Chikungunya virus transmission between Aedes albopictus and laboratory mice

Background: Chikungunya virus (CHIKV) is a mosquito-borne alphavirus associated with epidemics of acute and chronic arthritic disease in humans. Aedes albopictus has emerged as an important new natural vector for CHIKV transmission; however, mouse models for studying transmission have not been developed. Methods: Aedes albopictus mosquitoes were infected with CHIKV via membrane feeding and by using infected adult wild-type C57BL/6 mice. Paraffin sections of infected mosquitoes were analysed by immunofluorescent antibody staining using an anti-CHIKV antibody. CHIKV-infected mosquitoes were used to infect adult C57BL/6 and interferon response factor 3 and 7 deficient (IRF3/7(-/-)) mice. Results: Feeding mosquitoes on blood meals with CHIKV titres > 5 log(10)CCID(50)/ml, either by membrane feeding or feeding on infected mice, resulted in >= 50 % of mosquitoes becoming infected. However, CHIKV titres in blood meals >= 7 log(10)CCID(50)/ml were required before salivary glands showed significant levels of immunofluorescent staining with an anti-CHIKV antibody. Mosquitoes fed on blood meals of 7.5 (but not 5.9) log(10)CCID(50)/ml were able efficiently to transmit virus to adult C57BL/6 and IRF3/7(-/-) mice, with the latter mice showing overt signs of arthritis post-infection. Conclusions: The results provide a simple in vivo model for studying transmission of CHIKV from mosquitoes to mammals and also argue against a resistance barrier to CHIKV infection in adult mice.