Long-Term Viruria in Zika Virus-Infected Pregnant Women, Brazil, 2016

Metabolomic Analysis of Key Regulatory Metabolites in the Urine of Flavivirus-Infected Mice

Objective

Dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV) are several important flaviviruses, and infections caused by these flaviviruses remain worldwide health problems. Different flaviviruses exhibit different biological characteristics and pathogenicity. Metabolomics is an emerging research perspective to uncover and observe the pathogenesis of certain infections.

Methods

To improve the understanding of the specific metabolic changes that occur during infection with different flaviviruses, considering the principle of noninvasive sampling, this article describes our comprehensive analysis of metabolites in urine samples from the three kinds of flavivirus-infected mice using a liquid chromatography tandem mass spectrometry method to better understand their infection mechanisms.

Results

The urine of DENV-, JEV-, and ZIKV-infected mice had 68, 64, and 47 different differential metabolites, respectively, compared with the urine of control mice. Among the metabolic pathways designed by these metabolites, ABC transporters, arginine and proline metabolism, and regulation of lipolysis play an important role. Furthermore, we predicted and fitted potential relationships between metabolites and pathways.

Conclusions

These virus-specific altered metabolites may be associated with their unique biological properties and pathogenicity. The metabolomic analysis of urine is very important for the analysis of flavivirus infection.

Experience with a triplex arbovirus nucleic acid test (NAT) at a Canadian Public Health Laboratory

BACKGROUND

Dengue, chikungunya and zika infections occur in tropical and subtropical regions of the world. We describe the utilization of an in-house nucleic acid test (NAT) targeting all three viruses for febrile returning travelers in Alberta, Canada.

METHODS

NAT was performed until 40 days from symptom onset or exposure due to the prolonged duration of zika virus RNA detection. From Sept 1, 2017 to August 31, 2019, 2552 specimens from 1932 patients were tested.

RESULTS

Approximately 2% of patients tested were NAT positive for dengue virus (n = 42), chikungunya virus (n = 4), and zika virus (n = 1). The majority presented with fever, myalgia and rash. Regions with the most frequent travel included SouthEast Asia (68.5%), South America (25%) and the Caribbean (6.5%). Ct values were stronger (~ 1.5 logs) for patients within 1-3 days following onset of clinical symptoms than those presenting later. Nineteen patients had urine and plasma submitted; 5 were positive for both specimens and 2 were positive only for dengue virus in the urine. Also, Ct values were lower for plasma when compared to the corresponding urine. RNA was detected until 10 days and 5 days post-exposure in plasma and urine respectively for dengue virus.

CONCLUSIONS

Owing to dengue viremia detected beyond the conventional 7 days and low levels of circulating zika virus globally, a cutoff of 14 days from symptom onset to NAT is sufficient to diagnose acute cases. Inclusion of a zoonotic history form that collects appropriate clinical history results in improved test utilization.

Evaluation of eight commercial Zika virus IgM and IgG serology assays for diagnostics and research

Several commercial Zika virus (ZIKV) serology assays have been developed since the recognition of ZIKV outbreaks as a Public Health Emergency of International Concern in 2016. However, test interpretation for ZIKV serology can be challenging due to antibody cross-reactivity with other flaviviruses like dengue virus (DENV). Therefore, we sought to evaluate the performance of eight commercially available ZIKV IgM and IgG assays across three testing platforms, namely, immunochromatographic tests (ICT), ELISAs and immunofluorescence tests (IIFT). The test panel comprised of 278 samples, including acute and convalescent sera or plasma from ZIKV-confirmed, DENV-confirmed, non-ZIKV and non-DENV patients, and residual sera from healthy blood donors. The ZIKV IgM and IgG serology assays yielded higher test sensitivities of 23.5% - 97.1% among ZIKV convalescent samples as compared to 5.6% - 27.8% among ZIKV acute samples; the test specificities were 63.3% - 100% among acute and convalescent DENV, non-DENV samples. Among the ELISAs and IIFTs, the Diapro ZIKV IgM ELISA demonstrated high test sensitivity (96%) and specificity (80%) when tested on early convalescent samples, while the Euroimmun ZIKV IgG ELISA yielded the highest test specificity of 97% - 100% on samples from non-ZIKV patients and healthy blood donors. For rapid ICTs, the LumiQuick IgM rapid ICT yielded low test sensitivity, suggesting its limited utility. We showed that commercial ZIKV IgM and IgG serology assays have differing test performances, with some having moderate to high test sensitivities and specificities when used in a dengue endemic setting, although there were limitations in IgG serology.

Low vector competence in sylvatic mosquitoes limits Zika virus to initiate an enzootic cycle in South America

Zika virus (ZIKV) has spread in the Americas since 2015 and the potential establishment of a sylvatic transmission cycle in the continent has been hypothesized. We evaluated vector competence of five sylvatic Neotropical mosquito species to two ZIKV isolates. Distinct batches of Haemagogus leucoceleanus, Sabethes albiprivus, Sabethes identicus, Aedes terrens and Aedes scapularis females were respectively orally challenged and inoculated intrathoracically with ZIKV. Orally challenged mosquitoes were refractory or exhibited low infection rates. Viral dissemination was detected only in Hg. leucocelaenus, but with very low rates. Virus was not detected in saliva of any mosquito orally challenged with ZIKV, regardless of viral isolate and incubation time. When intrathoracically injected, ZIKV disseminated in high rates in Hg. leucocelaenus, Sa. identicus and Sa. albpiprivus, but low transmission was detected in these species; very low dissemination and no transmission was detected in Ae. terrens and Ae. scapularis. Together these results suggest that genetically determined tissue barriers, especially in the midgut, play a vital role in inhibiting ZIKV for transmission in the tested sylvatic mosquito species. Thus, an independent enzootic transmission cycle for ZIKV in South America is very unlikely.

Zika virus infection as a cause of congenital brain abnormalities and Guillain-Barré syndrome: A living systematic review

Background: The Zika virus (ZIKV) caused a large outbreak in the Americas leading to the declaration of a Public Health Emergency of International Concern in February 2016. A causal relation between infection and adverse congenital outcomes such as microcephaly was declared by the World Health Organization (WHO) informed by a systematic review structured according to a framework of ten dimensions of causality, based on the work of Bradford Hill. Subsequently, the evidence has continued to accumulate, which we incorporate in regular updates of the original work, rendering it a living systematic review.

Methods: We present an update of our living systematic review on the causal relation between ZIKV infection and adverse congenital outcomes and between ZIKV and GBS for four dimensions of causality: strength of association, dose-response, specificity, and consistency. We assess the evidence published between January 18, 2017 and July 1, 2019.

Results: We found that the strength of association between ZIKV infection and adverse outcomes from case-control studies differs according to whether exposure to ZIKV is assessed in the mother (OR 3.8, 95% CI: 1.7-8.7, I ²=19.8%) or the foetus/infant (OR 37.4, 95% CI: 11.0-127.1, I ²=0%). In cohort studies, the risk of congenital abnormalities was 3.5 times higher after ZIKV infection (95% CI: 0.9-13.5, I ²=0%). The strength of association between ZIKV infection and GBS was higher in studies that enrolled controls from hospital (OR: 55.8, 95% CI: 17.2-181.7, I ²=0%) than in studies that enrolled controls at random from the same community or household (OR: 2.0, 95% CI: 0.8-5.4, I ²=74.6%). In case-control studies, selection of controls from hospitals could have biased results.

Conclusions: The conclusions that ZIKV infection causes adverse congenital outcomes and GBS are reinforced with the evidence published between January 18, 2017 and July 1, 2019.

Simultaneous Coinfection of Macaques with Zika and Dengue Viruses Does not Enhance Acute Plasma Viremia but Leads to Activation of Monocyte Subsets and Biphasic Release of Pro-inflammatory Cytokines

The consequences of simultaneous infection with Zika (ZIKV) and Dengue (DENV) viruses are poorly understood. Here we show that rhesus macaques experimentally coinfected simultaneously with ZIKV and DENV-2 demonstrated ZIKV or DENV replication without an enhancement of either infection. Coinfection was accompanied by an increase in the proportions of CD14⁺CD16⁺ pro-inflammatory subsets of monocytes and release of pro-inflammatory cytokines in the plasma. Numerous cytokines such as I-TAC, Eotaxin, RANTES, MCP-1, IFNγ and MIG demonstrated a biphasic peak that coincided with the differences in kinetics of ZIKV and DENV replication suggesting that viral replication likely differentially modulated the release of these cytokines. Red blood cell indices significantly declined during acute infection suggesting transient anemia, and was accompanied by elevated levels of muscle, liver and renal injury markers. These findings have implications for understanding the pathogenesis of coinfection in ZIKV and DENV endemic regions, and is the 1^st report of an experimental coinfection using the rhesus macaque model for ZIKV and DENV infections.

Evidence of natural Zika virus infection in neotropical non-human primates in Brazil

In Africa, Old World Primates are involved in the maintenance of sylvatic circulation of ZIKV. However, in Brazil, the hosts for the sylvatic cycle remain unknown. We hypothesized that free-living NHPs might play a role in urban/periurban ZIKV dynamics, thus we undertook an NHP ZIKV investigation in two cities in Brazil. We identified ZIKV-positive NHPs and sequences obtained were phylogenetically related to the American lineage of ZIKV. Additionally, we inoculated four C. penicillata with ZIKV and our results demonstrated that marmosets had a sustained viremia. The natural and experimental infection of NHPs with ZIKV, support the hypothesis that NHPs may be a vertebrate host in the maintainance of ZIKV transmission/circulation in urban tropical settings. Further studies are needed to understand the role they may play in maintaining the urban cycle of the ZIKV and how they may be a conduit in establishing an enzootic transmission cycle in tropical Latin America.

Zika virus infection and implications for kidney disease

High-level and persistent viruria observed in patients infected by Zika virus (ZIKV) has been well documented. However, renal pathology in acutely infected, immunocompetent patients remains subclinical. Moreover, the long-term impact of ZIKV infection, replication, and persistence in the renal compartment of adults and infants as well as immunosuppressed patients and solid organ transplant (SOT) recipients is unknown. Mechanisms involving host and viral factors that limit or control ZIKV pathogenesis in the renal compartment are important yet unexplored. The observation that long-term viral shedding occurs in the renal compartment in the absence of clinical disease requires further investigation. In this review, I explore Zika virus-induced renal pathology in animal models, the dynamics of virus shedding in urine, virus replication in glomerular cells, ZIKV infection in human renal transplantation, and the potential impact of long-term persistent ZIKV infection in the renal compartment.

Sexual transmission of Zika virus enhances in utero transmission in a mouse model

Zika virus (ZIKV) is an emerging mosquito-borne virus that can cause ZIKV congenital syndrome when a pregnant woman is infected. Sexual transmission has also been described for ZIKV, though the relationship between sexual transmission and vertical transmission has not been investigated. Here, viral dissemination to the female reproductive tract and fetuses was assessed in immunodeficient (AG129) female mice that were exposed to ZIKV by subcutaneous (s.c.) inoculation, intravaginal (ivag.) inoculation, or sexual transmission from infected male AG129 mice. Pregnant females had significantly increased ZIKV dissemination to the female reproductive tract compared to non-pregnant females when exposed by s.c. or ivag. inoculation. Sexual transmission resulted in significantly greater morbidity and mortality in females and higher ZIKV titers in the female reproductive tract than s.c. or ivag. inoculation. Ovaries from females infected sexually contained ZIKV RNA within the ovarian follicles. Furthermore, ZIKV titers were significantly higher in fetuses from dams exposed sexually compared to fetuses from dams exposed by s.c. or ivag. inoculation. These results demonstrate that sexual transmission enhances dissemination of ZIKV to the female reproductive tract and developing fetuses in a mouse model.