Journal of Antivirals & Antiretrovirals
Open Access

Abstract

Antiviral Activity of Tilmicosin for Type 1 and Type 2 Porcine Reproductive And Respiratory Syndrome Virus In Cultured Porcine Alveolar Macrophages

Yijun Du, Dongwan Yoo, Marie Anne Paradis and Gail Scherba

Tilmicosin was investigated in a stable porcine alveolar macrophage cell line for its antiviral activity against types 1 and 2 porcine reproductive and respiratory syndrome virus (PRRSV). Tilmicosin exhibited strong antiviral effects on both genotypes of PRRSV replication in cultured porcine alveolar macrophages. The antiviral activity was more potent for type 1 PRRSV as indicated by reduction in infectious virus yield of nearly 43-fold for type 1 as compared to 14-fold for type 2. Real-time RT-PCR for detection of viral nucleocapsid gene confirmed the reduction of infectious virus titer in the presence of tilmicosin. Lysosomotropic and ion-channel blocking agents efficiently inhibited PRRSV replication, suggesting that the antiviral mechanism of tilmicosin is likely associated with the alteration of endosomal pH and possibly the ion-channel activity on the viral membrane. This study indicates that tilmicosin may have potential as an early treatment or preventative measure against PRRSV infections, especially for areas where the type 1 genotype is prevalent.