Chikungunya – one small step for a virus, one giant pandemic for mankind
Chikungunya virus (CHIKV) is an emerging mosquito-transmitted alphavirus associated with several recent large-scale epidemics of arthritic disease, including one on Reunion island, where there were approximately 266,000 cases (34% of the total island population). The large-scale epidemic of CHIKV began in Kenya in 2004 and spread to several Indian Ocean islands including the Comoros, Mauritius, the Seychelles, Madagascar, Mayotte and Reunion. On Reunion island alone there were approximately 266,000 cases (34% of the total island population). In the continuing Indian epidemic there have been at least 1.4 million cases reported with continued expansion in Sri Lanka and Indonesia. CHIKV had not been reported to cause fatalities in prior outbreaks; however, during the outbreak on Reunion island, CHIKV was associated with at least 260 deaths. The strain of CHIKV responsible for the Indian Ocean island epidemic has been well-characterized in cell culture and mosquito models; however, the underlying genetic basis of the atypical phenotype of this CHIKV strain remains unknown.
CHIKV is transmitted by Aedes species mosquitoes, primarily Ae. aegypti. However, the 20052006 CHIKV epidemic on Reunion island was unusual because the vector responsible for transmission between humans was apparently the Asian tiger mosquito, Ae. albopictus. Interestingly, the same epidemic was associated with a strain of CHIKV with a single amino acid mutation in the envelope protein gene (E1-A226V). In this paper the authors investigated the role of the E1-A226V mutation on the fitness of CHIKV in Ae. aegypti and Ae. albopictus mosquitoes. They found that E1-A226V is directly responsible for CHIKV adaptation to Ae. albopictus mosquitoes, which provides a plausible explanation of how this mutant virus caused an epidemic in a region lacking the typical vector. The observation that a single amino acid substitution can influence vector specificity provides a plausible explanation of how this mutant virus caused an epidemic in a region lacking the typical vector. This has important implications with respect to how viruses may establish a transmission cycle when introduced into a new area. Due to the widespread distribution of Ae. albopictus, this mutation increases the potential for CHIKV to permanently extend its range into Europe and the Americas.
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- Chikungunya, an epidemic arbovirosis
- Changing patterns of chikungunya virus
- Chikungunya pandemic reaches Europe
- Latest publications
Tags: Biology, Emerging disease, Health, Medicine, Microbiology, Science, Virology
