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Browsing by Author "Savolainen, Kia"

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  • Savolainen, Kia (2019)
    Co-­infection, a state in which the host is infected with more than one micro-­ or macroparasite at a time, is the norm in the wild because of a wide range of interacting organisms and parasites. Bank vole is a reservoir host of Puumala hantavirus (PUUV), a pathogen causing Nephropathia Endemica, an endemic disease in Finland. The helper T cell (Th)1/Th2 polarization theory, which is established in the laboratory, but less-­studied in the wild, suggests that there is a trade-­off between Th1 response against microparasites and Th2 response against macroparasites. I studied whether helminth or hantavirus infection, individually and synergistically, have effect on the immune responses of wild bank voles and whether there is a trade-­off between Th1 and Th2 responses. My hypothesis was that helminth infection would reduce the bank voles’ ability to mount an effective immune response against viral infections and make them more susceptible to chronic Puumala virus infection. I measured mRNA levels of transcription factors Tbet (Th1 response) and Gata3 (Th2 response) in the splenocytes of wild-­caught bank voles after stimulating the cells with different immune stimulants. I also measured the constitutive levels of Tbet and Gata3 in bank voles’ spleens. The splenocytes of PUUV-­infected bank voles were less responsive to stimulations than those of PUUV-­negative ones. The reduced ability of splenocytes from PUUV-­infected voles to respond to stimulation can be because of the virus itself affecting the T cell function or alternatively due to an inherent defect in immune cells making them more susceptible to PUUV infection. The constitutive expression of Gata3 in spleen correlated positively with gastrointestinal nematode load in PUUV-­infected voles but not in PUUV-­negative voles. This can be because of mounting an immune response against helminths reduces the bank voles’ ability to resist the viral infection in accordance with the trade-­off between Th1 and Th2 responses or as previous studies have shown, Gata3 can act as a marker of infection tolerance in bank voles. Because of a small sample size and a heterologous group of studied bank voles, more research is needed on co-­infection immunology in bank voles and other wild animals.