Gallocatechin Gallate Inhibits the Replication of Pseudorabies Virus via Suppressing the Entry and Release Stages in Its Replication Cycle

SIMPLE SUMMARY: The development of antiviral compounds is an important method for preventing virus infection. The pseudorabies virus (PRV), one kind of alpha-herpesvirus, which can induce lytic and latent infection in pigs, causes huge economic losses to the Asian swine industry. Not only pigs but also multiple species of infection hosts of PRV have been reported, such as horses, bats, wolves, mice, cattle, etc. More crucially, it has been shown that the pseudorabies virus might be transmitted to human beings from infected animals. However, anti-PRV drugs have been rarely studied. In this study, a library of natural compounds was screened using an EGFP-labeled PRV, and the results showed that gallocatechin gallate, which is an extract from green tea, could significantly inhibit the replication of PRV in a dose-dependent manner. Finally, it was demonstrated that the entry and release stages of the PRV replication cycle were significantly suppressed by gallocatechin gallate. This study offers a new venture for the development of treatments against pseudorabies disease. ABSTRACT: The pseudorabies virus is a widespread swine pathogen that has caused significant economic losses to the global pig industry. Due to the emergence of PRV variant strains in recent years, vaccines cannot provide complete protection against the infection of PRV. Therefore, the research on antiviral compounds is of great importance for PRV treatment. In this study, an EGFP-labeled PRV was used to screen anti-PRV compounds from 86 natural product extracts. Gallocatechin gallate was found to efficiently inhibit the replication of PRV with a half-maximal inhibitory concentration (IC(50)) of 0.41 μM. In addition, it was found that gallocatechin gallate was unable to directly inactivate PRV and had no effect on the attachment stage of PRV. However, it was found that gallocatechin gallate significantly suppressed the viral entry stage. Furthermore, it was found that the release stage of PRV was also significantly suppressed by gallocatechin gallate. Together, this study found that gallocatechin gallate could efficiently inhibit the replication of PRV by suppressing the entry and release stages of PRV, which will contribute to the development of a new therapeutic strategy against PRV infection.