Evaluation of infectivity, virulence and transmission of FDMV field strains of serotypes O and A isolated in 2010 from outbreaks in the Republic of Korea

Authors: Pacheco Tobin, Juan; LEE, KWANG-NYEONG - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); Bishop, Elizabeth; Hartwig, Ethan; Pauszek, Steven; Smoliga, George; KIM, SU-MI - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); PARK, JONG-HYEON - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); KO, YOUNG-JOON - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); LEE, HYANG-SIM - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); DONGSEOB, TARK - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); CHO, IN-SOO - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); KIM, BYOUNGHAN - Animal, Plant And Fisheries Quarantine And Inspection Agency (QIA); Rodriguez, Luis; Arzt, Jonathan

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2015
Publication Date: 1/6/2016
Citation: Pacheco Tobin, J., Lee, K., Bishop, E.A., Hartwig, E.J., Pauszek, S.J., Smoliga, G.R., Kim, S., Park, J., Ko, Y., Lee, H., Dongseob, T., Cho, I., Kim, B., Rodriguez, L.L., Arzt, J. 2016. Evaluation of infectivity, virulence and transmission of FDMV field strains of serotypes O and A isolated in 2010 from outbreaks in the Republic of Korea. PLoS One. 11(1): e0146445. doi: 10.1371/journal.pone.0146445.

Interpretive Summary: Foot-and-mouth disease (FMD) is a highly contagious viral disease of cattle, pigs, sheep, goats, and wild cloven-hoofed animals. The disease is characterized by fever and blisters in the mouth, tongue, feet, and teats. FMD is one of the most economically significant diseases of animals based upon extreme losses that occur in association with outbreaks; impact from outbreaks includes massive depopulations of animals, decreased production, and international trade restrictions. Since the early 2000s, outbreaks of FMD have been described in several previously FMD-free Asian nations, including the Republic of Korea. One of the outbreaks was caused by a virus strain named FMD virus (FMDV) O/KOR/2010 that affected ruminants and pigs. In contrast, another virus strain, named FMDV A/KOR/2010, affected only ruminants. Based on these findings, the intention of the work described in the current report was to characterize and compare both strains under laboratory conditions in cattle and pigs, and correlate the findings with reports from the field outbreaks. In the current study, FMDV O/KOR/2010 was highly infectious in both species as seen in the field, whereas FMDV A/KOR/2010 affected mainly pigs but was less efficient in cattle, contrasting field reports. In conclusion, these data suggest that the less severe disease pattern found in cattle is more likely to be the cause of the limited spread of A/KOR/2010 rather than a lack of ability of this virus to infect pigs.

Technical Abstract: Since the early 2000s outbreaks of foot-and-mouth disease (FMD) have been described in several previously FMD-free Asian nations, including the Republic of Korea (ROK). One outbreak with FMD virus (FDMV) serotype A and two with serotype O occurred in ROK in 2010/2011. The causative viruses belong to lineages that had been spreading in East Asia since 2009 and continue to threaten countries in that region. Most FMDV strains have a broad host range, as occurred during the outbreaks of FMDV serotype O in ROK that affected ruminants and pigs. Contrastingly, the strain of serotype A affected only ruminants. Based upon these epidemiological findings, the intention of the work described in the current report was to characterize and compare the infectivity, virulence and transmission of both strains under laboratory conditions in cattle and pigs, by direct inoculation and contact exposure. As expected, FMDV serotype O was highly virulent in both cattle and swine by contact exposure and direct inoculation. Surprisingly, FMDV serotype A was highly virulent in swine, but was less infectious in cattle by contact exposure to infected swine or cattle. Interestingly, similar quantities of aerosolized FMDV RNA were detected during experiments with viruses of serotypes O and A. These data suggest that specific virus-host interactions of A/KOR/2010 affect the transmission of this strain to cattle, and this may explain, in part, the limited spread of the serotype A epizootic.