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Pseudorabies virus (PrV), a member of alpha-herpesviruses, is one of the most significant viral pathogens for swine. We had successfully purified virions of PrV by sucrose centrifugation gradient. With Kpn I restriction enzyme digestion of viral DNA and Western blot of viral glycoprotein E , it was demonstrated that mature PrV virions were located in fraction IV of sucrose gradient. Initially, actin was found in fraction II, III and IV of gradient. In order to know the location of actin, virions were treated either with trypsin to digest the polypeptide moiety outside the viral envelope or with detergent Triton X-100 to remove the envelope of PrV prior to Western blotting. And we found that viral associated actin was resistant to trypsin digestion, indicating that actin is located inside the virion. To understand how actin plays a role in PrV life cycle, we added cytochalasin D, a drug inhibiting F actin formation, to PrV- infected MDBK cells, then the plaque formation of PrV was examined. The results showed that cytochalasin D could reduce the size and number of PrV plaques in MDBK cells. On the other hand, we also found that heat shock proteins 70 ( HSP70 ) were present in all three fractions and the extracellular-regulated kinase 2 ( ERK- 2 ) could be detected in fraction II and III. Following Triton treatment, the heat shock protein was not detectable by Western blotting, suggesting that it was outside to the viral envelope. Taken together, our results suggested that certain cellular proteins may play important roles in PrV life cycle.
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