Characterization of Lethal Zika Virus Infection in AG129 Mice

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Zika virus (ZIKV) infection causees neurologic complications, includingGuillain-Barré syndrome in adults and central nervous system (CNS) abnormalities in fetuses. We investigated the immune response, especially the CD8 ϩ T cell response in C57BL/6 (B6) wild-type (WT) mice, during ZIKV infection. We found that a robust CD8 ϩ T cell response was elicited, major histocompatibility complex class I-restricted CD8 ϩ T cell epitopes were identified, a tetramer that recognizes ZIKV-specific CD8 ϩ T cells was developed, and virus-specific memory CD8 ϩ T cells were generated in these mice. The CD8 ϩ T cells from these infected mice were functional, as evidenced by the fact that the adoptive transfer of ZIKV-specific CD8 ϩ T cells could prevent ZIKV infection in the CNS and was cross protective against dengue virus infection. Our findings provide comprehensive insight into immune responses against ZIKV and further demonstrate that WT mice could be a natural and easy-access model for evaluating immune responses to ZIKV infection.IMPORTANCE ZIKV infection has severe clinical consequences, including GuillainBarré syndrome in adults, microcephaly, and congenital malformations in fetuses and newborn infants. Therefore, study of the immune response, especially the adaptive immune response to ZIKV infection, is important for understanding diseases caused by ZIKV infection. Here, we characterized the CD8 ϩ T cell immune response to ZIKV in a comprehensive manner and identified ZIKV epitopes. Using the identified immunodominant epitopes, we developed a tetramer that recognizes ZIKVspecific CD8 ϩ T cells in vivo, which simplified the detection and evaluation of ZIKVspecific immune responses. In addition, the finding that tetramer-positive memory CD8 ϩ T cell responses were generated and that CD8 ϩ T cells can traffic to a ZIKVinfected brain greatly enhances our understanding of ZIKV infection and provides important insights for ZIKV vaccine design.KEYWORDS CD8 ϩ T cell, ZIKV, central nervous system, cross protection, immunocompetent mouse model Z ika virus (ZIKV) is a mosquito-transmitted flavivirus and a member of the Flaviviridae family of positive-stranded RNA enveloped viruses; the virus has also been found to be sexually and vertically transmitted (1). It was identified in 1947 in sentinel monkeys in Uganda (2). After its introduction into Brazil in 2015, ZIKV spread rapidly, both (i) causing a mild syndrome characterized by self-limiting fever, headache, myalgia, rash, and conjunctivitis and (ii) resulting in severe clinical consequences, including Guillain-

Section: Cd8 ϩ T Cell Immune Response In Zika Virus Infectionmentioning

confidence: 99%

CD8 ⁺ T Cell Immune Response in Immunocompetent Mice during Zika Virus Infection

Huang

Zhang

et al. 2017

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100

“…Mice lacking both the type I and type II IFN receptors (AG129) showed greater susceptibility and more severe disease following ZIKV infection (15,(27)(28)(29)(30)(31). By intradermal, subcutaneous, or intraperitoneal inoculation routes, infection with contemporary ZIKV strains from Cambodia, French Polynesia, or Puerto Rico was uniformly fatal in AG129 mice (15,27,31).…”

mentioning

confidence: 99%

Animal Models of Zika Virus Infection, Pathogenesis, and Immunity

Morrison

Diamond

2017

241

239

Zika virus (ZIKV) is an emerging mosquito-transmitted flavivirus that now causes epidemics affecting millions of people on multiple continents. The virus has received global attention because of some of its unusual epidemiological and clinical features, including persistent infection in the male reproductive tract and sexual transmission, an ability to cross the placenta during pregnancy and infect the developing fetus to cause congenital malformations, and its association with Guillain-Barré syndrome in adults. This past year has witnessed an intensive effort by the global scientific community to understand the biology of ZIKV and to develop pathogenesis models for the rapid testing of possible countermeasures. Here, we review the recent advances in and utility and limitations of newly developed mouse and nonhuman primate models of ZIKV infection and pathogenesis.

“…Several mouse models have been established to study ZIKV pathogenesis in immunocompetent, as well as immunodeficient, animals (for a review, see reference 33). Immunodeficient mice lacking the type I interferon (IFN) signaling pathways are highly susceptible to ZIKV infection (34)(35)(36)(37)(38)(39). A129 mice genetically lacking the IFN-␣/␤ receptor undergo significant body weight loss, show clinical disease with limb paralysis, and succumb to infection.…”

mentioning

confidence: 99%

Zika Virus Encoding Nonglycosylated Envelope Protein Is Attenuated and Defective in Neuroinvasion

Annamalai

Pattnaik

Sahoo

et al. 2017

111

Zika virus (ZIKV), a mosquito-transmitted flavivirus responsible for sporadic outbreaks of mild and febrile illness in Africa and Asia, reemerged in the last decade causing serious human diseases, including microcephaly, congenital malformations, and Guillain-Barré syndrome. Although genomic and phylogenetic analyses suggest that genetic evolution may have led to the enhanced virulence of ZIKV, experimental evidence supporting the role of specific genetic changes in virulence is currently lacking. One sequence motif, VNDT, containing an N-linked glycosylation site in the envelope (E) protein, is polymorphic; it is absent in many of the African isolates but present in all isolates from the recent outbreaks. In the present study, we investigated the roles of this sequence motif and glycosylation of the E protein in the pathogenicity of ZIKV. We first constructed a stable full-length cDNA clone of ZIKV in a novel linear vector from which infectious virus was recovered. The recombinant ZIKV generated from the infectious clone, which contains the VNDT motif, is highly pathogenic and causes lethality in a mouse model. In contrast, recombinant viruses from which the VNDT motif is deleted or in which the N-linked glycosylation site is mutated by single-amino-acid substitution are highly attenuated and nonlethal. The mutant viruses replicate poorly in the brains of infected mice when inoculated subcutaneously but replicate well following intracranial inoculation. Our findings provide the first evidence that N-linked glycosylation of the E protein is an important determinant of ZIKV virulence and neuroinvasion.IMPORTANCE The recent emergence of Zika virus (ZIKV) in the Americas has caused major worldwide public health concern. The virus appears to have gained significant pathogenicity, causing serious human diseases, including microcephaly and Guillain-Barré syndrome. The factors responsible for the emergence of pathogenic ZIKV are not understood at this time, although genetic changes have been shown to facilitate virus transmission. All isolates from the recent outbreaks contain an N-linked glycosylation site within the viral envelope (E) protein, whereas many isolates of the African lineage virus lack this site. To elucidate the functional significance of glycosylation in ZIKV pathogenicity, recombinant ZIKVs from infectious clones with or without the glycan on the E protein were generated. ZIKVs lacking the glycan were highly attenuated for the ability to cause mortality in a mouse model and were severely compromised for neuroinvasion. Our studies suggest glycosylation of the E protein is an important factor contributing to ZIKV pathogenicity.