VN August 2022

Vetnuus | August 2022 38 Back to the future with Ivermectin, an antiparasitic drug developed in nineteenvoetsek is back with a bang! Not only was it proposed as an antiviral medication for the revered COVID-19, but multiple viruses across various species. Recent studies have demonstrated a dose-dependent effect against Bovine Herpesvirus 1 (BHV-1), and this article will briefly describe the mechanism of action of the antiviral effect ivermectin has against BHV-1 infection. BHV-1 causes a potential array of clinical diseases, ranging from reproductive disease and encephalitis to respiratory disease. The latter, the most essential and clinical disease, is termed Infectious Bovine Rhinotracheitis (IBR). BHV-1 is considered the primary viral pathogen in the Bovine Respiratory Disease Complex (BRDC), responsible for massive economic losses to the beef industry worldwide. Vaccination and proper management provide valuable tools to decrease morbidity and mortality. Although antimicrobials can potentially treat the bacterial fraction of BRD, there are currently no commercially available, effective antiviral drugs against the common BRD viruses. BHV-1 is a double-stranded DNA virus with the nuclear material encased in a protein capsid, which in turn is enveloped in a lipid membrane that is dispersed with spike proteins. Let's consider a swift view of the Herpesvirus life cycle: Viral spike proteins attach to the host cell membrane, enabling the virus to enter the cell. Once in the cell, the viral genome enters the cell nucleus and uses cellular and viral material to replicate itself. If the replication cycle is complete, the DNA gets encased in protein capsids and buds through the cellular membranes, creating viral envelopes. Infected cells undergo programmed cell death (apoptosis) and release numerous infective extracellular viruses (virions), infecting nearby cells and repeating the cycle. A closer look needs to be taken at viral DNA replication to explain the antiviral effect of Ivermectin. Inside the cell's nucleus, the DNA polymerase holoenzyme (DNA polymerase) is responsible for viral genome replication. The holoenzyme is, however, formed in the cytoplasm, outside the cell's nucleus, and needs to be transported into the nucleus via an assisted transport process. Large protein molecules, such as DNA polymerase, enter the nucleus via a Nuclear Pore Complex (NPC), with the assistance of another protein called an importin. To simplify this, you can visualise the outside of the nucleus (cytoplasm) as the ground level of a building and the inside of the nucleus (karyoplasm) as the first level of the same building. Regulars I Zoetis Livestock Column Zoetis Animal HealthPages FOR ANIMALS. FOR HEALTH. FOR YOU. Antiviral Effect of IvermectinAgainst BHV-1 Schabort Froneman Zoetis South Africa (Pty) Ltd Technical Manager: Ruminants