Blood stress protein levels in relation to sex and parasitism of barn swallows (Hirundo rustica)

We investigated the presence and levels of two different heat shock proteins in the blood of adult male and female barn swallows (Hirundo rustica) infected by haemoparasites in a breeding population from southwestern Spain during 1997. Three blood parasites (microfilaria, Trypanosoma sp., and Haemoproteus prognei) infected swallows from this population. HSP60 and HSP70 were detected, and their abundance was positively related. In a paired comparison between birds of the same sex, breeding site, and date of capture, infected birds showed significantly higher levels of HSP60 than did uninfected controls Among uninfected birds, males showed higher levels than females, but infected birds of either sex had higher levels of this protein than uninfected individuals These differences may be related to higher susceptibility of males to infection and the protective characteristics of HSPs. Based on known properties of HSPs, we suggest that higher levels of HSP60 may buffer the effects of infection in the sex showing lower immunity.