Date Published: January 23, 2019
Publisher: Public Library of Science
Author(s): Supansa Tuanthap, Sompong Vongpunsawad, Supol Luengyosluechakul, Phanlert Sakkaew, Apiradee Theamboonlers, Alongkorn Amonsin, Yong Poovorawan, Humberto Rodney Colina Muñoz.
Rotavirus A (RVA) infection is a major cause of diarrhea-related illness in young children. RVA is also one of the most common enteric viruses detected on pig farms and contributes to substantial morbidity and mortality in piglets. Long-term multi-site surveillance of RVA on Thai swine farms to determine the diversity of RVA strains in circulation is currently lacking. In this study, we characterized the 11 segments of the RVA genome from 24 Thai porcine RVA strains circulating between 2011 and 2016. We identified G9 (15/24) and P (12/24) as the dominant genotypes. The dominant G and P combinations were G9P (n = 6), G9P (n = 6), G3P (n = 5), G9P (n = 3), G4P (n = 2), G4P (n = 1), and G5P (n = 1). Genome constellation of the Thai strains showed the predominance of Wa-like genotype (Gx-P[x]-I1/I5-R1-C1-M1-A8-N1-T1/T7-E1/E9-H1) with evidence of reassortment between the porcine and human RVA strains (e.g., G4-P-I1-R1-C1-M1-A8-N1-T1-E1-H1 and G9-P-I5-R1-C1-M1-A8-N1-T7-E9-H1). To assess the potential effectiveness of rotavirus vaccination, the Thai RVA strains were compared to the RVA strains represented in the swine rotavirus vaccine, which showed residue variations in the antigenic epitope on VP7 and shared amino acid identity below 90% for G4 and G5 strain. Several previous studies suggested these variations might effect on virus neutralization specificity and vaccine efficacy. Our study illustrates the importance of RVA surveillance beyond the G/P genotyping on commercial swine farms, which is crucial for controlling viral transmission.
Rotavirus is highly contagious and is frequently responsible for acute gastroenteritis in humans and animals. It is a major cause of diarrhea-associated childhood hospitalization for children younger than 5 years of age . On swine farms, rotavirus A (RVA) infection contributes to a substantial economic loss . Complicating management and control of RVA infection are an unpredictable pattern of outbreaks, unknown passive immunity within the nursing herds, feasibility of mass vaccination, and co-infection with other enteric viral pathogens. Therefore, RVA infection remains an important threat to the pig industry.
Awareness of RVA infection on Thai swine farms are currently insufficient to appreciate the magnitude of viral circulation and the emergence of potentially novel viral reassortants. To better understand the genetic and antigenic relationship of circulating porcine RVA within Thailand and in comparison to the global and vaccine strains, we characterized the genome constellation of 24 Thai RVA strains from among the RVA-positive samples in our previous study . In addition to G/P genotyping, the analysis of near-complete and partial gene regions of the non-G/P segments revealed inter-species RVA reassortants and the genetic diversity of RVA circulating on medium-to-large commercial Thai swine farms (S1 Fig).