부산대학교 도서관

Infections with Chikungunya virus, a mosquito-borne alphavirus, cause an acute febrile syndrome often followed by chronic arthritis that persists for months to years post infection. Neutralizing antibodies are the primary immune correlate of protection elicited by infection, and the major goal of vaccinations in development. Using convalescent blood samples collected from both endemic and non-endemic human subjects at multiple timepoints following suspected or confirmed chikungunya infection, we identified antibodies with broad neutralizing properties against other alphaviruses within the Semliki Forest complex. Cross-neutralization generally did not extend to the Venezuelan Equine Encephalitis virus (VEEV) complex, although some subjects had low levels of VEEV-neutralizing antibodies. This suggests that broadly neutralizing antibodies elicited following natural infection are largely complex restricted. In addition to serology, we also performed memory B-cell analysis, finding chikungunya-specific memory B-cells in all subjects in this study as remotely as 24 years post-infection. We functionally assessed the ability of memory B-cell derived antibodies to bind to chikungunya virus, and related Mayaro virus, as well as the highly conserved B domain of the E2 glycoprotein thought to contribute to cross-reactivity between related Old-World alphaviruses. To specifically assess the role of the E2 B domain in cross-neutralization, we depleted Mayaro and Chikungunya virus E2 B domain specific antibodies from convalescent sera, finding E2B depletion significantly decreases Mayaro virus specific cross-neutralizing antibody titers with no significant effect on chikungunya virus neutralization, indicating that the E2 B domain is a key target of cross-neutralizing and potentially cross-protective neutralizing antibodies. Author summary: The emergence and re-emergence of alphaviruses as important human pathogens raises questions about the durability and breadth of alphavirus immunity following natural infection in humans. In this study, we examine human immune sera from twelve individuals infected (up to 24 years) previously with chikungunya virus and test the sera against a panel of five Old-World arthritogenic alphaviruses and one New-World encephalitic alphavirus. Both homotypic and cross-reactive memory B-cells were identified in subjects out to 24 years post infection. Our results indicate that infection with chikungunya virus results in a robust and durable cross-reactive humoral immune response. Such a response could potentially provide immunity against repeat infection with chikungunya as well as related alphaviruses for years to decades after initial infection. This cross-reactivity might contribute to restricted transmission of closely related alphaviruses and indicates the potential for chikungunya candidate vaccines to elicit broad protection against other alphaviruses in the Semliki Forest complex. [ABSTRACT FROM AUTHOR]