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Recent advances in the study of NADC34-like porcine reproductive and respiratory syndrome virus in China.

ABSTRACT: Since porcine reproductive and respiratory syndrome virus (PRRSV) was first described in China in 1996, several genetically distinct strains of PRRSV have emerged with varying pathogenicity and severity, thereby making the prevention and control of PRRS more difficult in China and worldwide. Between 2017 and 2021, the detection rate of NADC34-like strain in China increased. To date, NADC34-like strains have spread to 10 Chinese provinces and have thus developed different degrees of pathogenicity and mortality. In this review, we summarize the history of NADC34-like strains in China and clarify the prevalence, genomic characteristics, restriction fragment length polymorphisms, recombination, pathogenicity, and vaccine status of this strain in China. In so doing, this study aims to provide a basis for the further development of prevention and control measures targeting the NADC34-like strain.

SUBMITTER: Zhao HZ

PROVIDER: S-EPMC9354828 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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Recent advances in the study of NADC34-like porcine reproductive and respiratory syndrome virus in China.

Zhao Hong-Zhe HZ Wang Feng-Xue FX Han Xiao-Yu XY Guo Hao H Liu Chun-Yu CY Hou Li-Na LN Wang Ya-Xin YX Zheng Hui H Wang Lu L Wen Yong-Jun YJ

Frontiers in microbiology 20220722

Since porcine reproductive and respiratory syndrome virus (PRRSV) was first described in China in 1996, several genetically distinct strains of PRRSV have emerged with varying pathogenicity and severity, thereby making the prevention and control of PRRS more difficult in China and worldwide. Between 2017 and 2021, the detection rate of NADC34-like strain in China increased. To date, NADC34-like strains have spread to 10 Chinese provinces and have thus developed different degrees of pathogenicity ...[more]

PMID: 35935186

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Project description:In China, the porcine reproductive and respiratory syndrome virus (PRRSV) has undergone several variations over the decades and contributed to the diversity of the clinical epidemic PRRSV strains. This has complicated the prevention and control of PRRS. In particular, the efficacy of the currently available commercial vaccines against the highly pathogenic NADC34-like strains is unclear. Therefore, the objective of this study was to evaluate the protection efficacy of three commercial PRRS modified-live virus (MLV) vaccines derived from classical PRRS VR2332 MLV and R98 MLV against challenge with a heterologous NADC34-like PRRSV strain, JS2021NADC34, which has high pathogenicity in pigs. PRRSV- and antibody-free piglets were immunized with the PRRS VR2332 MLV vaccine or either of two R98 MLV vaccines (from different manufacturers) and were challenged with the JS2021NADC34 strain 28 days after immunization. Rectal temperature, clinical symptoms, viremia and viral shedding from the nose, gross lesions in the thymus and lungs, microscopic lesions and viral distribution in the lungs, as well as the humoral immune response and mortality rates were recorded over a 14-day post-challenge period. The results showed that PRRS VR2332 MLV had better efficacy against the JS2021NADC34 challenge than PRRS R98 MLV, with vaccinated piglets in the former group showing transient and mild symptoms, mild pathological lesions in the lungs, mild thymic atrophy, and low viral levels in sera and nasal swabs, as well as better growth performance and a 100% survival rate. In contrast, two PRRS R98 MLVs exhibited limited efficacy against the JS2021NADC34 challenge, with the piglets in two R98 groups showing obvious clinical symptoms and pathological changes in the lungs and thymus; moreover, there were two deaths caused by PRRS in two R98 groups, respectively. Despite this, the mortality rate was lower than that of the unvaccinated piglets that were challenged with JS2021NADC34. The cumulative results demonstrate that PRRS VR2332 MLV was partly effective against the highly pathogenic PRRSV NADC34-like strain based on the observations over the 14-day post-challenge period. Thus, it might be a viable option among the commercially available vaccines for control of NADC34-like virus infections in swine herds.

Project description:Recently, the emergence of a NADC34-like porcine reproductive and respiratory syndrome virus (PRRSV), which causes a large number of abortions in swine herds, has raised great concern in China. In this study, a PRRSV variant strain, PRRSV/CN/FJGD01/2021, evolved from recombination between NADC30-like, NADC34-like, and JXA1-like viruses was isolated in Fujian province in 2021, and its pathogenicity in piglets was examined. Animal experiments demonstrated that PRRSV/CN/FJGD01/2021 infection could induce 100% morbidity and cause higher viremia, a persistently higher fever (>40°C for 14 consecutive days), significant weight loss, and severe histopathological lung lesions compared to the NADC30-like FJZ03 strain and NADC34-like FJ0908 strain in piglets. The PRRSV/CN/FJGD01/2021 strain displayed higher pathogenicity than the FJZ03 and FJ0908 strains, but lower pathogenicity than the Chinese highly pathogenic (HP)-PRRSVs in piglets. Moreover, the Ingelvac PRRS modified live vaccine (MLV) provides incomplete cross-protection against heterologous PRRSV/CN/FJGD01/2021 in piglets. Our findings contribute to the understanding of the current epidemic situation of NADC34-like PRRSV in China. IMPORTANCE The pathogenicity of NADC34-like PRRSV has broad variations in virulence. Importantly, NADC34-like PRRSV has undergone complex recombination with local strains since it first emerged in 2017 in China. However, the pathogenicity of the recombinant NADC34-like virus was rarely experimentally evaluated in pigs. In this study, a novel PRRSV strain, PRRSV/CN/FJGD01/2021, was isolated from sows enduring a high-abortion-rate (20%) period in China in 2021. Notably, phylogenetic and recombination analyses revealed that PRRSV/CN/FJGD01/2021 is a recombinant virus from NADC30-, NADC34-, and JXA1-like isolates. PRRSV/CN/FJGD01/2021 was shown to cause higher virus load, persistent fever, significant weight loss, moderate respiratory clinical signs, and severe histopathological lung lesions in piglets. PRRSV/CN/FJGD01/2021 exhibited higher pathogenicity than NADC30-like FJZ03 and NADC34-like FJ0908, but lower than Chinese HP-PRRSVs for piglets. These data indicated that PRRSV/CN/FJGD01/2021 has intermediate virulence for piglets. Furthermore, the Ingelvac PRRS MLV could partly provide protective efficacy against PRRSV/CN/FJGD01/2021 challenge in piglets.

Project description:Since its recent appearance in China, the NADC30-like strains of porcine reproductive and respiratory syndrome virus 2 (PRRSV-2) have caused an expanding epidemic, and this has further expanded the genetic diversity of PRRSV. In this study, three NADC30-like strains-GXFCG20210401, GXQZ20210403 and GXNN20210506-were isolated from pig serum samples obtained in Guangxi, and their genomes were sequenced. A comparative analysis of the whole genomes showed that the three strains were most similar to NADC30 (88.3-88.7%). In particular, the non-structural protein coding regions (nsp1, nsp4-5, nsp7-8 and nsp9) showed the highest similarities to JXA1, and the ORF2a-ORF5 regions showed the highest similarities to NADC34. The three strains had same discontinuous deletions of 111+1+19 amino acids in the nsp2 region, which were similar to the NADC30-like strains. Phylogenetic tree analysis based on the ORF5 gene showed that the three PRRSV isolates were divided into lineage 1.5 along with the representative NADC34-like strains, but they were classified as NADC30-like strains with respect to the whole genome and nsp2 evolutionary trees. Recombinant analysis revealed complex recombination patterns in the genomes of the three strains, which likely originated from multiple recombination events among JXA1-like, NADC30-like and NADC34-like strains. The results from animal experiments showed that the GXQZ20210403 strain was 20% lethal to piglets and caused more severe clinical reactions than GXFCG20210401, and both recombinant strains were similar in terms of pathogenicity to the previously reported NADC34 strains. This study demonstrates that NADC34-like strains of PRRSV have been circulating in the southern provinces of China and have exchanged genomes with several other indigenous strains. In addition, differences in recombination patterns may cause different clinical pathogenicity and indicate the importance of the surveillance and preventive control of recombinant strains.

Dataset Information

Recent advances in the study of NADC34-like porcine reproductive and respiratory syndrome virus in China.

Publications

Recent advances in the study of NADC34-like porcine reproductive and respiratory syndrome virus in China.

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