Abstract

The Chikungunya virus (CHIKV) belongs to the Alphavirus genus of Togaviridae family and contains a positive-sense single stranded RNA genome. Infection by this virus mainly causes sudden high fever, rashes, headache, and severe joint pain that can last for several months or years. CHIKV, a mosquito- borne arbovirus, is considered a re-emerging pathogen that has become one of the most pressing global health concerns due to a rapid increase in epidemics. Because handling of CHIKV is restricted to Biosafety Level 3 (BSL-3) facilities, the evaluation of prophylactic vaccines or antivirals has been substantially hampered. In this study, we first identified the whole structural polyprotein sequence of a CHIKV strain isolated in South Korea (KNIH/2009/77). Phylogenetic analysis showed that this sequence clustered within the East/ Central/South African CHIKV genotype. Using this sequence information, we constructed a CHIKV-pseudotyped lentivirus expressing the structural polyprotein of the Korean CHIKV isolate (CHIKVpseudo) and dual reporter genes of green fluorescence protein and luciferase. We then developed a pseudovirus-based neutralization assay (PBNA) using CHIKVpseudo. Results from this assay compared to those from the conventional plaque reduction neutralization test showed that our PBNA was a reliable and rapid method to evaluate the efficacy of neutralizing antibodies. More importantly, the neutralizing activities of human sera from CHIKVinfected individuals were quantitated by PBNA using CHIKVpseudo. Taken together, these results suggest that our PBNA for CHIKV may serve as a useful and safe method for testing the neutralizing activity of antibodies against CHIKV in BSL-2 facilities.

• Keywords: Chikungunya virus; Korean isolate; Pseudovirus; Neutralization assay; Human serum