The Antiviral Effect of Two Important Base Analogs, Ribavirin and 5-Fluoruracil, on Infectious Pancreatic Necrosis Virus

Infectious pancreatic necrosis (IPN) has highly contagious disease and an important viral disease-causing economic loss for fish farming, which has developed in recent years. The virus is the first fish virus isolated in vitro. Horizontal and vertical transmission plays an important role in the spread of the virus. In addition, the resistance of the virus to environmental conditions makes it difficult to control the virus. Therefore, it is important to develop vaccines and analyze the effectivity of antivirals for the prevention and control of infectious pancreatic necrosis virus (IPNV) infection. This study investigated the antiviral effect of two different mutagens, ribavirin (RBV) and 5-fluorouracil (5-FU), on IPNV, and their mutation-inducing potential on the susceptible cell line Epithelioma papulosum cyprini (EPC), in vitro. For this purpose, cytotoxic doses of RBV and 5-FU were first investigated and were found to be 50 and 100 µM/mL, respectively. Serial passages of IPNV were then performed, both with and without drug suppression. At the end of each passage, confirmation was performed by real-time transcriptase polymerase chain reaction (RT-PCR). Serial passages were checked for viral load using quantitative RT-PCR (qRT-PCR). The viral copy number of the RBV-suppressed virus decreased from 1.18 × 10⁵ copies/µL for the 1st passage to 1.49 × 10² copies/µL at the end of the 5th passage. The viral copy number of the 5-FU-suppressed virus decreased gradually with each passage, from 3.84 × 10³ copies/µL for the 1st passage to 1.78 × 10² copies/µL at the end of the 5th passage, with the exception of the 2nd passage, where the viral load increased. Passages 1st and 5th of both the RBV- and 5-FU-suppressed virus, and the non-drug-suppressed virus, were checked by partial sequence, but mutations in VP2 were not observed. In conclusion, in this study, we obtained data on the antiviral activity of two mutagens on IPNV.