i.e. long before the outbreak of the epidemics. Hence, development in diagnostic tools and enhancing diagnostic sensitivity are of high emphases in progression of this field.
[Matranga C.B. et al. (+26)(2014): Enhanced methods
for unbiased deep sequencing of Lassa and Ebola RNA viruses from
clinical and biological samples Genome Biol. 15:
519. PMCID: PMC4262991]
[Quick J. et al. (+27)(2017): Multiplex PCR method
for MinION and Illumina sequencing of Zika and other virus genomes
directly from clinical samples Nature Protocols 12,
1261–1276 (2017) doi:10.1038/nprot.2017.066]
Epidemics of 2015-2016 inform us about Zika neurotropism, the detrimental effects on
embryonal neurogenesis and the neurodegenerative effects on mature nervous system (e.g. sensory
polyneuropathia). Zika neurotropism is already experimentally confirmed.
[Bayless N.L.
et al. (2016): Zika Virus Infection Induces Cranial Neural Crest Cells
to Produce Cytokines at Levels Detrimental for Neurogenesis
Cell Host & Microbe 20: 423-428.]
[Li
H. et al. (2016): Zika Virus Infects Neural
Progenitors in the Adult Mouse Brain and Alters
Proliferation
Cell Stem Cell 19: 593–598.]
[Nowakowski T.J. et al. (2016): Expression Analysis Highlights AXL as a Candidate
Zika Virus Entry Receptor in Neural Stem Cells Cell Stem Cell 18: 591-596.] [Chavali P.L. et al. (+15) (2017): Neurodevelopmental protein Musashi-1 interacts with the Zika genome and promotes viral replication Science 357: 83-88.] [Ling Yuan et al (+22) (2017): A single mutation in the prM protein of Zika virus contributes to fetal microcephaly Science
DOI: 10.1126/science.aam7120]
A
further step in experimental approaches is the establishment of a
murine model for detailed analysis of neurocognitive deficiencies
caused by members of the Flavivirus genus. The first series of
observations were collected byinfectionwithflavivirus West Nile Virus (WNV). →In mice with acute infection and also in mice after recovery, presynaptic loss i.e. degradation of presynapses with no harm to the axon could be detected.
In the hippocampus area of the brain in WNV-infected mice, presynaptic degradation
was mediated by the presence of complement cascade initiator C1qa +
complement C3 + microglia cells with cell surface C3aR receptors
recognizing complement C3 degraded products + microglial
phagocytosis machinery (cellular compartments, enzymes, coding genes). An important message from the observation above: loss of presynapses could also be observed in hippocampus of infected animal lacking mature B lymphocytes.
This finding highlights complement functions separate from
mature B cell effector mechanisms, in flavivirus infected
organism.
[Vasek M.J. et al. (+21)(2016): A complement–microglial axis drives synapse loss
during virus-induced memory impairment Nature 534: 538-543. LETTER doi:10.1038/nature18283]
Questions raised
1. Main and auxiliary reasons of Zika vírus
spread,
biogeographical variations,
infection with increased severity of syndromes along with in later epidemics,
from the biological,
physical, meteorological,
geological, social point of view? Some points have already been
discussed (for details→ 2016/Actuality).
In
broader sense: which of biological, epidemiological, socioeconomical considerations (population size, variations in geno- and phenotypes, population age pyramid, norms and motivations in society, traditions ...) and which of mathematical models (statistical, machine-learning, compartmental-SIR, -SIS, -MSIR, -SEIR, MSEIR, -SEIS, -MSEIS ...) provide help sufficient for forecasting and managing the cyclic
emergence-retreat-reappearance of epidemics associated with transmission of infective agents within and inter populations, like in case
of Zika virus?
2. Observations on other members of the Flavivirus
genus (Dengue virus/DENV, West Nile virus/WNV, yellow fever virus/YFV,
Japanese encephalitis virus/JEV, tick-borne encephalitis virus/TBE)
if adaptable in Zika
virus research?
3. Host immune history and status, preceding Flavivirus infection (DENV, WNV...)
with poor or non-neutralizing antibodies left behind, their aggravating
impact on the outcome of the antigenically close Zika
infection: chances for ADE (Antibody-Dependent Enhancement) and for OAS (original Antigenic sin)?
Related Experimental Approach
Anti-DENV human monoclonal antibody + Zika virusadministered toin vitromyeloid U937 cell line ⇒ determination of virus titer in culture supernatant, FACS analysis of infected culture cells ⇒ in result,observation of Zika-ADE in vitro.
[Dejnirattisai W. et al.(2016): Dengue virus sero-cross-reactivity drives antibody-dependent enhancement of infection with zika virus Nat. Immunol. 17: 1102-1108.]
Note
anti-DENV antibodies provoking Zika-ADE are poor neutralizing antibodies.
the timing of Zika infection following DENV
infection is crucial since protection against or enhancement of disease by crossreacting antibodies
can change with time.
Related Experimental Approach Anti-DENV human plasma OR anti-WNV human plasma OR purified plasma IgG administered to in vitromyeloid K562 cell line then infected with Zika virus ⇒ in result, observation of Zika-ADE in vitro.
AND
Anti-DENV human plasma OR anti-WNV human plasmaOR purified plasma IgG injected into mice then infected with Zika virus ⇒ in result, observation of Zika-ADE in vivo.
[Bardina S.V. et al.(2017): Enhancement of Zika virus pathogenesis by preexisting antiflavivirus immunity Science 356: 175-180.]
Note
ADE
was observed at low concentrations of immune plasma and low titers of
antibodies. ADE was accompanied by fever (≥ 38 oC) and intense viremia in the testes and
the spinal cord.
Compared to anti-DENV antibodies, anti-WNV antibodies were less potent in Zika disease enhancement.
Preceding flavivirus (DENV/WNV/...) historyfollowed by Zika infection: chance for OAS?
[Mee Sook Park et al.(2016): Original Antigenic Sin Response to RNA Viruses and Antiviral Immunity Immune Netw. 16: 261-270.]
The
immunbiological basis of the phenomenon is the rapid multiplication of
viruses and the accompanying diverse antigenicity.
Interpretation of the phenomenon: ability of the first antigen variant to determine - imprint - immune response.
Originally, the
phenomenon - immunological imprinting - was observed in influenza virus
infection, when the first encounter of the host with a specific virus
strain harboring characteristic antigen(s) - variant Ag1 - determined
the production of antibodies specific to variant Ag1 even
when reinfection happened with the same strain though harboring
different antigen(s) - variant Ag2 -.
Preceding non-Flavivirus infection, does it have an impact on the outcome of Zika infection?
4. Development of Zika-selective serodiagnostics OR sero-genodiagnostics?
Detection of Zika infection
- diagnostic windows according to present day knowledge -
Serum sample: few days before and after onset of symptoms. Whole blood sample: viremia within 2 months following onset of symptoms (left for confirmation). IgM antibody titer: from 4-7 days to appr. 12 weeks after onset of symptoms. Neutralizing antibodies: persistence even for years. Urine sample: higher than in serum virus titer, 7-14 (or more?) days after onset of symptoms. Saliva sample: higher than in serum virus titer, diagnostic window comparable to that of urine EXCEPT inconsistency of saliva samples.
5. Preventing epidemics AND support to embryogenesisbynew concepts invaccine design?
To answer questions 2-3-4-5, the structural and functional characteristics of Zika virus are to be explored.
In 2016 Sirohi et al. published their comparative cryo-electronmicroscopic observations on Zika virus [for details → 2016/Actuality]. The study was further extended in 2017 by Prasad V.M. et al. publishing cryo-electronmicroscopic features of immature virions (line Zika-Asia > strain H/PF/2013
+ mosquito C6/36 cells in vitro →incubation16h under 30oC→stop maturation by NH4Cl→ immature virions ready for studies).
[Vidya
Mangala Prasad, Andrew S Miller, Thomas Klose, Devika Sirohi, Geeta
Buda, Wen Jiang, Richard J Kuhn & Michael G Rossmann
(2017): Structure of the immature Zika virus at 9 Ĺ resolution
Nature
Structural & Molecular Biology doi:10.1038/nsmb.3352
Published online 09 January 2017 ]
The cryo-electronmicroscopic studies have disclosed distinctive features between mature and immature Zika virions hence, the virus map obtained by the observations has later led to diverse solutions in vaccine development.
1. Features of the mature Zika virion
Expression of virus surface 'E' (envelope) protein dimers;among them'M' (membrane) proteins have hidden conformation
('E' and 'M' are transmembrane proteins).
'E'
protein/glycoprotein domains and functions (DI-DII-DIII):
* adhesion of virus to target cells, docking on cell surface receptors (DIII); * dimerization (DII); * virus surface+target cell
membrane fusion (DII distal hydrophobic, conserved loop); * DII domain regions flexibly held-together; * DI domain interposed between DII domain regions.
'E'
glycoprotein: main target of neutralizing antibodies.
2. Features of the immature
Zika virion
In its intracellular phase of lifecycle, Zika virus particles
having assembled in the endoplasmic reticulum of the infected cell move
towards the trans-Golgi network (TGN) where the low pH and the
proteolytic enzymes provide conditions for further steps in virus
maturation (> cleavage of immature virions' polyproteins by furin type enzyme proprotein
convertase/serine protease > separation of structural from nonstructural proteins, a process similar to that of Dengue vírus, of Ebola virus, of HIV, of Influenza vírus, under maturation).
Virus surface trimers composed of 'E'
(envelope) glycoprotein and 'prM' (precursor
membrane) protein.
'E'
glycoprotein domain DII: distal hydrophobic conserved loop is hidden (inactive) by 'pr'
domain of 'prM'
protein (>
'prM' acting here as chaperon to assist 'E' structural formation).
Flavivirus
under proteolytic maturation: following cleavage of soluble 'pr' domains from 'prM' proteins, mature virions leave the cell.
[Stadler, K., Allison, S.L., Schalich, J. & Heinz, F.X. (1997): Proteolytic
activation of tick-borne encephalitis virus by furin. J. Virol. 71: 8475–8481.] [Yu, I.-M. et al (2008):. Structure of the immature dengue virus at low pH primes proteolytic maturation. Science 319: 1834–1837.]
Cleavage of 'pr'
domain from 'prM' protein can be performed completely, partially, or in fact, can be missing ⇒viruses released from the infected cell are heterogeneous populations of mature, partially mature and immature virions.
[Poonsook Keelapang et al.(2004):
Alterations of pr-M Cleavage and
Virus Export in pr-M Junction Chimeric Dengue Viruses J
Virol. 78: 2367–2381.]
[Theodore C.
Pierson and Michael S. Diamond (2012): Degrees of maturity: The complex structure and
biology of
flaviviruses Curr Opin Virol. 2: 168–175.]
Virus surface trimers kept together by stable conformational interactions ⇒ virus surface trimer todimer rearrangement is slow and cumbersome along with maturation.
Unique to Zika virus: capsid protein like densities found on the inner surface of virus membrane
> a feature missing in mature virions. Manifestation of
genome protection whilst virus maturation?
In
effect, features detailed above provide basis for the emergence of
heterogeneous virus populations rich in immature forms released
from the infected cells, a process ending up in:
⇒ heterogeneity of virus coatantigens ⇒ conformational hindrance of, or, completely missing mature virus surface consensus antigens⇒ partial cleavage of'prM' protein giving access to immature surface epitopes ⇒ high amount of neutralizing antibodies produced against more diverse epitopes ⇒besides
traditional solutions in vaccination (e.g. immunization
with inactivated virus) new concepts are put into practice.
One of the new concepts is shown in the elucidative studies of Pardi et al. (2017): [Pardi N. et al. (+36)(2017): Zika virus protection by a single low-dose nucleoside-modified mRNA vaccinationNature 543: 248–251.]
The research group accomplished immunization with mRNA coexpressing Zika 'prM-E' glycoproteins (French Polynesia strain H/PF 2013). The vaccine candidate mRNA contains a modified nucleoside (1-methyl-pseudouridine/m1Ψ).
The presence of modified nucleoside m1Ψ in mRNA give rise to enhancement intranslation, decrease in mRNA immunogenicity, and increase in mRNA stability.
[Andriesa
O. et
al.(2015): N1-methylpseudouridine-incorporated mRNA outperforms
pseudouridine-incorporated mRNA by providing enhanced protein
expression and reduced immunogenicity in mammalian cell lines and mice
Journal of Controlled Release 217: 337–344.]
Some points in the technique:
*formulation of vaccine candidate mRNA in lipid nanoparticles.
Preclinical observationswithvaccine candidate mRNA - experiments in Rodents
In C57BL/6 mice (receiving 1x30 µg in intradermal injection) the level of serum IgG specific for 'E' protein reached its maximum 8
weeks after immunization and was kept by weeks 8-20.
Features of anti-Zika virus neutralizing antibodies (nAB)
A/ The plaque reduction neutralization test50 (= PRNT50 nAB assay) showed peak titer by week 16 after immunization, the same was observed until week 20.
B/
Zika virus reporter particle assay (RVP nAB assay) titers were at maximum by week 8 after immunization, and reduced to less than a half by week 20.
C/ Upon infection with heterologous Zika strain (Puerto Rico 2015 strain PRVABC59 /intravenousinjection of 200 PFU) on week 2 and 20 after immunization:
* following
infection on week 2 after immunization, in 8 of 9 control animals
viremia was detected on third day (median 14.000 copies of virus
RNA/ml blood).
No viremia was detected in 9 of 9 animals immunized with Zika 'prM-E' mRNA.
* following
infection on week 20 after immunization, in 5 of 5 control
animals viremia was detected on third day (median 1200 copies of virus RNA/ml blood).
On day 3 and 7 after infection, no viremia was detected in 10 of 10 animals immunized with Zika 'prM-E' mRNA.
Preclinical observationswithvaccine candidate mRNA - experiments in Primates
In non-human primate Macaca Mulatta (Rhesus) monkeys (intradermal 1x600µg or 1x200µg or 1x50µg injection) given
either dose, the level of serum IgG specific for 'E' protein reached its
maximum by week 4 after immunization, and reduced to
approximately one-third up to week 12.
Features of anti-Zika virus neutralizing antibodies (nAB)
A/ The focus reduction neutralization test (FRNT) showed stable titers by weeks 2-12 after immunization.
B/ Zika virus reporter particle assay (RVP nAB assay) titers increased by more than one and a half fold from week 2 to week 4 after immunization.
C/ In neutralizing antibody assays, lines Zika-Africa and Zika-Asia represented a single serotype, confirming preceding basic observation referred below.
Basic observation on Single Zika Serotype → Dowd
K.A. et al. (+13)(2016): Broadly Neutralizing Activity of Zika
Virus-Immune Sera Identifies a Single Viral Serotype Cell Reports 16: 1485–1491.
Expectedly, single Zika serotype makes possible the preventive or therapeutic administration of robust and effective antibody enough for
the neutralization of heterologous virus strains. Since the synthesis
and reactivity of neutralizing antibody in the
experiments did not show the feature of dose-dependence, the application of the lowest dose (here: 1x50µg >
cca 0.02 mg/ kg) in non-human primates seemed to be reasonable.
D/ Upon infection with heterologous Zika strain (Puerto Rico 2015 strain PRVABC59 /subcutan injection)on week 5 after immunization:
* in 6 of 6 control monkeys viremia was detected on third day (median 7000 copies virus RNA /ml blood).
* in 4 of 5 monkeys immunized with Zika 'prM-E' mRNA (50µg to 3 animals, 200µg to one animal), viremia was not detectable on days 3, 5, 7 post infection (< 50 copies virus RNA/ml blood).In the animalimmunized with the highest dose(600µg), slight viremia was detected on day 3 post infection (100 copies virus RNA/ml blood). The result claims for further experiments with larger number of animals involved.
Accordingto Pardi et al. (2017) studies,single low dose intradermal immunization with Zika 'prM-E'mRNA result in protection of mice and monkeys as well. As of the observations, Zika 'prM-E'mRNA vaccine candidate induces robust neutralizing antibody response.
Other Zika vaccine candidates: Larocca R.A. et al. (2016) and Abbink P. et al. (2016) preclinical studies on plasmid DNA vaccine and on inactivated Zika virus vaccine (for the story see → 2016/Actuality).
Taken together: whether conventional or genetically engineered vaccines of the future, the essential requirements are the same:
Safe vaccine
Long-lasting (lifelong ...) protection
Thrifty large scale manufacturing
In
line with preclinical results, with regard to deficiencies of
present-day knowledge, Zika vaccine candidates are comparable as follows.
Purified Inactivated Virus Vaccine
chance for infection ???
method adaptable for the expression of any selected protein/antigen (not applicable)
coexpression of multiple selected antigens
(not applicable)
thrifty large scale manufacturing ✔
low dose two times administration result in protection ✔
chance for preceding flavivirus history to influence operation of vaccine✔
plasmid DNA VaccineCoding for Virus Surface Structural Proteins
chance for integration into the host genome ???
method adaptable for the expression of any selected protein/antigen ✔
coexpression of multiple selected antigens ✔
thrifty large scale manufacturing ???
low dose single/two times administration result in protection ✔
chance for preceding flavivirus history to influence operation of vaccine???
messenger RNA (mRNA) VaccineCoding for Virus SurfaceStructuralProteins
nucleotide sequence not integrating into the host genome ✔
method adaptable for the expression of any selected protein/antigen ✔
coexpression of multiple selected antigens ✔
thrifty large scale manufacturing ???
low dose single administration result in protection ✔
chance for preceding flavivirus history to influence operation of vaccine ???
Beyond B cell mediated immune responses...
What do we know about T cell mediated immune responses in Zika infection? - So far so few.
An analysis on Dengvaxia clinical studies was published in July 2017, authored by S.B. Halstead. (Dengvaxia
or CYD-TDV is a recombinant live
attenuated four-chimeric/tetravalent vaccine comprising of
flavivirus Dengue virus 1-4 structural genes inserted into carrier
yellow fever 17D vaccine non-structural genes). Halstead's
thought provoking publication gives emphasis on T cell mediated
immunity in the elaboration of immune protection against virus
infection. More specifically, it underlines T cell importance in durable protection against heterotypic
virus reinfection. Further accent is given to pitfalls in the
interpretation of preclinical studies.
As for Halstead's view, at preclinical testing of vaccine
constructs in study subject, the presence of vaccine induced neutralizing antibody is not sufficient to meet functional criteria. According to his point, for
grading vaccine's antiviral efficacy and durability in study subjects reinfected with virus only some
weeks after immunization, the presence of
anamnestic neutralizing antibody is not a proof of protection since
concentration of antibody reduces with time. Adapting Dengue lessons to those of Zika infection, Halstead stresses CD4+/CD8+ T cell reactions activated by viral non-structural proteins as attributes to durable and effective immune protection (lysis
of infected cells, synthesis of cytokine cocktail in support of durable
and effective B cell responses induced by live attenuated vaccine ...). [Scott B Halstead
(2017): Achieving safe, effective, and durable Zika virus vaccines:
lessons from dengue
http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(17)30362-6/fulltext]
In line with those above, at present, there are two options in protection against Zika virus.
Algorithm-1
Pillar in antiviral protection is the antibody specific for viral structural proteins to avoid virus enter into further organs, tissues.
(e.g. antibodies specific for Hepatitis A, Hepatitis B, Japanese encephalitis virus, Poliovirus -1,
- 2, - 3, Tick-borne encephalitis)
Zika example
* In mice immunized with plasmid DNA (coding for virus surface 'prM-Env' proteins),
removal of CD4+ and/or CD8+ T lymphocytes did not result significant
changes in efficient protection against Zika infection. [Larocca R.A. et al.(+24) (2016): Vaccine protection against Zika virus from BrazilNature 536: 474-478.]
Algorithm-2
Pillar in antiviral protection is the T cell population activated by viral non-structural proteins for supporting effective and durable B cell/antibody response.
(e.g. vaccines of Smallpox, Yellow fever, Measles, Mumps, Rubella, Varicella)
Zika example
* Considering the tendency in Zika spread (→establishing populations in DENV and WNV endemic regions) and the serological cross reactions between members of Flaviviridae family it is supposed, that DENV specific, cross reactive memory T cells recognize Zika virus in DENV endemic regions (example of 'heterologous immunity').
Question remains: CD4+ and CD8+ T cell mediated reactions in Zika infected individuals?
Back to Zika virus structural and functional characteristics...
A report providing clues for answering some of the questions formatted in a paragraph above, has been published recently. In their report, Annamalai A.S. et al. discuss glycosylation of Zika virus surface 'E' protein, more specific, glycosylation of 'E' protein motif VNDT in context with virus polymorphism influencing immunogenicity, target cell/tissue tropism.
Supporting evidence is the finding that 'E' protein motif VNDTcould be detected lately in virus isolates of big epidemics, but not in some isolates from Africa. Motif VNDT of virus surface 'E' protein dimers (seeabove:featuresof mature
virion) is situated close to the fusion loop and to the interface between dimers so as the N-glycosylation of motif VNDT, the extent of it have
impacts on spatial conformation and also on functions such
as virus replication, immunogenicity, transmission, or virulence.
Deletion of motif VNDT or, replacement of aminoacids within the motif, both, had no significant effects on virus replication either in vivo (in experimerntal animals) or in vitro (in cell cultures). Compared to wild type Zika virus, deletion/replacement virus mutants showed significant decrease in their pathogenicity observed mainly at targeting the central nervous system. [Annamalai
A.S. et al (+11) (2017): Zika Virus Encoding Non-Glycosylated Envelope
Protein is Attenuated and Defective in Neuroinvasion J. Virol. 91: e01348-17 doi:10.1128/JVI.01348-17]
Concluding question: glycan mutant Zika virus adhesion to or membrane fusion with brain microvascular endothelial cells further, choroid plexus epithelial cells, are modified, maybe failed?
Zika vaccine constructs in clinical trials
Purified inactivated Zika virus ........ conventional active immunization
1. Clinical Trial NCT02963909 / situation on 22-11-2017: active
A Phase 1, First-in-human, Double-blinded, Randomized,
Placebo-controlled Trial of a Zika Virus Purified Inactivated Vaccine
(ZPIV) With Alum Adjuvant in Healthy Flavivirus-naive and
Flavivirus-Primed Subjects Sponsor:
National Institute of Allergy and Infectious Diseases (NIAID)
Single center, randomized, double blind (study subjects and investigators),
placebo controlled three armed Phase 1 clinical trial to assess the results of purified inactivated Zika virus
vaccine (ZPIV) administered i.m. in two doses 28 days apart to subjects without flavivirus history (flavivírus naif + ZPIV) and to subjects with flavivirus history (flavivírus JEV + ZPIV / flavivírus YFV + ZPIV).
A subgroup selected from the study arms are given a third dose of
ZPIV. Primary
goal: safety and efficacy of ZPIV administered in two doses to subjects
above. Safety and efficacy of the third ZPIV dose.
2. Clinical Trial NCT03008122 / situation on 22-11-2017: recruiting
Phase
I, Randomized, Double-blinded, Placebo-Controlled Dose De-escalation
Study to Evaluate Safety and Immunogenicity of Alum Adjuvanted Zika
Virus Purified Inactivated Vaccine (ZPIV) in Adults in a Flavivirus
Endemic Area Sponsor:
National Institute of Allergy and Infectious Diseases (NIAID)
Single center, randomized, double blind (study subjects and investigators),
placebo controlled, dose de-escalating (two experimental doses) Phase 1 clinical trial to evaluate safety and efficacy of purifiedinactivated Zika virus vaccine (ZPIV) given i.m. in two administration schedule 28 days apart.
3. Clinical Trial NCT02952833 / situation on 22-11-2017: recruiting
ZIKA Vaccine in Naive Subjects
Sponsor:
National Institute of Allergy and Infectious Diseases (NIAID)
Single center, randomized, double blind (study subjects and investigators),
placebo controlled dose reducing (three experimental doses) Phase 1
clinical trial for the assessment of safety and efficacy ofpurifiedinactivated Zika virus vaccine (ZPIV) given in two i.m. administration 28 days apart, to individuals with no preceding flavivirus history.
Plasmid DNA vaccine coding for virus surface structural proteins 'prM-E' or 'M-E'
1. Clinical Trial NCT02809443 / situation on 22-11-2017: active
Study of GLS-5700 in Healthy Volunteers Sponsor + Cooperator: GeneOne Life Science, Inc. + Inovio Pharmaceuticals Multicenter, Phase 1 clinical trial for the follow-up of safety, tolerability, immunogenicity of GLS-5700vaccine in healthy individuals. GLS-5700: plasmid with DNA content coding for Zika virus prM (precursor membrane) and E (envelope) transmembrane proteins.
2. Clinical Trial NCT02887482 / situation on 22-11-2017: active
Study of GLS-5700 in Dengue Virus Seropositive Adults
Sponsor + Cooperator: GeneOne Life Science, Inc. + Inovio Pharmaceuticals Multicenter, randomized, double blind Phase 1 clinical trial for the follow-up of safety, tolerability, immunogenicity of GLS-5700vaccine in subjects seropositive for Dengue virus. GLS-5700: plasmid with DNA content coding for Zika virus prM (precursor membrane) and E (envelope) transmembrane proteins.
3. Clinical Trial NCT02840487 / situation on 22-11-2017: active
Safety and Immunogenicity of a Zika Virus DNA Vaccine, VRC-ZKADNA085-00-VP, in Healthy Adults Sponsor:National Institute of Allergy and Infectious Diseases (NIAID) Multicenter, randomized Phase 1/1b clinical trial for the follow-up of safety, tolerability and immunogenicity of Zika virus DNA vaccine (VRC-ZKADNA085-00-VP) administered in four i.m. dosing designs. Vaccine: circular DNA plasmid coding for Zika virus strain H/PF/2013 prM (precursor membrane) and E (envelope) transmembrane proteins.
4. Clinical Trial NCT02996461 / situation on 22-11-2017: active
VRC
320: A Phase I, Randomized Clinical Trial to Evaluate the Safety and
Immunogenicity of a Zika Virus DNA Vaccine, VRC-ZKADNA090-00-VP,
Administered Via Needle and Syringe or Needle-free Injector, PharmaJet,
inHealthy Adults Sponsor: National Institute of Allergy and Infectious Diseases (NIAID)
Single center,
randomized Phase 1 clinical trial to study safety, tolerability, immunogenicity of Zika virus DNA vaccine (VRC-ZKADNA090-00-VP) administered i.m. in three dosing designs and manners. Vakcina: circular DNA plasmid coding for Zika virus strain H/PF/2013 prM (precursor membrane) and E (envelope) transmembrane proteins.
messenger RNA (mRNA) vaccine coding for virus surface structural proteins
1. Clinical TrialNCT03014089 / situation on 22-11-2017: recruiting
Safety, Tolerability, and Immunogenicity of mRNA-1325 in Healthy Adult Subjects
Sponsor + Cooperator: Moderna Therapeutics + Biomedical Advanced Research and Development Authority
Multicenter,
randomized, placebo controlled, dose finding Phase 1/2 clinical trial
for the follow-up of safety, immunogenicity of Zika mRNA 1325
vaccine in healthy individuals of non-endemic Zika free regions.
Source: ClinicalTrials.gov
A critical summary of Zika vaccine development racing with time, is at reach here:
[Chris
Morrison(2016): DNA vaccines against Zika virus speed into clinical
trials Nature Reviews Drug Discovery 15: 521–522.]
An alternative in managing and preventing Zika infection
Anti-Zika Chemotherapy
[Pascoalino B.S. et al.(2016): Zika
antiviral chemotherapy: identification of drugs and promising starting
points for drug discovery from an FDA-approved library PMCID:
PMC5112578]
The novelty disclosed in this remarkable publication is the robust pharmacological testing of FDA-approved chemicals inZika virus (KX197192.1/Pernambuco-Brazil/2015) infected in vitro cells (human hepatoma cells=Huh7; Aedes albopictus cells=C636; HB-112 mouse hybridoma cells and the ascites produced) by HCS/High Content Screening, a method comprising pharmacological and imaging technics. An advantage
of the method covering 72h incubation of the virus with the cells in vitro, is the combined
observation and evaluation of viruses and chemicals in action with conventional morphological parameters included (→ viruscellular localization byindirect
immunofluorescence using anti-'E' monoclonal antibodies). For antiviral reference compound, recombinant IFNα2A (interferon) was introduced. Among
the 725 compounds screened, due to criteria of selectivity, low
toxicity and maximum antiviral effects, five compounds were
found appropriate for further studies. The chemically and pharmacologically distinct five compounds are: → Lovastatin
(lipid lowering substance) → 5-Fluorouracil (antineoplastic substance; irreversible inhibition of thymidylate
synthase) → 6-Azauridine (antineoplastic and anti-psoriasis substance, broad spectrum antimetabolite, inhibition of DNA virus/RNA
virus replication) → Palonosetron (5-HT3 antagonist, antiemetic drug) → Kitasamycin (macrolide antibiotic).
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Bamne
M.N., Ponder C.A., Wood J.A., Mansour H., Frank E., Kupfer D.J., Young
M.W., Nimgaonkar V.L.(2013): Application of an ex vivo cellular model
of circadian variation for bipolar disorder research: a proof of
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Crane B.R., Young M.W. (2014): Interactive features of proteins composing eukaryotic circadian clocks Annual Rev. Biochem. 83: 191-219.
Garaulet
D.L., Sun K., Li W., Wen J., Panzarino A.M., O'Neil J.L., Hiesinger
P.R., Young M.W., Lai E.C.(2016): miR-124 Regulates Diverse Aspects of
Rhythmic Behavior in DrosophilaJ Neurosci. 36: 3414-3421.
Vienne J., Spann R., Guo F., Rosbash M. (2016): Age-Related Reduction of Recovery Sleep and Arousal Threshold in Drosophila Sleep 39: 1613-1624. ...........................................................................................................
"... for its work to draw attention to the catastrophic
humanitarian consequences of any use of nuclear weapons .... for its
ground-breaking efforts to achieve a treaty-based prohibition of such
weapons".
-ICAN- International Campaign to Abolish Nuclear Weapons
Reference (more: www.nobelprize.org)
Australia - 2017 Global civil campaign -ICAN- against nuclear weapons is founded for calling attention to the catastrophic consequences of their use.
The aim of ICAN: treaty-based international ban on use of any nuclear weapons.
Economy
"...for his contributions to behavioural economics...".
Reference (more: www.nobelprize.org)
Scientific Background on the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 2017