Experimental infection of pigs with a classical swine fever virus isolated in Japan for the first time in 26 years

• Published in: Journal of Veterinary Medical Science Vol. 81; no. 9; pp. 1277 - 1284
• Main Authors: KAMEYAMA, Ken-ichiro, NISHI, Tatsuya, YAMADA, Manabu, MASUJIN, Kentaro, MORIOKA, Kazuki, KOKUHO, Takehiro, FUKAI, Katsuhiko
• Format: Journal Article
• Language: English
• Published: Japan JAPANESE SOCIETY OF VETERINARY SCIENCE 2019; Japan Science and Technology Agency; The Japanese Society of Veterinary Science
• Subjects: Animals; Antibodies, Viral; Cell Line; Classical Swine Fever - pathology; Classical Swine Fever - transmission; Classical Swine Fever - virology; classical swine fever virus; Classical Swine Fever Virus - genetics; Classical Swine Fever Virus - immunology; Classical Swine Fever Virus - pathogenicity; Experimental infection; Fever; Genotype; Hog cholera; Hogs; Hyperthermia; Infarction; Infections; Inoculation; Japan; Outbreaks; Reverse Transcriptase Polymerase Chain Reaction - veterinary; RNA, Viral - analysis; RNA, Viral - blood; Spleen; Spleen - pathology; Sus scrofa; Swine; Virology; Virulence - genetics; Japan; classical swine fever virus; Japan; experimental infection
• ISSN: 0916-7250; 1347-7439; 1347-7439
• DOI: 10.1292/jvms.19-0133

Following an outbreak of classical swine fever (CSF) in Japan, 2018, CSFV JPN/1/2018 was isolated from an infected pig sample. In this study, we carried out a comparative experimental infection in pigs using this strain and the highly virulent ALD strain and compared outcomes, including clinical manifestation, virus shedding patterns and antibody responses. Although pigs inoculated orally or intramuscularly with JPN/1/2018 developed hyperthermia and had decreased leucocyte numbers, they survived for the whole experimental period and showed less severe clinical signs than those infected with the ALD strain. We confirmed the presence of characteristic multifocal infarction of the margin of the spleen that arises following infection with JPN/1/2018, albeit that this finding was not observed in all infected pigs. Both viruses efficiently spread to contact pigs in a similar manner, suggesting in transmissibility between the two strains. Viral RNAs were detected in all clinical samples, especially whole blood samples, before the pigs developed hyperthermia until at least approximately 2 weeks after inoculation. Our findings will be valuable for the investigations into epidemic events occurring in Japan and for establishing diagnostic strategies and control measures against CSF.