Relationship between heat shock protein levels and infectivity in Trichinella spiralis larvae exposed to different stressors.

The aim of the present study was to investigate the relationship between infectivity and the levels of two major heat shock proteins (Hsp70 and Hsp60) in Trichinella spiralis larvae. Parasites were exposed to either sublethal thermal stress (43 and 45 degrees C) or to warm or cold temperature oxidative stress. The stressed larvae were then inoculated into female CD1 mice to determine their infectivity. Hsps were detected and quantified by Western blotting using monoclonal antibodies. Infectivity was expressed as larvae per gram of muscle. Warm temperature oxidative stress (20 mM H2O2 at 37 degrees C) caused a significant increase in Hsp levels and total loss of infectivity. Cold oxidative stress (20 mM H2O2 at 4 degrees C) caused no alterations in either Hsp levels or infectivity. However, high oxidative stress and cold (200 mM H2O2 at 4 degrees C) caused a slight increase in Hsp60 levels and a drastic reduction in infectivity. Exposure of the larvae to 43 or 45 degrees C did not significantly alter Hsp levels or infectivity. These results show that (i) cold reduces the deleterious effects of oxidative stress; (ii) heat induces neither increased Hsp60/Hsp70 levels nor reduces infectivity; (iii) increased Hsp levels induced by oxidative stress may cause lower infectivity.