PATHOGENIC CHARACTERISTICS OF THE KOREAN 2002 ISOLATE OF FOOT-AND-MOUTH DISEASE VIRUS SEROTYPE O IN PIGS AND CATTLE

Authors: OEM, JAE-KU - MINS. OF AGRI., KOREA; YEH, MIN-TSUNG - USDA-APHIS-FADDL; MCKENNA, THOMAS - USDA-APHIS-FADDL; HAYES, JEFFREY - USDA-APHIS-FADDL; Rieder, Aida - Elizabeth; GIUFFRE, ANGELICA - USDA-APHIS-FADDL; ROBIDA, JOHN - USDA-APHIS-FADDL; LEE, K.N. - MINS. OF AGRI., KOREA; CHO, I.S. - MINS. OF AGRI., KOREA; FANG, X. - AMBION, INC.; JOO, Y.S. - MINS. OF AGRI., KOREA; PARK, J.H. - MINS. OF AGRI., KOREA

Submitted to: Journal of Comparative Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2008
Publication Date: 1/7/2008
Citation: Oem, J., Yeh, M., Mckenna, T., Hayes, J.R., Rieder, A.E., Giuffre, A.C., Robida, J.M., Lee, K., Cho, I., Fang, X., Joo, Y., Park, J. 2008. Pathogenic Characteristics of the Korean 2002 Isolate of Foot-and-Mouth Disease Virus Serotype O in Pigs and Cattle. Journal of Comparative Pathology. 138(4):204-214.

Interpretive Summary: Foot-and-mouth disease virus (FMDV), a member of the Aphthovirus genus within the Picornaviridae, is the causative agent of an economically important disease of cloven-hoofed animals, and the single most important constraint to trade in live animals and animal products. FMDV is a positive-stranded RNA virus of about 8.5 Kb that occurs as seven distinct serotypes (A,O,C,SAT1,SAT2,SAT3 and Asia 1). The Pan-Asia type O topotype has caused great devastation in Asia in recent years. The Republic of Korea had been free from foot-and-mouth disease (FMD) since 1934 until FMD outbreaks were reported in 2000. The outbreaks of FMD were contained and South Korea was free of the disease until 2002. This outbreak was a blow to South Korea's livestock and feed industries, which had recently resumed pork for the first time since the cattle outbreak in 2000 which had halted the pork shipments. This study describes the characteristics of FMDV O/SKR/AS/2002 and its pathogenicity for bovine and swine to better understand the outbreaks caused by this virus. It also provides information for epidemiologists to measure risk assessment and reduce the transmission of FMDV is a benefit of disease control.

Technical Abstract: Experimental infection of susceptible cattle and pigs with foot-and-mouth disease virus (FMDV) O/SKN/AS/2002 pig strain indicates that this virus causes a disease that is highly virulent and contagious in swine, but causes a very limited infection in bovine. Pigs directly inoculated with, or exposed to swine infected with, O/SKN/AS2002 pig strain demonstrated typical FMD clinical signs, including gross vesicular lesions in mouth and pedal sites. In addition, FMDV was isolated from; and FMDV genomic RNA was detected by real-time reverse transcriptase polymerase chain reaction (rRT-PCR) from; flood, serum, nasal swabs, and esophageal-pharyngeal (OP) fluid early in the course of infection. Antibodies against nonstructural protein (NSP) 3ABC, were detected in both directly inoculated and contact pigs, indicating that cative virus replication occurred in these animals. In contrast, the disease in cattle was atypical, with no lesions seen beyond those at the site of experimental inoculation. A transient viremia, at days one and two post inoculation (DPI) was present in the experimentally inoculated bovine, followed by the production of antibodies to NSP 3ABC, indicating a subclincial infection was present. No clinical disease was seen, and no antibodies to NSP 3ABC were detected in any contact bovines. Additionally, no virus was isolated and no viral nucleic acids were detected in blood, nasal swab, and OP fluid samples from the contact bovines. This experiment provides evidence that the virus was not transmitted from infected cattle to contact cattle. The virulence of O/SKN/AS/2002 in pigs and its avirulence in bovines resembles the porcinophilic strain of Cathay origin, FMDV O/TAW/97. O/TAW/97 has reduced ability to grow in bovine-derived cells;however,O/SKN/AS/2002 grew in bovine-derived cells in our experiment. The porcinophilic characteristic of FMDV O/TAW/97 has been attributed to a deletion in the 3A coding region of the viral genome. O/SKN/AS/2002 has an intact 3A coding region. Thus, at this time, we cannot correlate the porcinophilic phenotype of O/SKN/AS/2002 with a particular genetic marker.