Effect of Porcine Epidemic Diarrhea Virus Infectious Doses on Infection Outcomes in Naïve Conventional Neonatal and Weaned Pigs

Thomas, Joseph T.; Chen, Qi; Gauger, Phillip C.; Giménez-Lirola, Luis G.; Sinha, Avanti; Harmon, Karen M.; Madson, Darin M.; Burrough, Eric R.; Magstadt, Drew R.; Salzbrenner, Holly M.; Welch, Michael W.; Yoon, Kyoung-Jin; Zimmerman, Jeffrey J.; Zhang, Jianqiang

Porcine epidemic diarrhea virus (PEDV), the causative agent of porcine epidemic diarrhea (PED), is an enveloped positive-sense, single-stranded RNA virus belonging to the order Nidovirale, family Coronaviridae, subfamily Coronavirinae, genus Alphacoronavirus [1] . PEDV was identified in 1978 [2, 3] although the disease was first recognized in England in 1971 [4] . PEDV caused widespread epidemics in several European countries during the 1970s and 1980s [5, 6] ; however, since the 1990s PED has become rare in Europe with occasional outbreaks [7] . PED was first reported in Japan in 1982 and has since been confirmed in other Asian countries such as South Korea, China, Thailand, and Vietnam [5, 8, 9] . PEDV was detected in the United States (U.S.) for the first time in April 2013 [10] . So far, at least two genetically different PEDV strains have been identified in the U.S. (U.S. PEDV prototype strain and S-INDEL-variant strain) [11, 12] . After the PED outbreak in the U.S., detection of U.S. prototype-like PEDV has been reported in Canada, Mexico, Taiwan, and South Korea [11, [13] [14] [15] ; detection of U.S. S-INDEL-variant-like PEDV has been reported in South Korea, Germany, Belgium and France [16] [17] [18] [19] [20] .