Jun-Gyu Park1†, Mia Madel Alfajaro1†, Eun-Hyo Cho1, Ji-Yun Kim1, Mahmoud Soliman1, Yeong-Bin Baek1, Chul-Ho Park2, Ju-Hwan Lee2, Kyu-Yeol Son1,3, Kyoung-Oh Cho1* and Mun-Il Kang1*
1 Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea. 2 Chonnam National University Veterinary Teaching Hospital, Gwangju 500‑757, Republic of Korea. 3 Choong Ang Vaccine Laboratory, Daejeon, Republic of Korea
†Jun-Gyu Park and Mia Madel Alfajaro are equal contributors
Porcine rotaviruses cause severe economic losses in the Korean swine industry due to G- and P-genotype mismatches between the predominant field and vaccine strains. Here, we developed a live attenuated trivalent porcine group A rotavirus vaccine using 80 cell culture passages of the representative Korean predominant strains G8P 174-1, G9P PRG942, and G5P K71. Vaccination with the trivalent vaccine or its individual components induced no diarrhea during the first 2 weeks post-vaccination, i.e., the vaccines were attenuated. Challenge of trivalent-vaccinated or component-vaccinated piglets with homologous virulent strain(s) did not induce diarrhea for 2 weeks post-challenge. Immunization with the trivalent vaccine or its individual components also alleviated the histopathological lesions in the small intestines caused by challenge with the corresponding original virulent strain(s). Fecal secretory IgAs specific for each of vaccine strains were detected starting at 14 days post-vaccination (dpv), and IgA levels gradually increased up to 28 dpv. Oral immunization with the trivalent vaccine or its individual components induced high levels of serum virus-neutralizing antibody by 7 dpv. No diarrhea was observed in any experimental piglets during five consecutive passages of each vaccine strain. Our data indicated that the live attenuated trivalent vaccine was safe and effective at protecting piglets from diarrhea induced by challenge exposure of homologous virulent strains. This trivalent vaccine will potentially contribute toward controlling porcine rotavirus disease in South Korea and other countries where rotavirus infections with similar G and P genotypes are problematic.