Independent evolution of porcine reproductive and respiratory syndrome virus 2 with genetic heterogeneity in antigenic regions of structural proteins in Korea

Genomic characteristics and pathogenicity of natural recombinant porcine reproductive and respiratory syndrome virus 2 harboring genes of a Korean field strain and VR-2332-like strain

“…However, the virus was actually a Korean field strain that recombined with a vaccine-like strain. This point highlights the importance of an advanced method to identify PRRSV strains using broader regions, for example entire structural genes (Kwon et al, 2018). In this study, mild-to-moderate respiratory clinical signs and an increase in rectal temperature were observed in challenged pigs.…”

“…Korean MN184-like strains are closely related to the MN184 strain and they share identical discontinuous nucleotide deletions within nsp2 (Choi et al, 2014). Korean MN184-like viruses account for a large proportion of PRRSV-2 in Korea and form a unique clade distinct from other MN184-like viruses identified in other countries (Kwon et al, 2018). Since the first commercialization of a PRRSV-2 vaccine in 1997, the use of a modified live vaccine (MLV) has become an important strategy to control PRRSV infection.…”

“…In Korea, PRRSV-2 was the only species of PRRSV until 2005, when PRRSV-1 was first identified in a commercial pig herd (Cha et al, 2006;Kim et al, 2006). Currently, both PRRSV-1 and PRRSV-2 co-circulate in Korean pig populations and cause huge economic losses to the swine industry (Kwon et al, , 2018Lee et al, 2017). Over the past two decades, Korean PRRSV-2 has expanded its genetic diversity through the continuous evolution and emergence of novel strains, which results in the independent evolution of the virus in Korea (Kwon et al, 2018).…”

“…Currently, both PRRSV-1 and PRRSV-2 co-circulate in Korean pig populations and cause huge economic losses to the swine industry (Kwon et al, , 2018Lee et al, 2017). Over the past two decades, Korean PRRSV-2 has expanded its genetic diversity through the continuous evolution and emergence of novel strains, which results in the independent evolution of the virus in Korea (Kwon et al, 2018). Specifically, some of Korean PRRSV-2 strains are phylogenetically related to MN184 strain as well as NADC30 strain, both of which were identified in United States in 2001 and 2008, respectively (Brockmeier et al, 2012;Han et al, 2006).…”

Peer Review #1 of "Evaluation of a type 2 modified live porcine reproductive and respiratory syndrome vaccine against heterologous challenge of a lineage 3 highly virulent isolate in pigs (v0.1)"

“…The type II viruses are further sub-classified into nine distinct lineages based on sequences of open reading frame 5 (ORF5) (Shi et al 2010). In Taiwan, PRRSVs predominantly belong to lineage 3 of type II and are circulating in almost all pig farms (Deng et al 2015;Kwon et al 2019;Lin et al 2019). In our previous study, some highly virulent lineage 3 strains were able to trigger considerable economical losses (30% mortality in the nursery phase) in the field and could induce severe clinical signs and high mortality in healthy experimental pigs (Hou et al 2019).…”