Humoral immunity of voles Cricetidae Rodentia in Siberia

We studied the seasonal variation of adaptive humoral immunity (AHI) in
northern red-backed vole (Clethrionomys rutilus Pallas, 1779, RBV) and
grey-sided vole (C. rufocanus Sundevall, 1846, GSV) in Tomsk region of
Western Siberia. Immunoresponsiveness (IR) to sheep red blood cells was
assessed by the number of antibody-producing cells in the spleen. The use
of a generalized linear model to analyze the effects of species, sex, year
of research, and season of withdrawal of individuals from nature on IR
showed a significant effect of species identity, season of animals capture
and the interaction of species with season. The RBV demonstrated higher
immune responses during a year, and both species had higher IR in winter.
Suppression of IR in spring was greater, started earlier and lasted longer
(March–May) in GSV. In RBV, immunosuppression was restricted to April. The
significant negative within year correlations of IR with body mass and
masses of reproductive organs in GSV a tradeoff between AHI and growth and
reproduction processes. A reason for the difference between species in the
seasonal variation of AHI may be related to the difference in
tropho-energetic requirements of each vole species. GSV is a predominantly
herbivorous rodent and its thermoregulation seems less efficient than of
RBV. The deeper spring immunosuppression in GSV may explain in part its
higher mortality during the season of colds.