Complete Genome Sequences of Zika Virus Strains Isolated from the Blood of Patients in Thailand in 2014 and the Philippines in 2012

Interepidemic xenosurveillance of Japanese encephalitis virus and Zika virus in Culex mosquitoes from Ubon Ratchathani province, Thailand

Background and Aim

Some Culex mosquitoes are competent vectors for Japanese encephalitis virus (JEV) and Zika virus (ZIKV), which cause public health problems worldwide, especially in South-east Asia. Xenosurveillance of Culex mosquitoes remains limited compared with other common mosquito-borne diseases. This study aimed to identify JEV and ZIKV in field-caught Culex mosquitoes collected from Ubon Ratchathani province.

Materials and Methods

We investigated the presence of JEV and ZIKV in Culex mosquitoes from two districts in Ubon Ratchathani province, Thailand, and examined their role in viral interepidemic circulation. Female Culex mosquitoes (5,587) were collected using a mechanical aspirator from indoors and outdoors. The consensus sequences of the E and NS1 genes of JEV and the E gene of ZIKV were identified using real-time reverse transcription-polymerase chain reaction.

Results

From 335 sample pools that contain a total of 5587 adult female Culex mosquitoes collected from Don Yung, Mueang district (4,406) and Phon Duan, Det Udom district (1,181), none of the collected mosquitoes tested positive for either JEV or ZIKV.

Conclusion

This study did not find JEV and ZIKV in Culex mosquitoes collected from the area of collection, which may be due to the low circulating amount of the virus in the vectors in the area, making it undetectable, or it may be because Culex mosquitoes are not suitable vector for the virus being tested. However, further xenosurveillance study of JEV and ZIKV in mosquito is suggested to prepare for the next outbreak.

Defining the impact of flavivirus envelope protein glycosylation site mutations on sensitivity to broadly neutralizing antibodies

Antibodies targeting an envelope dimer epitope (EDE) cross-neutralize Zika virus (ZIKV) and dengue virus (DENV) and have thus inspired an epitope-focused vaccine design. There are two EDE antibody subclasses (EDE1, EDE2) distinguished by their dependence on viral envelope protein N-linked glycosylation at position N153 (DENV) or N154 (ZIKV) for binding. Here, we determined how envelope glycosylation site mutations affect neutralization by EDE and other broadly neutralizing antibodies. Consistent with structural studies, mutations abolishing the N153/N154 glycosylation site increased DENV and ZIKV sensitivity to neutralization by EDE1 antibodies. Surprisingly, despite their location at predicted contact sites, these mutations also increased sensitivity to EDE2 antibodies. Moreover, despite preserving the glycosylation site motif (N-X-S/T), substituting the threonine at ZIKV envelope residue 156 with a serine resulted in loss of glycan occupancy accompanied with increased neutralization sensitivity to EDE antibodies. For DENV, the presence of a serine instead of a threonine at envelope residue 155 retained glycan occupancy, but nonetheless increased sensitivity to EDE antibodies, in some cases to a similar extent as mutation at N153, which abolishes glycosylation. Envelope glycosylation site mutations also increased ZIKV and DENV sensitivity to other non-EDE broadly neutralizing antibodies, but had limited effects on ZIKV- or DENV-specific antibodies. Thus, envelope protein glycosylation is context-dependent and modulates the potency of broadly neutralizing antibodies in a manner not predicted by existing structures. Manipulating envelope protein glycosylation could be a novel strategy for engineering vaccine antigens to elicit antibodies that broadly neutralize ZIKV and DENV.IMPORTANCEAntibodies that potently cross-neutralize Zika (ZIKV) and dengue (DENV) viruses are attractive to induce via vaccination to protect against these co-circulating flaviviruses. Structural studies have shown that viral envelope protein glycosylation is important for binding by one class of these so-called broadly neutralizing antibodies, but less is known about its effect on neutralization. Here, we investigated how envelope protein glycosylation site mutations impact the potency of broadly neutralizing antibodies against ZIKV and DENV. We found that glycan occupancy was not always predicted by an intact N-X-S/T sequence motif. Moreover, envelope protein glycosylation site mutations alter the potency of broadly neutralizing antibodies in a manner unexpected from their predicted binding mechanism as determined by existing structures. We therefore highlight the complex role and determinants of envelope protein glycosylation that should be considered in the design of vaccine antigens to elicit broadly neutralizing antibodies.

Genetic diversity and phylogenetic analyses of Asian lineage Zika virus whole genome sequences derived from Culex quinquefasciatus mosquitoes and urine of patients during the 2020 epidemic in Thailand

Zika virus (ZIKV), a mosquito-borne flavivirus, has been continually emerging and re-emerging since 2010, with sporadic cases reported annually in Thailand, peaking at over 1000 confirmed positive cases in 2016. Leveraging high-throughput sequencing technologies, specifically whole genome sequencing (WGS), has facilitated rapid pathogen genome sequencing. In this study, we used multiplex amplicon sequencing on the Illumina Miseq instrument to describe ZIKV WGS. Six ZIKV WGS were derived from three samples of field-caught Culex quinquefasciatus mosquitoes (two males and one female) and three urine samples collected from patients in three different provinces of Thailand. Additionally, successful isolation of a ZIKV isolate occurred from a female Cx. quinquefasciatus. The WGS analysis revealed a correlation between the 2020 outbreak and the acquisition of five amino acid changes in the Asian lineage ZIKV strains from Thailand (2006), Cambodia (2010 and 2019), and the Philippines (2012). These changes, including C-T106A, prM-V1A, E-V473M, NS1-A188V, and NS5-M872V, were identified in all seven WGS, previously linked to significantly higher mortality rates. Furthermore, phylogenetic analysis indicated that the seven ZIKV sequences belonged to the Asian lineage. Notably, the genomic region of the E gene showed the highest nucleotide diversity (0.7-1.3%). This data holds significance in informing the development of molecular tools that enhance our understanding of virus patterns and evolution. Moreover, it may identify targets for improved methods to prevent and control future ZIKV outbreaks.

The Zika virus: Lurking behind the COVID-19 pandemic?

What is known and objective

The sudden and extensive outbreak of coronavirus (SARS‐CoV‐2) has overshadowed another developing viral threat: the Zika flavivirus. Of particular concern is that pregnant women can pass Zika virus to the foetus, and there is a strong implication of an association between Zika virus infection and foetal microcephaly. Currently, there is no vaccine, and there is no cure.

Methods

Published literature and Internet sources were searched for information related to Zika virus, its transmission, its clinical presentation and sequalae, prevention and implications (practice and regulatory) for healthcare providers. The identified English sources were reviewed, assessed and synthesized. Emphasis was placed on providing an overview of the problem, and identification of unmet needs and future directions.

Results and discussion

Zika virus poses a major challenge for healthcare providers, particularly in areas unaccustomed to it, since it is transmitted to humans by the vector Aedes aegypti mosquito. The outbreak impacts every healthcare provider, because every provider is required to report cases of Zika infection to their state or local health agencies––whether the infection is confirmed or merely suspected. Since the virus has become a worldwide crisis, healthcare providers will need to work across national boundaries and medical disciplines in order to educate patients about Zika symptoms and the mosquito vector. Until further information is known, infected patients (male and female) are being advised to avoid conceiving a child.

What is new and Conclusion

Until a vaccine is developed or effective treatment for Zika virus is discovered, healthcare providers must be AVP (aware, vigilant and proactive) in order to lessen the spread and impact of the implicated devastating birth defects (microcephaly) and other neurological disorders (eg Guillain‐Barré Syndrome) of this infection. Unfortunately, many knowledge gaps exist. There is an urgent need for a reliable, inexpensive diagnostic test, an effective treatment and an approved and readily available vaccine.

Until a vaccine is developed or effective treatment for Zika virus is discovered, healthcare providers must be proactive to lessen its spread and impact of implicated birth defects (eg, microcephaly) and other neurological disorders (eg, Guillain‐Barré Syndrome). Unfortunately, knowledge gaps exist. There is urgent need for a reliable, inexpensive diagnostic test, effective treatment and readily available vaccine.

Can in utero Zika virus exposure be a risk factor for schizophrenia in the offspring?

Objectives: Schizophrenia is a severe psychiatric illness that has been purported to be causally related to in utero infection of neurotropic organisms. For obvious ethical reasons, this hypothesis has never been tested prospectively in humans. However, with the recent introduction of Zika virus into the New World offers the opportunity to test the hypothesis of infection in schizophrenia.Methods: This is a directed review examining the hypothesis. The literature relevant to Zika virus transmission in the New World, its biology and neurotropy is reviewed.Results: Zika virus has been associated with a wide variety of neural tube and neuroanatomical abnormalities. In its original range, Zika is only infrequently associated with congenital anomalies, but in the New World, where the majority of the population has not developed immunity, infections are associated with a wide range of neurologic abnormalities.Conclusions: The current outbreak of Zika virus in the Western Hemisphere, offers the opportunity to prospectively examine the congenital infection hypothesis of the pathogenesis of schizophrenia.

Was Zika introduced to Brazil by participants at the 2013 Beach Soccer World Cup held in Tahiti: A phylogeographical analysis

BACKGROUND

Zika virus (ZIKV) was initially responsible for a limited number of punctual epidemics throughout Africa and Asia. Recently, large epidemics occurred in French Polynesia, Brazil and Pan-America. These outbreaks were associated with severe outcomes such as Guillain-Barré Syndrome and microcephaly of in-utero infected newborns. Previous studies demonstrated that ZIKV was introduced in Brazil from French Polynesia but failed to identify a founding event.

METHOD

All publicly available ZIKV full-genome sequences (n = 182) were phylogenetically analyzed, using Bayesian method, to estimate the introduction date of ZIKV into Brazil.

RESULTS

Introduction date into Brazil was estimated between 8th of July 2013 and 4th of November 2013, encompassing the Beach Soccer World Cup held in French Polynesia, in September 2013, which gathered Brazilian athletes and supporters. We also observed that ZIKV sequences from travelers infected in South-East Asia or in Pacific islands were closely related to viruses identified prior to the French Polynesian epidemic, underlining an endemic circulation of ZIKV in those countries since 2007, at least.

CONCLUSION

This work provides a narrower estimation of ZIKV introduction into Brazil and illustrates the need for a better exploration of ZIKV circulation and endemicity in South-East Asia, while epidemiological and prevention efforts have been mainly focused on the Pan-American epidemic.

Zika Virus in Israeli Travelers: Emergence of Asia as a Major Source of Infection

Zika virus (ZIKV) had emerged as a global arboviral concern since late 2015. In this study, we describe the results of ZIKV testing in returning Israeli travelers from Zika-endemic countries. We conducted a nation-wide prospective observational study, including all ZIKV tests during January 2016-June 2017. Zika virus infection was defined as confirmed, if diagnosed by polymerase chain reaction (PCR) or serology confirmed by neutralization, and as possible if diagnosed by serology alone. During the study period, 1,188 travelers were tested: 66.7%, 30.5%, 1.6%, and 1.2% had returned from the Americas, Asia, Africa, and Oceania, respectively. Thirty persons were diagnosed with ZIKV. Most travelers tested were women of reproductive age; the gender ratio among infected travelers however was 1.0. During 2016, 19/20 (95%) ZIKV cases were acquired in the Americas; in 2017, however, 6/10 (60%) cases were acquired in Asia. Of 248 symptomatic travelers, 28 (11.3%) were diagnosed with ZIKV infection, whereas only 2/940 (0.2%) of asymptomatic travelers were diagnosed with ZIKV infection Odds ratio = 59.7 (95% confidence interval: 14.1-252.5, P < 0.0001). Our findings suggest that although women are more likely to be referred for ZIKV testing, gender does not affect the likelihood of ZIKV infection and that asymptomatic ZIKV infection appears to be rare in travelers. Furthermore, it appears that in 2017, Southeast Asia emerges as the leading source of travel-related ZIKV infection.

Glycosylated diphyllin as a broad-spectrum antiviral agent against Zika virus

Background

Flaviviruses such as Zika cause sporadic pandemic outbreaks worldwide. There is an urgent need for anti-Zika virus (ZIKV) drugs to prevent mother-to-child transmission of ZIKV, new infections in high-risk populations, and the infection of medical personnel in ZIKV-affected areas.

Methods

Here, we showed that the small molecule 6-deoxyglucose-diphyllin (DGP) exhibited anti-ZIKV activity both in vitro and in vivo. DGP potently blocked ZIKV infection across all human and monkey cell lines tested. DGP also displayed broad-spectrum antiviral activity against other flaviviruses. Remarkably, DGP prevented ZIKV-induced mortality in mice lacking the type I interferon receptor (Ifnar1^−/−). Cellular and virological experiments showed that DGP blocked ZIKV at a pre-fusion step or during fusion, which prevented the delivery of viral contents into the cytosol of the target cell. Mechanistic studies revealed that DGP prevented the acidification of endosomal/lysosomal compartments in target cells, thus inhibiting ZIKV fusion with cellular membranes and infection.

Findings

These investigations revealed that DGP inhibits ZIKV infection in vitro and in vivo.

Interpretation

The small molecule DGP has great potential for preclinical studies and the ability to inhibit ZIKV infection in humans.

Molecular Epidemiology and Genetic Diversity of Zika Virus from Field-Caught Mosquitoes in Various Regions of Thailand

Zika virus (ZIKV) infection is an emerging and re-emerging arbovirus disease that is transmitted to humans through the bite of infected mosquitoes. ZIKV infections were first described in Thailand in 1954 from the sera of indigenous residents and several travelers returning from Thailand in 2014. However, reported cases in Thailand have been increasing since 2015 and 2016, and epidemiological information about the vectors of ZIKV is unclear. We investigated the molecular epidemiology and genetic diversity of ZIKV from mosquitoes collected from different geographic regions experiencing ZIKV outbreaks in Thailand. Polymerase chain reaction was used to amplify the non-structural protein (NS5) gene of ZIKV, which was then sequenced. A total of 1026 mosquito samples (626 females, 367 males, and 33 larvae) were collected from active ZIKV patients’ houses. ZIKV was detected in 79 samples (7.7%), including Aedes aegypti (2.24% female, 1.27% male, and 0.19% larvae), Culex quinquefasciatus (1.85% female, 1.66% male, and 0.29% larvae), and Armigeres subalbatus (0.1% female and 0.1% male), whereas no ZIKV was detected in Aedes albopictus. Phylogenetic analysis of the 79 positive samples were classified into two clades: Those closely related to a previous report in Thailand, and those related to ZIKV found in the Americas. This is the first report of the detection of ZIKV in Ae. aegypti, Cx. quinquefasciatus, and Ar. subalbatus mosquitoes, and genetic variations of ZIKV in the mosquitoes collected from several geographic regions of Thailand were examined. Detection of ZIKV in male and larval mosquitoes suggests that vertical transmission of ZIKV occurred in these mosquito species. This study provides a more in-depth understanding of the patterns and epidemiologic data of ZIKV in Thailand; the data could be used for future development of more effective prevention and control strategies of ZIKV in Thailand.

Re-visiting the evolution, dispersal and epidemiology of Zika virus in Asia

Based on serological evidence and viral isolation, Zika virus (ZIKV) has circulated for many years relatively benignly in a sylvatic cycle in Africa and an urban cycle in South East Asia (SEA). With the recent availability of limited but novel Indian ZIKV sequences to add to the plethora of SEA sequences, we traced the phylogenetic history and spatio-temporal dispersal pattern of ZIKV in Asia prior to its explosive emergence in the Pacific region and the Americas. These analyses demonstrated that the introduction and dispersal of ZIKV on the Pacific islands were preceded by an extended period of relatively silent transmission in SEA, enabling the virus to expand geographically and evolve adaptively before its unanticipated introduction to immunologically naive populations on the Pacific islands and in the Americas. Our findings reveal new features of the evolution and dispersal of this intriguing virus and may benefit future disease control strategies.

Zika Virus Infection in Syrian Golden Hamsters and Strain 13 Guinea Pigs

To evaluate potential immunocompetent small animal models of Zika virus (ZIKV) infection, we inoculated Syrian golden hamsters (subcutaneously or intraperitoneally) and strain 13 guinea pigs (intraperitoneally) with Senegalese ZIKV strain ArD 41525 or Philippines ZIKV strain CPC-0740. We did not detect viremia in hamsters inoculated subcutaneously with either virus strain, although some hamsters developed virus neutralizing antibodies. However, we detected statistically significant higher viremias (P = 0.0285) and a higher median neutralization titer (P = 0.0163) in hamsters inoculated intraperitoneally with strain ArD 41525 compared with strain CPC-0740. Furthermore, some hamsters inoculated with strain ArD 41525 displayed mild signs of disease. By contrast, strain 13 guinea pigs inoculated intraperitoneally with either strain did not have detectable viremias and less than half developed virus neutralizing antibodies. Our results support the use of the Syrian golden hamster intraperitoneal model to explore phenotypic variation between ZIKV strains.

Higher Cytopathic Effects of a Zika Virus Brazilian Isolate from Bahia Compared to a Canadian-Imported Thai Strain

Zika virus (ZIKV) is an emerging pathogen from the Flaviviridae family. It represents a significant threat to global health due to its neurological and fetal pathogenesis (including microcephaly and congenital malformations), and its rapid dissemination across Latin America in recent years. The virus has spread from Africa to Asia, the Pacific islands and the Americas with limited knowledge about the pathogenesis associated with infection in recent years. Herein, we compared the ability of the Canadian-imported Thai strain PLCal_ZV and the Brazilian isolate HS-2015-BA-01 from Bahia to produce infectious ZIKV particles and cytopathic effects in a cell proliferation assay. We also compared the intracellular viral RNA accumulation of the two strains by quantitative RT-PCR (reverse transcription polymerase chain reaction) analyses. Our observations show that HS-2015-BA-01 is more cytopathic than PLCal_ZV in proliferation assays in Vero, Human Embryonic Kidney HEK 293T and neuroblastoma SH-SY5Y cells. Quantitative RT-PCR shows that the level of viral RNA is higher with HS-2015-BA-01 than with PLCal_ZV in two cell lines, but similar in a neuroblastoma cell line. The two strains have 13 amino acids polymorphisms and we analyzed their predicted protein secondary structure. The increased cytopathicity and RNA accumulation of the Brazilian ZIKV isolate compared to the Thai isolate could contribute to the increased pathogenicity observed during the Brazilian epidemic.

Countering Zika Virus: The USAMRIID Response

The United States Army Medical Research Institute of Infectious Diseases (USAMRIID) possesses an array of expertise in diverse capabilities for the characterization of emerging infectious diseases from the pathogen itself to human or animal infection models. The recent Zika virus (ZIKV) outbreak was a challenge and an opportunity to put these capabilities to work as a cohesive unit to quickly respond to a rapidly developing threat. Next-generation sequencing was used to characterize virus stocks and to understand the introduction and spread of ZIKV in the United States. High Content Imaging was used to establish a High Content Screening process to evaluate antiviral therapies. Functional genomics was used to identify critical host factors for ZIKV infection. An animal model using the temporal blockade of IFN-I in immunocompetent laboratory mice was investigated in conjunction with Positron Emission Tomography to study ZIKV. Correlative light and electron microscopy was used to examine ZIKV interaction with host cells in culture and infected animals. A quantitative mass spectrometry approach was used to examine the protein and metabolite type or concentration changes that occur during ZIKV infection in blood, cells, and tissues. Multiplex fluorescence in situ hybridization was used to confirm ZIKV replication in mouse and NHP tissues. The integrated rapid response approach developed at USAMRIID presented in this review was successfully applied and provides a new template pathway to follow if a new biological threat emerges. This streamlined approach will increase the likelihood that novel medical countermeasures could be rapidly developed, evaluated, and translated into the clinic.

African and Asian Zika Virus Isolates Display Phenotypic Differences Both In Vitro and In Vivo

Zika virus (ZIKV) is a mosquito-borne member of the genus Flavivirus that has emerged since 2007 to cause outbreaks in Africa, Asia, Oceania, and most recently, in the Americas. Here, we used an isolate history as well as genetic and phylogenetic analyses to characterize three low-passage isolates representing African (ArD 41525) and Asian (CPC-0740, SV0127-14) lineages to investigate the potential phenotypic differences in vitro and in vivo. The African isolate displayed a large plaque phenotype (∼3-4 mm) on Vero and HEK-293 cells, whereas the Asian isolates either exhibited a small plaque phenotype (∼1-2 mm) or did not produce any plaques. In multistep replication kinetics in nine different vertebrate and insect cell lines, the African isolate consistently displayed faster replication kinetics and yielded ∼10- to 10,000-fold higher peak virus titers (infectious or RNA copies) compared with the Asian isolates. Oral exposure of Aedes aegypti mosquitoes with the African isolate yielded higher infection and dissemination rates compared with the Asian isolates. Infection of Ifnar1^-/- mice with the African isolate produced a uniformly fatal disease, whereas infection with the Asian isolates produced either a delay in time-to-death or a significantly lower mortality rate. Last, the African isolate was > 10,000-fold more virulent than the Asian isolates in an interferon type I antibody blockade mouse model. These data demonstrate substantial phenotypic differences between low-passage African and Asian isolates both in vitro and in vivo and warrant further investigation. They also highlight the need for basic characterization of ZIKV isolates, as the utilization of the uncharacterized isolates could have consequences for animal model and therapeutic/vaccine development.

Whole-genome sequence analysis of Zika virus, amplified from urine of traveler from the Philippines

Zika virus (ZIKV) (genus Flavivirus, family Flaviviridae) is an emerging pathogen associated with microcephaly and Guillain-Barré syndrome. The rapid spread of ZIKV disease in over 60 countries and the large numbers of travel-associated cases have caused worldwide concern. Thus, intensified surveillance of cases among immigrants and tourists from ZIKV-endemic areas is important for disease control and prevention. In this study, using Next Generation Sequencing, we reported the first whole-genome sequence of ZIKV strain AFMC-U, amplified from the urine of a traveler returning to Korea from the Philippines. Phylogenetic analysis showed geographic-specific clustering. Our results underscore the importance of examining urine in the diagnosis of ZIKV infection.

Chikungunya and Zika Virus Cases Detected against a Backdrop of Endemic Dengue Transmission in Vietnam

Between 2010 and 2014, four chikungunya and two Zika virus infections were identified among 8,105 febrile children in southern Vietnam. Zika viruses were linked to French Polynesian strains, chikungunya to Cambodian strains. Against a backdrop of endemic dengue transmission, chikungunya and Zika present an additional arboviral disease burden in Vietnam.

Clinical and biological insights from viral genome sequencing

Whole-genome sequencing (WGS) of pathogens is becoming increasingly important not only for basic research but also for clinical science and practice. In virology, WGS is important for the development of novel treatments and vaccines, and for increasing the power of molecular epidemiology and evolutionary genomics. In this Opinion article, we suggest that WGS of viruses in a clinical setting will become increasingly important for patient care. We give an overview of different WGS methods that are used in virology and summarize their advantages and disadvantages. Although there are only partially addressed technical, financial and ethical issues in regard to the clinical application of viral WGS, this technique provides important insights into virus transmission, evolution and pathogenesis.

Zika virus: An emerging flavivirus

Zika virus (ZIKV) is a previously little-known flavivirus closely related to Japanese encephalitis, West Nile, dengue, and yellow fever viruses, all of which are primarily transmitted by blood-sucking mosquitoes. Since its discovery in Uganda in 1947, ZIKV has continued to expand its geographic range, from equatorial Africa and Asia to the Pacific Islands, then further afield to South and Central America and the Caribbean. Currently, ZIKV is actively circulating not only in much of Latin America and its neighbors but also in parts of the Pacific Islands and Southeast Asia. Although ZIKV infection generally causes only mild symptoms in some infected individuals, it is associated with a range of neuroimmunological disorders, including Guillain-Barré syndrome, meningoencephalitis, and myelitis. Recently, maternal ZIKV infection during pregnancy has been linked to neonatal malformations, resulting in various degrees of congenital abnormalities, microcephaly, and even abortion. Despite its emergence as an important public health problem, however, little is known about ZIKV biology, and neither vaccine nor drug is available to control ZIKV infection. This article provides a brief introduction to ZIKV with a major emphasis on its molecular virology, in order to help facilitate the development of diagnostics, therapeutics, and vaccines.

Dengue and Zika viruses: lessons learned from the similarities between these Aedes mosquito-vectored arboviruses

The currently spreading arbovirus epidemic is having a severe impact on human health worldwide. The two most common flaviviruses, dengue virus (DENV) and Zika virus (ZIKV), are transmitted through the same viral vector, Aedes spp. mosquitoes. Since the discovery of DENV in 1943, this virus has been reported to cause around 390 million human infections per year, approximately 500,000 of which require hospitalization and over 20,000 of which are lethal. The present DENV epidemic is primarily concentrated in Southeast Asia. ZIKV, which was discovered in 1952, is another important arthropod-borne flavivirus. The neurotropic role of ZIKV has been reported in infected newborns with microcephaly and in adults with Guillain-Barre syndrome. Despite DENV and ZIKV sharing the same viral vector, their complex pathogenic natures are poorly understood, and the infections they cause do not have specific treatments or effective vaccines. Therefore, this review will describe what is currently known about the clinical characteristics, pathogenesis mechanisms, and transmission of these two viruses. Better understanding of the interrelationships between DENV and ZIKV will provide a useful perspective for developing an effective strategy for controlling both viruses in the future.

Complete Genome Sequences of Three Historically Important, Spatiotemporally Distinct, and Genetically Divergent Strains of Zika Virus: MR-766, P6-740, and PRVABC-59

Here, we report the 10,807-nucleotide-long consensus RNA genome sequences of three spatiotemporally distinct and genetically divergent Zika virus strains, with the functionality of their genomic sequences substantiated by reverse genetics: MR-766 (African lineage, Uganda, 1947), P6-740 (Asian lineage, Malaysia, 1966), and PRVABC-59 (Asian lineage-derived American strain, Puerto Rico, 2015).

The current status of Zika virus in Southeast Asia

OBJECTIVES

Zika virus currently poses a global threat and is a major public health issue throughout Latin America and the Caribbean. However, Zika virus infections in humans have also been observed in other regions, including Southeast Asia, where arboviral diseases are very common. In this study, we summarize the current status of Zika virus in Southeast Asia. This review aims to provide an overview of the current situation and also to suggest ways of adequately managing the emergence of Zika virus in Southeast Asia.

METHODS

The literature searching for the reports on Zika virus in Southeast Asia was done using standard database PubMed and the re-analysis and summarization on the reports was done.

RESULTS

A limited number of reports have addressed Zika virus disease in Southeast Asia, but it is has been confirmed that a problem already exists. Individual case reports and outbreaks of Zika virus have been confirmed in Southeast Asia. Several reports have also described patients becoming infected after visiting Southeast Asia. In addition, the concurrent circulation of Zika virus with other arboviruses has been confirmed.

CONCLUSIONS

As a tropical region with a high prevalence of arboviral diseases, the emergence of Zika virus in Southeast Asia is a major concern. It is essential for local medical personnel to recognize this disease. Given the status of Southeast Asia as a globally important tourist destination, continuous updates on the status of Zika virus in Southeast Asia are required and should be incorporated into global health advisories regarding travel.

Zika Virus Infection and Development of a Murine Model

In view of the recent outbreak of Zika virus (ZIKV), there is an urgent need to investigate the pathogenesis of the symptoms associated with ZIKV infection. Since the first identification of the virus in 1947, the pathologies associated with ZIKV infection were thought to be limited with mild illness that presented fever, rashes, muscle aches, and weakness. However, ZIKV infection has been shown to cause Guillain-Barré Syndrome, and numerous cases of congenital microcephaly in children have been reported when pregnant females were exposed to the virus. The severity and the rate of spread of ZIKV in the last year has drawn alarming interest among researchers to investigate murine models to study viral pathogenesis and develop candidate vaccines. A recent study by Lazear and colleagues, in the May 2016 issue of cell host and microbe, is an effort to study the pathogenesis of contemporary and historical virus strains in various mouse models.