Antiviral effect of ivermectin on the bovine alphaherpesvirus 1 infection in bovine

Objetive. Conventional control measures for rhinotracheitis caused by bovine alphaherpesvirus 1 (BoAHV-1, IBR) include vaccination and hygienic measures for herd cattle. In this study, an antiparasitic (Ivermectin) drug was evaluated for the potential treatment of BoAHV-1 in bovines. Materials and Methods. Fifteen bovines were randomly assigned to three groups (n=5 per group). Group 1 received no treatment. Group 2 was subcutaneously vaccinated with 3 mL of a commercial inactivated BoAHV-1 vaccine (Biopoligen Air) 30 and 9 days prior to viral challenge. Group 3 was treated with ivermectin (IVOMEC 1%, 0.2 mg/kg) at 0 and 5 days post-challenge. All animals were challenged intranasal with 3 mL of virulent BoAHV-1 (107.5 TCID₅₀/mL). Clinical signs were scored daily for 22 days post-challenge (dpc), and nasal secretions were collected for 14 dpc to assess viral shedding. Results. The efficacy of Ivermectin in inhibiting BoAHV-1 replication during peak infection days was notable, demonstrating a reduction of 1.5-2.25 logs compared to the infection control group. This inhibition was significant on day 6, coinciding with the peak excretion observed in the infection control group. Although replication was significantly reduced in animals challenged and treated with IVM, a question that was not answered is whether this replication was sufficient to establish latency. Therefore, it remains pending for future investigations to immunosuppress and evaluate the reactivation of latency. Conclusions. The findings of this study demonstrate that Ivermectin administered at the beginning of the infection and with reinforcement at 5 days was effective in reducing clinical signs of disease and viral excretion following the BoAHV-1 challenge. These findings demonstrate the inhibitory effect of ivermectin on BoAHV-1 replication in vivo and offer an alternative complementary strategy for managing and controlling BoAHV-1 outbreaks.