Heat shock enhances the susceptibility of BHK cells to rotavirus infection through the facilitation of entry and post-entry virus replication steps.

Rotavirus infection is known to induce several cellular stress proteins, although their possible involvement in the replication cycle of the virus has not been studied. In addition, the heat shock cognate protein hsc70 has been shown to function as a post-attachment receptor during virus entry. In this work we have studied the effect of heat shock on the susceptibility of cells to rotavirus infection. BHK cells, which are largely refractory to the virus, became about 100-fold more susceptible when heat-treated, while the rotavirus highly susceptible MA104 cells did not significantly modified their susceptibility upon heat stress, suggesting that heat shock induces factors that are rate-limiting the replication of rotaviruses in BHK but not in MA104 cells. The heat treatment was shown to facilitate the rotavirus infection of BHK cells at the penetration and post-penetration levels, and each of these stages seems to contribute comparably to the overall observed 100-fold increase in infectivity. Since the binding of the virus to the cell surface was not affected, the caloric stress probably facilitates the penetration and/or uncoating of the virus. The pathway of virus entry into heat-shocked BHK cells seems to be similar to that used in MA104 cells, since treatments that affect MA104 cell infection also affected rotavirus infectivity in heat-treated BHK cells.