Recombination between NADC34‐like and QYYZ‐like strain of porcine reproductive and respiratory syndrome virus with high pathogenicity for piglets in China

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen that causes huge economic losses to the swine industry worldwide. Here, a novel variant of PRRSV strain named TJnh2021 was isolated from nursery piglets with morbidity rate (75%) and mortality rate (40%) in Tianjin Province of China in 2021. Phylogenetic and molecular evolutionary analyses revealed that TJnh2021 was highly similar to NADC34‐like (lineage 1.5, isolated in North America in 2014) in the ORF1ab‐ORF2 and ORF6‐ORF7 coding regions, as well as to QYYZ‐like (lineage 3, isolated in China in 2010) in the ORF3‐ORF5, suggestive of a natural recombination event. Recombination analyses revealed that recombination events occurred in two interlineage recombination events between lineages 1.5 and 3, and two breakpoints in ORF2 (nt12196) and ORF5 (nt13628) (with reference to the VR‐2332 strain). Animal experiments demonstrated that TJnh2021 caused mortality rates of 40% and exhibited higher pathogenicity in piglets compared to other lineage 1.5 strains reported in China. Taken altogether, NADC34‐like PRRSV has undergone genetic exchange with Chinese local PRRSV strains and recombination might be responsible for the variations in pathogenicity and highlight the importance of surveillance of this lineage in China.

Genome-Wide Characterization of QYYZ-Like PRRSV During 2018–2021

“…Moreover, the QYYZ-like strains (sublineage 3.5) were prevalent only in mainland China. According to the results of this study and previous studies, QYYZ-like strains have been occasionally reported in northern China ( 19 , 26 , 28 , 53 ) but are mainly prevalent in southern and central China ( 12 – 16 , 23 – 25 , 27 , 29 , 30 , 32 ). Although recombination of PRRSV is very common, many non-recombination strains of JXA1-like ( 54 ), VR2332-like ( 28 ) and NADC30-like/NADC34-like PRRSV ( 7 , 55 ) have been reported after long-term evolution in China.…”

Molecular Characteristics and Pathogenicity of a Novel Recombinant Porcine Reproductive and Respiratory Syndrome Virus Strain from NADC30-, NADC34-, and JXA1-Like Strains That Emerged in China

“…Previous studies have identified four lineages (lineages 1, 3, 5, and 8) of PRRSV-2 in China, and lineage 1 PRRSVs isolated from China were further classified into sublineage 1.5 (NADC34-like PRRSV) and sublineage 1.8 (NADC30-like PRRSV) ( 24 ). More importantly, NADC34-like PRRSV has undergone complex recombination with local Chinese strains ( 31 , 32 ). In China, the coexistence of different lineages of PRRSV in the field, coupled with the pressure of immunization, may aggravate the evolution of PRRSV, thereby increasing the difficulty of prevention and control of PRRS.…”

High Pathogenicity of a Chinese NADC34-like PRRSV on Pigs

“…Several Chinese NADC34-like PRRSVs reported before 2022 were found to have recombination with U.S. PRRSV strains including IA/2014/NADC34, ISU30, and NADC30 ( 2 ). Most recently, one Chinese NADC34-like PRRSV was found to have recombination with local PRRSV strain QYYZ, indicating the quick evolution of it to better adapt to domestic pigs ( 9 ). In addition to recombination events, patterns of aa deletions different from the 100-aa deletion in NSP2 were also observed, which make NADC34-like PRRSVs more complex in the field ( 2 ).…”

“…Song et al reported that HLJDZD32-1901, an NADC34-like PRRSV, was mildly pathogenic in piglets ( 6 ). In contrast, another Chinese NADC34-like PRRSV was reported to have high pathogenicity to pigs ( 9 ). In our previous study, we successfully isolated an NADC34-like PRRSV, designated JS2021NADC34, from a pig farm in Jiangsu province where sows suffered increased abortions and piglets had high mortality ( 8 ).…”