Immunohistochemical comparative study between two strains of the Chikungunya virus in a mouse model

Chikungunya fever is a vector-borne disease caused by Chikungunya virus (CHIKV) that is transmitted mainly through the bite of Aedes aegypti and Aedes albopictus mosquito species. Nowadays there is no prophylaxis for CHIKV and it has been responsible of several major outbreaks since the 2000s such as La Réunion island outbreak in 2005. These diverse outbreaks have allowed the spread of the virus to different parts of the world to such an extent that autochthonous outbreaks have been confirmed in Europe. Climate change, imports from endemic areas and the adaptation of arboviruses to novel vectors could produce more outbreaks in the future and colonization of new places by mosquitoes carrying the virus. In this project, a comparative study between two different CHIKV strains (S27 and ITA1) in an IFN-α/β (-/-) receptor knock out mice model was carried out in order to characterize the tropism of the virus. Immunolabeling was found in joints (synovial capsule), fibrocytes (periosteum, epineurium, endo/perimysium, blood vessel's basal lamina, and dermis), macrophages (in the spleen, lymph nodes and liver's kupffer cells), endothelium, leptomeningeal cells and some foci in the glia of the encephalon, among others. However, nonspecific immunolabeling has also occurred in some control tissues requiring careful evaluation. The immunolabelling differences between the two strains were not very noticeable. Clinically, the S27 strain was more virulent and the ITA1 strain caused a greater lympholysis. The development of studies about the pathogenesis of different CHIKV strains in animal models helps obtaining a better understanding of the pathophysiology of the disease and, therefore, will be useful in the search for new therapies and vaccines to prevent and control the disease