Interaction dynamics of Borrelia afzelii and tick-borne encephalitis virus in C3H mice: insights into immune response

Ticks are important vectors responsible for transmitting a wide range of diseases that have significant impacts on both human and animal health. In Europe, the Ixodes tick is especially remarkable for its ability to spread pathogens such as Borrelia , the bacterium that causes Lyme disease, and the tick-borne encephalitis virus (TBEV), which can lead to serious neurological infections. Building on the results of our previous research involving co-infection with Borrelia afzelii and TBEV in C3H mice, this study aimed to further investigate the interactions between these two pathogens, focusing on the timing of infection and examining mRNA cytokine levels in the brain and spleen of both single- and co-infected mice and their possible link to the clinical outcome. The results revealed that the timing of infection significantly influenced the immune response, highlighting the complex interactions between B. afzelii and TBEV. B. afzelii infection can influence TBEV dynamics, either amplifying or suppressing its effects depending on the timing of infection. In addition, this study helps to better understand how the immune system reacts when both TBEV and B. afzelii infect a host under different conditions. It sheds light on how these pathogens interact and affect disease progression.