Residues within the Foot-and-Mouth Disease Virus 3Dpol Nuclear Localization Signal Affect Polymerase Fidelity

Molecular characterization of VP1 gene during the foot and mouth disease virus outbreak in East Java, Indonesia, in 2022

Background and Aim

Foot and mouth disease (FMD) is highly contagious in cloven-hoofed animals, and it causes outbreaks in Indonesia and several countries worldwide. This disease is caused by the FMD virus (FMDV), which belongs to the genus Aphthovirus and family Picornaviridae. In 1990, the World Organization for Animal Health Office International des Epizooties recognized Indonesia as an FMD-free country. A new FMDV outbreak in Indonesia was reported in April 2022 and confirmed in May 2022, resulting in economic losses to the beef cattle sector. This study aimed to determine the genotype and amino acid content of viral proteins (VP1) gene.

Materials and Methods

Samples were obtained from vesicle swabs from the mouth and feet of cattle in Banyuwangi Regency, Lamongan Regency, and Surabaya City, East Java, Indonesia. Samples were identified using one-step reverse transcriptase-polymerase chain reaction with a pair of specific primers encoding the VP1O serotype with a target of 1165 bp.

Results

Sequencing revealed that the FMDV subtype belonged to the O/ME-SA/Ind2001e. Phylogenetic analysis showed that our isolate was 100% amino acid-identical to the Indonesian outbreak isolates from 2022 and 95% identical to isolates from Southeast Asia. The amino acid substitutions found in the G-H Loop of the VP1were S134C, D138E, T140A, and A156T. Only the K135Q mutation was detected in Lamongan.

Conclusion

The spread of the subtype O/ME-SA/Ind2001e in South-east Asia caused an outbreak in Indonesia due to less stringent animal traffic control measures. Surveillance studies and whole-genome sequence analyses are important for monitoring FMDV genetics in Indonesia.

Multiple functions of the nonstructural protein 3D in picornavirus infection

3D polymerase, also known as RNA-dependent RNA polymerase, is encoded by all known picornaviruses, and their structures are highly conserved. In the process of picornavirus replication, 3D polymerase facilitates the assembly of replication complexes and directly catalyzes the synthesis of viral RNA. The nuclear localization signal carried by picornavirus 3D polymerase, combined with its ability to interact with other viral proteins, viral RNA and cellular proteins, indicate that its noncatalytic role is equally important in viral infections. Recent studies have shown that 3D polymerase has multiple effects on host cell biological functions, including inducing cell cycle arrest, regulating host cell translation, inducing autophagy, evading immune responses, and triggering inflammasome formation. Thus, 3D polymerase would be a very valuable target for the development of antiviral therapies. This review summarizes current studies on the structure of 3D polymerase and its regulation of host cell responses, thereby improving the understanding of picornavirus-mediated pathogenesis caused by 3D polymerase.