The widely used pseudorabies virus (PRV) Bartha-K61 vaccine has played a key role in the eradication of PRV. Since late 2011, however, a disease characterized by neurologic symptoms and a high number of deaths among newborn piglets has occurred among Bartha-K61–vaccinated pigs on many farms in China. Clinical samples from pigs on 15 farms in 6 provinces were examined. The PRV gE gene was detectable by PCR in all samples, and sequence analysis of the gE gene showed that all isolates belonged to a relatively independent cluster and contained 2 amino acid insertions. A PRV (named HeN1) was isolated and caused transitional fever in pigs. In protection assays, Bartha-K61 vaccine provided 100% protection against lethal challenge with SC (a classical PRV) but only 50% protection against 4 challenges with strain HeN1. The findings suggest that Bartha-K61 vaccine does not provide effective protection against PRV HeN1 infection.
Tong-Qing An, Jin-Mei Peng, Zhi-Jun Tian, Hong-Yuan Zhao, Na Li, Yi-Min Liu, Jia-Zeng Chen, Chao-Liang Leng, Yan Sun, Dan Chang, and Guang-Zhi Tong; Pseudorabies Virus Variant in Bartha-K61–Vaccinated Pigs, China, 2012; Emerg Infect Dis [Internet]. 2013 Nov [date cited]. http://dx.doi.org/10.3201/eid1911.130177