ZIKV-Specific NS1 Epitopes as Serological Markers of Acute Zika Virus Infection.

BACKGROUND: Zika virus (ZIKV) infections have reemerged as a global health issue due to serious clinical complications. Development of specific serological assays to detect and differentiate ZIKV from other cocirculating flaviviruses for accurate diagnosis remains a challenge. METHODS: We investigated antibody responses in 51 acute ZIKV-infected adult patients from Campinas, Brazil, including 7 pregnant women who later delivered during the study. Using enzyme-linked immunosorbent assays, levels of antibody response were measured and specific epitopes identified. RESULTS: Several antibody-binding hot spots were identified in ZIKV immunogenic antigens, including membrane, envelope (E) and nonstructural protein 1 (NS1). Interestingly, specific epitopes (2 from E and 2 from NS1) strongly recognized by ZIKV-infected patients' antibodies were identified and were not cross-recognized by dengue virus (DENV)-infected patients' antibodies. Corresponding DENV peptides were not strongly recognized by ZIKV-infected patients' antibodies. Notably, ZIKV-infected pregnant women had specific epitope recognition for ZIKV NS1 (amino acid residues 17-34), which could be a potential serological marker for early ZIKV detection. CONCLUSIONS: This study identified 6 linear ZIKV-specific epitopes for early detection of ZIKV infections. We observed differential epitope recognition between ZIKV-infected and DENV-infected patients. This information will be useful for developing diagnostic methods that differentiate between closely related flaviviruses.

VCP/p97 Is a Proviral Host Factor for Replication of Chikungunya Virus and Other Alphaviruses.

The evolutionarily conserved AAA+ ATPase valosin-containing protein (VCP) was previously shown to be a proviral host factor for several viruses from different viral families such as Flaviviridae, Picornaviridae, and Herpesviridae. VCP was shown to affect trafficking of Sindbis virus receptor and functions as a component of Semliki Forest virus (SFV) replicase compartment. However, the role of this cellular protein was not evaluated during replication of alphaviruses including chikungunya virus (CHIKV). Using siRNA, chemical inhibitors, and trans-replication assays, we show here that VCP is a proviral factor involved in the replication of CHIKV. Immunofluorescence assays confirmed that VCP co-localized with non-structural replicase proteins but not with dsRNA foci possibly due to VCP epitope unavailability. VCP pro-viral role is also observed with other alphaviruses such as o'nyong'nyong virus (ONNV) and SFV in different human cell lines. VCP proviral roles on several viral families now extend to replication of alphaviruses CHIKV and ONNV, emphasizing the pivotal role of VCP in virus-host interaction biology.