Zika Virus Genome Research Articles

Comprehensive Annotation of Mature Peptides and Genotypes for Zika Virus.

The rapid spread of Zika virus (ZIKV) has caused much concern in the global health community, due in part to a link to fetal microcephaly and other neurological illnesses. While an increasing amount of ZIKV genomic sequence data is being generated, an understanding of the virus molecular biology is still greatly lacking. A significant step towards establishing ZIKV proteomics would be the compilation of all proteins produced by the virus, and the resultant virus genotypes. Here we report for the first time such data, using new computational methods for the annotation of mature peptide proteins, genotypes, and recombination events for all ZIKV genomes. The data is made publicly available through the Virus Pathogen Resource at www.viprbrc.org.

A Computational Approach to Design Potential Antiviral RNA for 3’UTR Post Transcriptional Gene Silencing of Different Strains of Zika Virus

: Background: Zika virus is a flare-up mosquito-borne virus that manifests itself in sporadic human infections with Zika fever. It has a serious affect in pregnant women. Mother transmits Zika virus infection to her infant during the time of delivery which results in the birth of newborn with microcephaly and some neurological malformations. Molecular studies revealed that the 3’UTR of Zika virus genome plays a vital role in viral replication and pathogenicity. So, the 3’UTR can be a suitable target for the prevention of viral multiplications and degree of pathogenicity. The activity of the 3’ UTR of Zika virus genome can be controlled by blocking or down regulating its expression through RNAi technology. RNAi works by silencing or turning off target gene expression using siRNA. Hence there arises an urgent need to design potential siRNA against the target sequence of Zika virus genome to control its replication and pathogenicity. This study is aimed to predict potential siRNA based therapeutics that might be used for the treatment of Zika virus infection. Methods: Designing siRNA against the target region of different strains of Zika virus is difficult due to its genetic diversity. Therefore, the work is done on the basis of rational siRNA designing method by targeting the 3’UTR of Zika virus strains. The prediction of potential siRNA was done by using various computational tools as searching target sequences, multiple sequences alignment, secondary structure prediction, siRNA-Target sequence interaction prediction and finally the evaluation of effectiveness of predicted and depicted siRNA. Results: Out of sixty siRNA only four potential siRNA were predicted and depicted rationally for silencing 3’UTR of 37 different Zika virus genome used in the study through RNAi technology. Conclusion: The outcomes of this study are four potential siRNA molecules which might be used as a potential antiviral RNA based therapeutics to suppress the Zika virus mediated infection.Key words: Antiviral RNA, RNAi technology, siRNA, Zika virus, 3’ UTR region.

The Role of Secretory Autophagy in Zika Virus Transfer through the Placental Barrier.

Recent studies indicated that the Zika virus genome could be detected in the amniotic fluid and the fetal brain, which confirms that the virus can cross the placental barrier. Secretory autophagy or exosome pathways may participate in this virus transfer. Autophagy modulators regulate autophagosome formation or membrane fusion with lysosomal vesicles and therefore inhibit viral nucleocapsid releasing or virus transfer to the fetus hypothetically. However, some autophagy modulators may enhance virus replication. Autophagy inhibitors may arrest placental development; while exaggeration of autophagy in human placenta may be associated with the fetal growth restriction. Therefore, autophagy modulators should be used carefully due to their complex clinical effects. Alternatively, exosome-specific inhibitors might be also considered, although their safety of both maternal and fetal conditions must be carefully assessed before any advancement to human clinical trials.

Characterization of cytopathic factors through genome-wide analysis of the Zika viral proteins in fission yeast

The Zika virus (ZIKV) causes microcephaly and the Guillain-Barré syndrome. Little is known about how ZIKV causes these conditions or which ZIKV viral protein(s) is responsible for the associated ZIKV-induced cytopathic effects, including cell hypertrophy, growth restriction, cell-cycle dysregulation, and cell death. We used fission yeast for the rapid, global functional analysis of the ZIKV genome. All 14 proteins or small peptides were produced under an inducible promoter, and we measured the intracellular localization and the specific effects on ZIKV-associated cytopathic activities of each protein. The subcellular localization of each ZIKV protein was in overall agreement with its predicted protein structure. Five structural and two nonstructural ZIKV proteins showed various levels of cytopathic effects. The expression of these ZIKV proteins restricted cell proliferation, induced hypertrophy, or triggered cellular oxidative stress leading to cell death. The expression of premembrane protein (prM) resulted in cell-cycle G1 accumulation, whereas membrane-anchored capsid (anaC), membrane protein (M), envelope protein (E), and nonstructural protein 4A (NS4A) caused cell-cycle G2/M accumulation. A mechanistic study revealed that NS4A-induced cellular hypertrophy and growth restriction were mediated specifically through the target of rapamycin (TOR) cellular stress pathway involving Tor1 and type 2A phosphatase activator Tip41. These findings should provide a reference for future research on the prevention and treatment of ZIKV diseases.

Zika virus genome biology and molecular pathogenesis

Zika virus (ZIKV) is an emerging RNA virus in the widespread Flavivirus genus. Recently, ZIKV has rapidly spread around the world and has been implicated in human disease, including neurological disorders, triggering public and scientific attention. Understanding how ZIKV causes disease is the highest priority, yet little is known about this virus. Here we examine the currently published data from ZIKV studies to provide the latest understanding of ZIKV genome biology and molecular pathogenesis. The ZIKV genome evolved rapidly from the Flavivirus genus and diverged from the members of this genus, even within the dengue virus cluster to which ZIKV belongs. Genome variations and divergences also exist among ZIKV strains/isolates. These genome divergences might account for the uniqueness of Zika disease. ZIKV infection activates not only the antiviral immune response but also the pro-inflammatory responses associated with disease symptoms. Strikingly, ZIKV activates protein complexes that are functionally associated with disease process, such as glial cell activation and proliferation (for example, Toll-like receptors), apoptosis and cell death, and inflammation. The activation of these complexes may critically contribute to Zika disease. The novel insights into ZIKV genome divergence and disease mechanisms summarized in this review will help accelerate the development of anti-ZIKV strategies.Emerging Microbes & Infections (2017) 6, e13; doi:10.1038/emi.2016.141; published online 22 March 2017

Zika Virus: Mode of transmission, Outrageous Effects and Clinical Trials

Zika has become one of the most worldwide spreading dangerous infection over the past decade because of its perpetual spread, initially in Asia-Pacific region, followed by its expeditious entry into the Western world. Zika virus was initially discovered in rhesus monkey in the forest of Uganda. But due to Unique genetic recombination in the genome of Zika virus has made the Zika infection more dangerous than the last one. Zika virus can be transmitted through both vector and non-vector means such as mosquito and sexual transmission. Eighty percent patient with Zika virus showed asymptomatic symptoms on the initial stage of disease onset but later symptoms can become severe. Zika has become one of the most dangerous infections of the 21st century because of its association with microcephaly and Guillain-Barre syndrome. Due to the rapid spread of virus WHO declares Zika virus as public health emergency in the end of 2016. There are many methods of early Zika virus diagnosing but the most common method used all over the world is RNA NAT analysis.RT-PCR can also use for the early diagnoses of Zika virus. At this time, clinical trials in different countries are continuing for the development of successful vaccines against Zika until now the most effective vaccine developed against Zika is DNA vaccine due to its effective mechanism of action and high efficacy. Various antiviral drugs against Zika have also approved by FDA. In our review, we emphasize on every aspect of Zika virus from the genetic basis to its effective treatment strategies.

Reverse Genetics of Zika Virus.

We have established a reverse genetic system for Zika virus (ZIKV). Five shuttle plasmids were constructed and assembled into the full-length cDNA clone of ZIKV genome. To ensure the stability of the cDNA clone, we used a low copy vector (pACYC177) and a set of unique restriction enzyme sites on the ZIKV genome to assemble the full-length cDNA clone. A T7 promoter was engineered in front of the viral 5' UTR for in vitro transcription. A hepatitis delta virus ribozyme (HDVr) sequence was engineered following the viral 3' UTR for generation of the authentic 3' end of the RNA transcript.

Identification and genetic characterization of Zika virus isolated from an imported case in China

Zika virus (ZIKV) is a reemerging flavivirus that stroke Brazil in 2015 and appeared in China for the first time in 2016. Sequencing and genomic analysis are essential for Zika virus study. However, the complete genome length of Zika virus is still a disputable issue. In this study, we reported the complete genomic sequence of Zika virus strain ZKC2/2016 from an imported case in China, in February 2016. The virus was isolated and virus characteristics were identified by cytopathic effect, quantitative real time-PCR, immunofluorescence assay and electronic microscopy. Next generation sequencing (NGS) technique and 5′ and 3′ Rapid Amplification cDNA Ends (RACE) PCR were used to sequence the complete genome. The genome length of this newly obtained Zika virus strain is 10,807base pairs (bp). Genetic analysis showed that ZKC2/2016, along with other Chinese Zika virus strains in 2016, formed three clusters within Asian linage. Multiple sequence alignment and prediction of RNA secondary structure of untranslated regions (UTRs) of ZKC2/2016 and several other ZIKV strains indicated that the difference of ZIKV genome length mainly laid in UTRs. Besides, those genomes shorter than 10,790bp were probably incomplete due to lacking conserved secondary RNA structures in untranslated regions which were playing important roles in flavivirus replication. Our findings benefited the disease control of Zika fever in China and the study of Zika virus genome.

N6-Methyladenosine in Flaviviridae Viral RNA Genomes Regulates Infection.

SummaryThe RNA modification N6-methyladenosine (m6A) post-transcriptionally regulates RNA function. The cellular machinery that controls m6A includes methyltransferases and demethylases that add or remove this modification, as well as m6A-binding YTHDF proteins that promote the translation or degradation of m6A-modified mRNA. We demonstrate that m6A modulates infection by hepatitis C virus (HCV). Depletion of m6A methyltransferases or an m6A demethylase, respectively, increases or decreases infectious HCV particle production. During HCV infection, YTHDF proteins relocalize to lipid droplets, sites of viral assembly, and their depletion increases infectious viral particles. We further mapped m6A sites across the HCV genome and determined that inactivating m6A in one viral genomic region increases viral titer without affecting RNA replication. Additional mapping of m6A on the RNA genomes of other Flaviviridae, including dengue, Zika, yellow fever, and West Nile virus, identifies conserved regions modified by m6A. Altogether, this work identifies m6A as a conserved regulatory mark across Flaviviridae genomes.

Congenital Zika Virus Infection

Recent studies have reported an increase in the number of fetuses and neonates with microcephaly whose mothers were infected with the Zika virus (ZIKV) during pregnancy. To our knowledge, most reports to date have focused on select aspects of the maternal or fetal infection and fetal effects. To describe the prenatal evolution and perinatal outcomes of 11 neonates who had developmental abnormalities and neurological damage associated with ZIKV infection in Brazil. We observed 11 infants with congenital ZIKV infection from gestation to 6 months in the state of Paraíba, Brazil. Ten of 11 women included in this study presented with symptoms of ZIKV infection during the first half of pregnancy, and all 11 had laboratory evidence of the infection in several tissues by serology or polymerase chain reaction. Brain damage was confirmed through intrauterine ultrasonography and was complemented by magnetic resonance imaging. Histopathological analysis was performed on the placenta and brain tissue from infants who died. The ZIKV genome was investigated in several tissues and sequenced for further phylogenetic analysis. Description of the major lesions caused by ZIKV congenital infection. Of the 11 infants, 7 (63.6%) were female, and the median (SD) maternal age at delivery was 25 (6) years. Three of 11 neonates died, giving a perinatal mortality rate of 27.3%. The median (SD) cephalic perimeter at birth was 31 (3) cm, a value lower than the limit to consider a microcephaly case. In all patients, neurological impairments were identified, including microcephaly, a reduction in cerebral volume, ventriculomegaly, cerebellar hypoplasia, lissencephaly with hydrocephalus, and fetal akinesia deformation sequence (ie, arthrogryposis). Results of limited testing for other causes of microcephaly, such as genetic disorders and viral and bacterial infections, were negative, and the ZIKV genome was found in both maternal and neonatal tissues (eg, amniotic fluid, cord blood, placenta, and brain). Phylogenetic analyses showed an intrahost virus variation with some polymorphisms in envelope genes associated with different tissues. Combined findings from clinical, laboratory, imaging, and pathological examinations provided a more complete picture of the severe damage and developmental abnormalities caused by ZIKV infection than has been previously reported. The term congenital Zika syndrome is preferable to refer to these cases, as microcephaly is just one of the clinical signs of this congenital malformation disorder.

First detection of natural infection of Aedes aegypti with Zika virus in Brazil and throughout South America

Zika virus (ZIKV) has caused a major epidemic in Brazil and several other American countries. ZIKV is an arbovirus whose natural vectors during epidemics have been poorly determined. In this study, 1,683 mosquitoes collected in the vicinity of ZIKV suspected cases in Rio de Janeiro, Brazil, from June 2015 to May 2016 were screened for natural infection by using molecular methods. Three pools of Aedes aegypti were found with the ZIKV genome, one of which had only one male. This finding supports the occurrence of vertical and/or venereal transmission of ZIKV in Ae. aegypti in nature. None of the examined Ae. albopictus and Culex quinquefasciatus was positive. This is the first report of natural infection by ZIKV in mosquitoes in Brazil and other South American countries. So far, Ae. aegypti is the only confirmed vector of ZIKV during the ongoing Pan-American epidemics.

Distinct Zika Virus Lineage in Salvador, Bahia, Brazil.

Sequencing of isolates from patients in Bahia, Brazil, where most Zika virus cases in Brazil have been reported, resulted in 11 whole and partial Zika virus genomes. Phylogenetic analyses revealed a well-supported Bahia-specific Zika virus lineage, which indicates sustained Zika virus circulation in Salvador, Bahia’s capital city, since mid-2014.

A Possible Mechanism of Zika Virus Associated Microcephaly: Imperative Role of Retinoic Acid Response Element (RARE) Consensus Sequence Repeats in the Viral Genome.

Owing to the reports of microcephaly as a consistent outcome in the fetuses of pregnant women infected with ZIKV in Brazil, Zika virus (ZIKV)—microcephaly etiomechanistic relationship has recently been implicated. Researchers, however, are still struggling to establish an embryological basis for this interesting causal handcuff. The present study reveals robust evidence in favor of a plausible ZIKV-microcephaly cause-effect liaison. The rationale is based on: (1) sequence homology between ZIKV genome and the response element of an early neural tube developmental marker “retinoic acid” in human DNA and (2) comprehensive similarities between the details of brain defects in ZIKV-microcephaly and retinoic acid embryopathy. Retinoic acid is considered as the earliest factor for regulating anteroposterior axis of neural tube and positioning of structures in developing brain through retinoic acid response elements (RARE) consensus sequence (5′–AGGTCA–3′) in promoter regions of retinoic acid-dependent genes. We screened genomic sequences of already reported virulent ZIKV strains (including those linked to microcephaly) and other viruses available in National Institute of Health genetic sequence database (GenBank) for the RARE consensus repeats and obtained results strongly bolstering our hypothesis that ZIKV strains associated with microcephaly may act through precipitation of dysregulation in retinoic acid-dependent genes by introducing extra stretches of RARE consensus sequence repeats in the genome of developing brain cells. Additional support to our hypothesis comes from our findings that screening of other viruses for RARE consensus sequence repeats is positive only for those known to display neurotropism and cause fetal brain defects (for which maternal-fetal transmission during developing stage may be required). The numbers of RARE sequence repeats appeared to match with the virulence of screened positive viruses. Although, bioinformatic evidence and embryological features are in favor of our hypothesis, additional studies including animal models are warranted to validate our proposition. Such studies are likely to unfold ZIKV-microcephaly association and may help in devising methods to combat it.

De Novo Structural Modeling and Conserved Epitopes Prediction of Zika Virus Envelop Protein for Vaccine Development.

Zika virus (Zika V) is a positive single-stranded RNA virus that is transmitted by mosquito bites. Zika V Envelop protein is antigenic and is involved in fusion and entry of viral particles into the cell. Till date, there is no vaccine and antiviral drug available against Zika V. Thus, there is a need to develop a vaccine against Zika V. This study was designed for the prediction of B cell and T cell epitopes that can be helpful in diagnosis and vaccine designing against this emerging threat. For this purpose, several B cell and T cell epitopes were predicted that are conserved among Zika virus genomes taken from 12 different countries. Peptides QTLTPVGRL, in case of major histocompatibility complex (MHC) class I, and IRCIGVSNRDFV, in case of MHC class II, are highly antigenic among T cell epitopes. Molecular docking was performed to study the interactions of B cell epitopes with HLA-B7. However, these predicted epitopes could play a constructive role in designing of a vaccine against Zika V.

Characterizing the Zika Virus Genome - A Bioinformatics Study.

The recent epidemic of Zika virus infections in South and Latin America have raised serious concern on its ramifications for the population in the Americas and spread of the virus worldwide. The Zika virus disease is a relatively new phenomenon for which sufficient and comprehensive data and investigative reports have not been available to date. To carry out a bioinformatics study of the available Zika virus genomic sequences to characterize the virus. 2D graphical representation method is used for visual rendering and compute sequence parameters and descriptors of the African and Asian-American groups of the Zika viruses to characterize the sequences. We also used MEGA5.2 and other software to compute various biological properties of interest like phylogenetic relationships, transition-transversion ratios, amino acid usage, codon usage bias and hydropathy index of the Zika genomes and virions. The phylogenetic relationships show that the African and Asian-American Zika virus genomes are grouped in two clades. The 2D plots of typical genomes of these types also show dramatic differences indicating that the gene sequences at the 5'-end coding regions for the structural proteins are rather strongly conserved. Among other characteristics, the transition/transversion ratio matrices for the sequences in each of the two clades show that analogous to the dengue virus, the transition rates are about 10 to 15 times the transversion rates. These findings are important for computer-assisted approaches towards surveillance of emerging Zika virus strains as well as in the design of drugs and vaccines to combat the growth and spread of the Zika virus.

Genetic and biological characterization of Zika virus from human cases imported through Shenzhen Port

During February to March 2016, a total of 13 Zika virus (ZIKV) cases were imported into China by travelers. Infection with ZIKV in humans results in fever, rash and has been associated with microcephaly as well as Guillain-Barre syndrome. ZIKV is a mosquito-borne flavivirus and Aedes mosquitoes are the main transmission vector species. Since Aede s are prevalent throughout China, ZIKV has the potential to become widely disseminated if not properly controlled. The genetic and biological characteristics of ZIKV should be thoroughly studied in order to enact effective countermeasures. A novel ZIKV strain (SZ_SMGC-1) was successfully isolated from the sera of an imported case returning to China from Fiji and Samoa at the Shenzhen Port. The entire viral genome was sequenced and compared to whole ZIKV genomes downloaded from GenBank. Results showed that SZ_SMGC-1 possesses the highest nucleotide identity (99.9%) to ZIKV from Fiji and Samoa, and also has high nucleotide identity (99.0%–99.4%) to ZIKV from Venezuela. Additionally, ZIKV is know to have evolved into distinct Asian and African lineages, and our phylogenetic analyses showed that the ZIKVs isolated from all imported cases into China clustered into the Asian lineage. To study the biological characteristics of ZIKV, SZ_SMGC-1 was used to infect different cell lines including the mosquito- derived C6/36, monkey-derived Vero and hamster-derived BHK-21 cells. Infection with SZ_SMGC-1 in vitro resulted in considerable cytopathic effects (CPE) to mammalian cells and supported replication of the virus to high titers, but did not cause readily observable CPE in C6/36 cells despite virus replication to comparable titers with mammalian cell lines. Interestingly, two clones of Vero and BHK-21 cell lines were used in the present study, respectively, but ZIKV SZ_SMGC-1 replicated much quicker to high virus titers in one clone than the other. Furthermore, there are no effective vaccine or drug for ZIKV until now. The results of the genetic and biological characteristics and the sensitive cell lines form the basis for further investigation into the pathogenesis and development of an effective medical countermeasure against ZIKV.

ZIKV - CDB: A Collaborative Database to Guide Research Linking SncRNAs and ZIKA Virus Disease Symptoms.

BackgroundIn early 2015, a ZIKA Virus (ZIKV) infection outbreak was recognized in northeast Brazil, where concerns over its possible links with infant microcephaly have been discussed. Providing a causal link between ZIKV infection and birth defects is still a challenge. MicroRNAs (miRNAs) are small noncoding RNAs (sncRNAs) that regulate post-transcriptional gene expression by translational repression, and play important roles in viral pathogenesis and brain development. The potential for flavivirus-mediated miRNA signalling dysfunction in brain-tissue development provides a compelling hypothesis to test the perceived link between ZIKV and microcephaly.Methodology/Principal FindingsHere, we applied in silico analyses to provide novel insights to understand how Congenital ZIKA Syndrome symptoms may be related to an imbalance in miRNAs function. Moreover, following World Health Organization (WHO) recommendations, we have assembled a database to help target investigations of the possible relationship between ZIKV symptoms and miRNA-mediated human gene expression.Conclusions/SignificanceWe have computationally predicted both miRNAs encoded by ZIKV able to target genes in the human genome and cellular (human) miRNAs capable of interacting with ZIKV genomes. Our results represent a step forward in the ZIKV studies, providing new insights to support research in this field and identify potential targets for therapy.

Nucleotide composition of the Zika virus RNA genome and its codon usage.

BackgroundRNA viruses have genomes with a distinct nucleotide composition and codon usage. We present the global characteristics of the RNA genome of Zika virus (ZIKV), an emerging pathogen within the Flavivirus genus. ZIKV was first isolated in 1947 in Uganda, caused a widespread epidemic in South and Central America and the Caribbean in 2015 and has recently been associated with microcephaly in newborns.MethodsThe nearly 11 kb positive-stranded RNA genome of ZIKV was analyzed for its nucleotide composition, also in the context of the folded RNA molecule. Nucleotide trends were investigated along the genome length by skew analyses and we analyzed the codons used for translation of the ZIKV proteins.ResultsZIKV RNA has a biased nucleotide composition in being purine-rich and pyrimidine-poor. This preference for purines is a general characteristic of the mosquito-borne and tick-borne flaviviruses. The virus-specific nucleotide bias is further enriched in the unpaired, single-stranded regions of the structured ZIKV RNA genome, thus further imposing this ZIKV-specific signature. The codons used for translation of the ZIKV proteins is also unusual, but we show that it is the underlying bias in nucleotide composition of the viral RNA that largely dictates these codon preferences.ConclusionsThe ZIKV RNA genome has a biased nucleotide composition that dictates the codon usage of this flavivirus. We discuss the evolutionary scenarios and molecular mechanisms that may be responsible for these distinctive ZIKV RNA genome features.

Zika virus genomes from Brazil

Zika Virus Outbreak The Zika virus outbreak is a major cause for concern in Brazil, where it has been linked with increased reports of otherwise rare birth defects and neuropathology. In a phylogenetic analysis, Faria et al. infer a single introduction of Zika to the Americas and estimated the introduction date to be about May to December 2013—some 12 months earlier than the virus was reported. This timing correlates with major events in the Brazilian cultural calendar associated with increased traveler numbers from areas where Zika virus has been circulating. A correlation was also observed between incidences of microcephaly and week 17 of pregnancy. Science , this issue p. [345][1] [1]: /lookup/doi/10.1126/science.aaf5036

Zika virus in the Americas: Early epidemiological and genetic findings.

Brazil has experienced an unprecedented epidemic of Zika virus (ZIKV), with ~30,000 cases reported to date. ZIKV was first detected in Brazil in May 2015, and cases of microcephaly potentially associated with ZIKV infection were identified in November 2015. We performed next-generation sequencing to generate seven Brazilian ZIKV genomes sampled from four self-limited cases, one blood donor, one fatal adult case, and one newborn with microcephaly and congenital malformations. Results of phylogenetic and molecular clock analyses show a single introduction of ZIKV into the Americas, which we estimated to have occurred between May and December 2013, more than 12 months before the detection of ZIKV in Brazil. The estimated date of origin coincides with an increase in air passengers to Brazil from ZIKV-endemic areas, as well as with reported outbreaks in the Pacific Islands. ZIKV genomes from Brazil are phylogenetically interspersed with those from other South American and Caribbean countries. Mapping mutations onto existing structural models revealed the context of viral amino acid changes present in the outbreak lineage; however, no shared amino acid changes were found among the three currently available virus genomes from microcephaly cases. Municipality-level incidence data indicate that reports of suspected microcephaly in Brazil best correlate with ZIKV incidence around week 17 of pregnancy, although this correlation does not demonstrate causation. Our genetic description and analysis of ZIKV isolates in Brazil provide a baseline for future studies of the evolution and molecular epidemiology of this emerging virus in the Americas.