Abstract
ABSTRACTChikungunya virus (CHIKV) is a reemerging arbovirus capable of causing explosive outbreaks of febrile illness, polyarthritis, and polyarthralgia, inflicting severe morbidity on affected populations. CHIKV can be genetically classified into 3 major lineages: West African (WA); East, Central, and South African (ECSA); Indian Ocean (IOL); and Asian. Additionally, the Indian Ocean (IOL) sublineage emerged within the ECSA clade and the Asian/American sublineage emerged within the Asian clade. While differences in epidemiological and pathological characteristics among outbreaks involving different CHIKV lineages and sublineages have been suggested, few targeted investigations comparing lineage virulence levels have been reported. We compared the virulence levels of CHIKV isolates representing all major lineages and sublineages in the type I interferon receptor-knockout A129 mouse model and found lineage-specific differences in virulence. We also evaluated the cross-protective efficacy of the IOL-derived, live-attenuated vaccine strain CHIKV/IRESv1 against the Asian/American CHIKV isolate YO123223 in both murine and nonhuman primate models, as well as the WA strain SH2830 in a murine model. The CHIKV/IRES vaccine provided protection both in mice and in nonhuman primate cohorts against Caribbean strain challenge and protected mice against WA challenge. Taken together, our data suggest that Asian/American CHIKV strains are less virulent than those in the Asian, ECSA, and WA lineages and that despite differences in virulence, IOL-based vaccine strains offer robust cross-protection against strains from other lineages. Further research is needed to elucidate the genetic basis for variation in CHIKV virulence in the A129 mouse model and to corroborate this variation with human pathogenicity.
Highlights
IMPORTANCE Chikungunya virus (CHIKV) is a reemerging human pathogen capable of causing debilitating and disfiguring polyarthritis, which can last for months to years after initial fever has resolved
All mice succumbed to West African (WA) strain infection by 4 days postinfection (DPI), while mice infected with Indian Ocean lineage (IOL) and ECSA strains succumbed by days 4 and 5, respectively
WA strains collectively appeared to be more virulent, with mice universally succumbing to infection within 4 days, while almost 50% of mice survived to day 5 after infection with an Asian/American (Caribbean) strain
Summary
IMPORTANCE Chikungunya virus (CHIKV) is a reemerging human pathogen capable of causing debilitating and disfiguring polyarthritis, which can last for months to years after initial fever has resolved. We sought to compare the virulence levels among CHIKV lineages, as well as to evaluate the cross-protective efficacy of the CHIKV/IRESv1 vaccine candidate, in two different models of CHIKV infection. Chikungunya virus (CHIKV), an important human pathogen in the family Togaviridae, genus Alphavirus, is the etiologic agent of chikungunya fever (CHIKF), which is marked by a sudden onset of high fever, rash, and polyarthritis/polyarthralgia This polyarthritis may last months to years after infection, causing significant financial as well as public health burdens. The most important clades in terms of public health impact are the Asian lineage (including Asian/American) and the IOL sublineage, as well as some other ECSA lineage strains responsible for African outbreaks.
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