Summary
Pseudorabies virus (PRV), the cause agent of Aujeszky’s disease, is an infectious pathogen which greatly affects the heathy development of pig industry worldwide. The low specific host tropism of PRV allows this virus to infect a variety of animals, such as pigs, cattle, minks, dogs, and even possible humans. However, the occurrence of PRV natural infection in goats has never been documented. Herein we provided robust evidences demonstrating the first case of a variant PRV infection leading to the acute goat death in Yunnan Province, China, which might be resulted from mixed feeding with PRV-infected fattening pigs. Therefore, this report not only highlights the potential threat of newly emerging variant PRV strain(s) to goat industry, but also appeals the development of effective and safe vaccines against PRV variants for goats/ruminants in future.
Keywords: pseudorabies virus variant, goat, natural infection, China
Introduction
Pseudorabies virus (PRV), also called as Suid alphaherpesvirus 1 that belongs to the genus Varicellovirus of the sufamilyAlphaherpesviridae , within the family Herpesviridae , is an enveloped virus with a length of nearly 143 kb linear double-stranded DNA genome encoding more than 72 genes (Sun et al., 2016; Szpara et al., 2011). The unique natural and reservoir host for PRV are pigs (including wild boars), however the first suspected infection of this pathogen was recorded in American cattle with clinical signs characterized by intense itching in 1813 (Laval & Enquist, 2020). Since the initial isolation of PRV in 1902, the presence of this pathogen was widely documented almost in all pig raising countries, indicating that PRV has quickly swept across the world and posed a huge threat to various animal species, especially to the development of pig industry (Lee & Wilson, 1979).
Pseudorabies (PR) is a highly contagious disease that causes severe clinical symptoms in the infected pigs, thereby leading high morbidity and mortality especially to the sucking piglets. The infected piglets usually present clinical signs characterized by diarrhea, vomiting, nervous system disorders (such as tremor, dyskinesia, and lethargy) (Sun et al., 2016). Vaccination is regarded as the most effective approach for the eradication of PR. Though the infectious disease has successfully been eradicated in some developed countries via the wide application of virulent gene-deleted live vaccines, PRV remains a fatal pathogen circulating in Chinese pig population (Freuling, Müller, & Mettenleiter, 2017; Sun et al., 2018). In this regard, at least two great PR outbreaks have been witnessed in China, mainly resulting from PRV classical strains prevalent in the 1990s and variant strains circulating after 2011, respectively.
PRV has a broad species tropism, which facilitates it to infect a variety of mammals, including carnivores (Jin, Gao, Liu, Zhang, & Hu, 2016; H. Liu et al., 2017; Serena et al., 2018), ruminants (Cheng et al., 2020), and rodents. Even a case of human encephalitis caused by a PRV variant strain has been reported recently (Q. Liu et al., 2020). However, naturally occurring PRV infection in goats has not been reported yet. In current study, we provided the first case of a variant PRV infection causing the acute goat death in Yunnan province, China. Meanwhile, the genetic characteristics of this PRV strain YNG were characterized in detail.
Materials and methods