Mutations in the E2 Glycoprotein and the 3′ Untranslated Region Enhance Chikungunya Virus Virulence in Mice

Abstract

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes debilitating musculoskeletal pain and inflammation and can persist for months to years after acute infection. Although studies in humans and experimentally-infected animals suggest that CHIKV infection persists in musculoskeletal tissues, the mechanisms for this remain poorly understood. To evaluate this further, we isolated CHIKV from the serum of persistently infected mice at day 28. When inoculated into naïve WT mice, this persistently circulating CHIKV strain displayed a capacity for earlier dissemination and greater pathogenicity compared with the parental virus. Sequence analysis revealed a nonsynonymous mutation in the E2 glycoprotein (E2 K200R) and a deletion within the 3' untranslated region (3' -UTR). Introduction of these changes into the parental virus conferred enhanced virulence in mice although a primary tropism for musculoskeletal tissues was maintained. The E2 K200R mutation was largely responsible for enhanced viral dissemination and pathogenicity, although these effects were augmented by the 3' -UTR deletion. Finally, studies in and mice suggest that the E2 K200R mutation enhances viral dissemination from the site of inoculation independently of IRF3, IRF7, and IFNAR1 mediated responses. As our findings reveal viral determinants of CHIKV dissemination and pathogenicity, their further study should help to elucidate host-virus interactions that determine acute and chronic CHIKV infection. CHIKV is a globally-spreading, mosquito-transmitted virus that causes debilitating acute and chronic musculoskeletal disease in humans. The viral genetic determinants that dictate acute and chronic disease severity are not understood. To improve our understanding of CHIKV pathogenesis, we evaluated a CHIKV strain isolated from the serum of chronically-infected immunocompromised mice. Sequence analysis of this persistent CHIKV strain identified two mutations, an amino acid change in the E2 viral attachment protein and a deletion within the 3' -UTR of the viral genome. We identified roles for these mutations in enhancement of viral dissemination from the inoculation site and in disease severity. These data improve our understanding of the viral determinants of CHIKV pathogenesis and adaptive changes that occur during viral persistence.

Chikungunya virus replication in skeletal muscle cells is required for disease development

“…CHIKV infection in humans results in a syndrome characterized by severe arthralgia and myalgia (29)(30)(31). Replication in skeletal muscle has been associated with development of severe disease (14,16,17), but the pathologic outcome of virus replication in muscle cells has not been well-defined. To understand the contribution of viral These hallmarks of human infection are recapitulated in a mouse model of CHIKV disease.…”

“…Virus then disseminates to a variety of sites of secondary replication, including cells of musculoskeletal tissues and the synovium (11,(13)(14)(15). Mounting evidence has implicated skeletal muscle as an important site in CHIKV disease development (14,16,17). CHIKV infection in humans results in myalgia in almost all patients (18)(19)(20)(21)(22).…”

Discrete viral E2 lysine residues and scavenger receptor MARCO are required for clearance of circulating alphaviruses

“…Previously, we identified a mutation in the CHIKV E2 glycoprotein (E2 K200R) in virus persistently circulating in Rag1 -/- mice (Hawman et al, 2017). This mutation enhanced CHIKV dissemination in mice following subcutaneous inoculation and caused more severe disease outcomes.…”

“…To define the viral features that mediated clearance of circulating alphavirus particles, we identified CHIKV and RRV strains that evade phagocytic cell-mediated clearance. CHIKV E2 K200R was isolated from the serum of a Rag1 -/- mouse chronically infected with an Asian genotype CHIKV strain (Hawman et al, 2017), suggesting that this mutation arose as a mechanism to evade phagocytic cell-mediated clearance from the circulation. Introduction of an E2 K200R mutation into CHIKV strains representative of the Asian-American, ECSA, and West African CHIKV clades also facilitated escape of viral particles from phagocytic cell-mediated clearance and enhanced viral dissemination following subcutaneous inoculation.…”

Genetic characterization of Chikungunya virus 2009 isolates from South India

“…A study proved that mutation in E2 gene leads to more severe inflammation and damage in the tissues distal to the site of the inoculation in the mice that were inoculated with CHIKV strain with mutation in E2 and in 3'UTR. Mutation in E2 along with 3'UTR enhances dissemination of virus to different organs with increases in titre of virus [ 19 ]. Since the recent outbreak is evidenced with severe joint pain in majority of the patients, it may be due to amino acid substitution in viral proteins, which leads to enhancement of host cell binding affinity.…”