Primary infection with a Brazilian chikungunya virus isolate protects immunocompetent mice against detectable viremia following homologous rechallenge.

Chikungunya virus (CHIKV) is an arthropod-borne virus responsible for an acute febrile illness characterized by severe polyarthralgia, predominantly affecting peripheral joints. In a substantial proportion of patients, these symptoms may progress to chronic manifestations that significantly impair quality of life. Animal models are therefore critical for the development of effective therapeutic and preventive strategies, including antiviral agents and vaccines. In this context, the aim of this study was to establish an experimental model of CHIKV infection using immunocompetent C57BL/6 mice. Animals were infected with CHIKV and subsequently monitored for clinical signs, viremia, viral dissemination across tissues, total leukocyte counts, and susceptibility to reinfection. Results revealed no deaths among the animals during the experimental period, and infected animals exhibited significant viremia as well as detectable viral loads in the popliteal lymph node, femoral bone marrow, and muscle, demonstrating CHIKV capacity to disseminate and reach multiple target tissues. In addition, a global reduction in leukocyte counts was observed in infected mice. Notably, animals previously infected with CHIKV were resistant to reinfection, indicating the establishment of a protective immune response, as evidenced by the presence of neutralizing antibodies. In conclusion, the murine model established in this study recapitulates key features of CHIKV infection and provides a robust platform for investigating viral pathogenesis, as well as for evaluating novel antiviral strategies and vaccine candidates.