Recombinant Bivalent Live Vectored Vaccine Against Classical Swine Fever and HP-PRRS Revealed Adequate Heterogeneous Protection Against NADC30-Like Strain

Abstract

The recombinant bivalent live vectored vaccine rPRRSV-E2 has been proved to be a favorable genetic engineering vaccine against classical swine fever (CSF) and highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS). NADC30-like strains have recently emerged in China and caused severe disease, and it is necessary to evaluate the vaccine candidate for the currently circulating viruses. This study established a good challenge model to evaluate the candidate rPRRSV-E2 vaccine in preventing infection with a representative NADC30-like strain (ZJqz21). It was shown that the challenge control piglets displayed clinical signs typical of PRRSV, including a persistent fever, dyspnea, moderate interstitial pneumonia, lymph node congestion, and viremia. In contrast, the rPRRSV-E2 vaccination significantly alleviated the clinical signs, yielded a high level of antibodies, provided adequate protection against challenge with ZJqz21, and inhibited viral shedding and the viral load in target tissues. Our results demonstrated that the recombinant bivalent live vectored vaccine strain rPRRSV-E2 can provide efficient protection against the challenge of heterologous circulating NADC30-like strain and could be a promising vaccine candidate for the swine industry.

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

“…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. All QYYZ-like strains were recombined with other lineages of PRRSV except the prototype strain QYYZ.…”

Lineage 1 Porcine Reproductive and Respiratory Syndrome Virus Attenuated Live Vaccine Provides Broad Cross-Protection against Homologous and Heterologous NADC30-Like Virus Challenge in Piglets

“…This PRRSV originated in the United States and has become one of the major endemic strains in China since 2016 [ 57 ]. The pathogenicity of NADC30-like PRRSVs ranges from moderate [ 26 , 36 , 38 ] to high [ 32 , 33 , 58 ], and most of them are moderately pathogenic [ 26 , 36 , 37 , 38 , 39 , 40 , 41 , 44 , 47 , 48 , 53 ]; however, the current commercial vaccines, Ingelvac PRRS MLV/RespPRRS MLV [ 44 , 52 ], CH-1a [ 47 ], HuN4-F112 [ 51 ], JXA1-P80 [ 52 ], R98 [ 53 ], TJM-F92 [ 51 ], and GDr180 [ 26 , 51 ], do not provide completely effective protection against NADC30-like PRRSVs. Here, we selected the moderately pathogenic NADC30-like PRRSV SD strain and described a newly developed lineage 1 PRRSV vaccine candidate, SD-R, which is efficacious in the prevention of clinical infection caused by NADC30-like PRRSVs.…”

“…Indeed, PRRSV vaccines have poor cross-protection effects [ 45 , 51 ]. Most studies have found that MLV cannot provide complete cross-protection in NADC30-like infected piglets, including shortening the period of fever with fewer pig numbers of clinical manifestations [ 37 , 44 , 47 , 51 , 52 , 53 ], only improving body weight gain at some point in the study [ 37 , 44 , 48 , 52 ], without decreasing the viremia or viral loads in tissues [ 51 , 64 ], and pathological lesions in lung and lymphoid tissues [ 37 , 47 , 51 , 52 ]; however, surprisingly, SD-R could provide better cross-protection (including no fever, a significant improvement in weight gain, a significantly reduced viral load in blood and tissues, and no visible pathological damage) ( Table S2 ), even though the genomic nucleotide similarity of SD and HLJWK108-1711 was only 89.9%. All the piglets immunized with SD-R and then challenged with SD or HLJWK108-1711 survived without any major clinical signs at any point in the experimental period.…”

“…In China, there are currently two types of PRRS vaccines: MLV and killed virus (KV) vaccines [ 47 ]. Nine commercial vaccines are currently used to control and prevent PRRSV infection in China, including Ingelvac PRRS MLV/RespPRRS MLV, CH-1R, HuN4-F112, JXA1-P80, R98, TJM-F92, GDr180, PC, and CH-1a (KV) [ 48 ]. Of these, RespPRRS MLV and R98 are of lineage 5, and the others belong to lineage 8 [ 47 ].…”

Genomic similarity and antibody-dependent enhancement of immune serum potentially affect the protective efficacy of commercial MLV vaccines against NADC30-like PRRSV

“…Since 2013, the NADC30-like PRRSV that likely originated from the NADC30 PRRSV strain circulating in North America around 2008, has been isolated and widely spread in China ( Zhao et al., 2015 ; Zhou et al., 2015 ; Wang et al., 2017 ). Although the pathogenicity of NADC30-like PRRSV is lower than that of HP-PRRSV, NADC30-like PRRSV has high variability and is prone to recombination with other PRRSV to form new PRRSV strains with complex genetic backgrounds and genomic characteristics ( Zhang et al., 2016 ; Zhou et al., 2018 ; Chen P. et al, 2021 ; Guo et al., 2021 ; Li Y. et al., 2021 ). Currently, NADC30-like PRRSV and HP-PRRSV are the dominant strains in China ( Li et al., 2016 ; Guo et al., 2019 ; Li L. et al, 2021 ; Zhang et al., 2022 ).…”