Jan 2026· Transboundary and Emerging Diseases· Vol 2026· 0 citations· 44 references
Medicine
TL;DR
It is demonstrated that the attenuated strain AHFY‐F140 represents a promising vaccine candidate against both NADC30‐like and JXA1‐like PRRSV infections.
Abstract
Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) is one of the major pathogens threatening the global swine industry and causes enormous economic losses annually. Vaccination remains one of the most important strategies for the prevention and control of PRRSV infection. In this study, a novel genotype 2 NADC30‐like PRRSV strain, designated AHFY, was isolated and characterized from eastern China. Phylogenetic analysis revealed that strain AHFY belonged to sublineage 1.8. An attenuated strain, AHFY‐F140, was obtained through 140 serial passages in MARC‐145 cells. Genomic sequence comparison between AHFY‐F140 and the parental strain AHFY‐F1 identified two discontinuous amino acid (aa) deletions in the nonstructural protein 2 (NSP2) gene, spanning residues 355–364 and 391–583, which were first detected at passage 90 and persisted through passage 140. The viral titer gradually increased with passaging, rising from 104.3 TCID50/mL for the parental strain AHFY‐F1 to 108.7 TCID50/mL for AHFY‐F140. A pathogenicity evaluation was conducted in 4‐week‐old PRRSV‐free New American Line piglets using AHFY‐F1 and AHFY‐F140. Piglets inoculated with AHFY‐F1 developed persistent fever and obvious respiratory clinical signs, accompanied by severe and typical histopathological lung lesions. In contrast, piglets inoculated with AHFY‐F140 showed no fever or other clinical signs. PRRSV‐specific antibodies became positive at 11 days postinoculation (dpi) in AHFY‐F140‐inoculated piglets, which was later than the 7 dpi observed in AHFY‐F1‐inoculated piglets. Furthermore, immunization with AHFY‐F140 provided robust protection against subsequent challenge with either the parental strain AHFY‐F1 or the highly pathogenic PRRSV (HP‐PRRSV) strain JXA1 (lineage 8). Collectively, these findings demonstrate that the attenuated strain AHFY‐F140 represents a promising vaccine candidate against both NADC30‐like and JXA1‐like PRRSV infections.
ABSTRACT The high genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant challenge to effective vaccination and infection prevention. Recently, NADC30-like PRRSV has become dominant in China. In this study, we characterized a PRRSV isolate XJ2020 from a vaccinated pig. The isolate exhibited moderate pathogenicity in piglets and clustered within the same sub-lineage as NADC30. Sequence analysis identified a unique deletion of the serine residue at position 32 (S32) in the GP5 protein. This deletion was introduced into a highly pathogenic PRRSV (HP-PRRSV) strain, JX2015, to generate the mutant JX2015-ΔS32 using a reverse genetic approach. We found that JX2015-△S32 showed reduced propagation in Marc-145 cells and decreased sensitivity to neutralization by MLV-derived anti-PRRSV positive serum, but exhibited enhance replication in primary porcine alveolar macrophages (PAMs) compared to its parental strain JX2015. Interestingly, the viral load in lung and ileum samples from JX2015-△S32-infected piglets was higher, but the lung injury was milder than in JX2015-infected piglets. Overall, this study highlights the S32 site in the PRRSV GP5 protein as an important factor influencing virus propagation, neutralization, cell tropism and pathogenicity in piglets, and suggests that targeting this residue could lead to the development of more effective PRRSV vaccines.
Xingdong Zhou, Xiaohui Zhang, E. Kan et al.· Virulence· 0 citations
ABSTRACT Porcine reproductive and respiratory syndrome virus (PRRSV) remains a major threat to the swine industry globally. In China, the dominance of PRRSV 2 is complicated by the emergence and co-circulation of genetically distinct strains, including a rising number of PRRSV 1 cases. In this study, the concurrent circulation of PRRSV 1 and PRRSV 2 was identified, and two novel strains AHB1 and Chah2022 were isolated from a single sow farm experiencing reproductive failure. Genetic analysis revealed that AHB1 shared 81.6%-83.6% nucleotide identity with subtype 1 strains of PRRSV 1 and clustered within a new evolutionary branch, characterized by a continuous 54-amino acid deletion in nsp2 and 1-amino acid deletion in the GP3-GP4 overlap region. In contrast, Chah2022 was identified as a recombinant virus with NADC30-like (lineage 1) and highly pathogenic PRRSV-like (lineage 8) strains. Pathogenicity assessment in nursery piglet model demonstrated that both AHB1 and Chah2022 had established systemic and persistent infections, although with low or moderate clinical signs. Our findings provide the evidence of PRRSV 1 and PRRSV 2 concurrent circulation in the single sow farm in China, which highlights the ongoing evolution of both Chinese PRRSV species and underscores the urgent need for enhanced surveillance and updated control strategies.
Zhendong Zhang, Di Gao, Zihe Wang et al.· Virulence· 0 citations
Brucellosis is one of the most severe Class B infectious diseases prevalent in the agricultural and pastoral areas of northern China. Current attenuated live vaccines (e.g., M5, S19) have defects such as residual virulence, causing abortion in pregnant animals, and the inability to differentiate between natural infection and vaccination (DIVA). Relying on the ABSL-3 laboratory of the Inner Mongolia Center for Disease Control and Prevention, this study established a chronic infection model in C57BL/6J mice using the virulent strain Brucella melitensis M16. Single-cell transcriptome sequencing (10x Genomics) was employed to map the heterogeneity of splenic immune cells. Whole-genome scanning and pangenomic analysis were performed on four strains with different virulence levels (M16, 544 A, M5, 104 M) using second-generation sequencing. Membrane/secreted proteins unique and conserved in virulent strains were screened as candidate antigens, prepared via prokaryotic expression systems, and their humoral and cellular immune levels were detected by indirect ELISA and flow cytometry. A stable chronic infection model was successfully constructed (bacterial load Log10 CFU > 4.5). Single-cell sequencing yielded 45,231 cells, annotated into 12 immune cell subpopulations, revealing significant expansion of Effector CD4 + T cells (P < 0.01) and high expression of the Ifng gene. Pangenomic analysis identified three candidate antigens (BMEI0021, BMEI1943, BMEI0367) that are 100% conserved in virulent strains but absent in the vaccine strain M5. Immunogenicity assays showed that BMEI1943 induced high levels of IgG2a subtype antibodies (titer Log2 13.45 ± 0.52) and IFN-γ + CD4 + T cell responses (frequency 15.80% ± 2.10%). Through multi-omics integration analysis, this study successfully identified a novel candidate antigen, BMEI1943, with strong Th1-type immunogenicity, providing an experimental basis for the development of safe and efficient subunit vaccines against brucellosis.
Zhiheng Dong, Sha Li, Jiarong Guo et al.· Brazilian Journal of Microbi...· 0 citations
Pseudorabies virus (PRV) and Porcine epidemic diarrhea virus (PEDV) are currently co-circulation among swine herd with multiple variant strains, which cause severe economic losses to the global swine industry. In the present study, a recombinant PRV-based vaccine candidate was constructed backbone of a PRV variant via deletion of five genes (gI, gE, US2, US9, and TK) and insertion of the S1 gene derived from a PEDV G2b strain, and the resulting recombinant virus was generated as rPRV-Δ5-S1. The safety of the quintuple-gene-deleted PRV vector (rPRV-Δ5) was firstly evaluated in rabbits and compared with the previously generated triple-gene-deleted vector (rPRV-Δ3). Rabbits inoculated with rPRV-Δ5 exhibited milder clinical manifestations, lower viral loads in tissues, and fewer histopathological lesions, indicating an improved safety profile. Subsequent immunization trials in mice demonstrated that rPRV-Δ5-S1 induced PEDV S1-specific antibodies and PEDV-neutralizing antibodies, which were higher than those observed in the commercial inactivated PEDV vaccine group. Furthermore, rPRV-Δ5-S1 elicited higher neutralizing antibody titers against PRV variants than the Bartha-K61 vaccine and provided complete protection against lethal challenge with the PRV variant. To further validate the immunogenicity and protective efficacy of rPRV-Δ5-S1, challenge experiments were conducted in piglets. The results showed that piglets immunized with rPRV-Δ5-S1 developed detectable antibody responses against both PRV and PEDV. After challenge with the PEDV G2b variant, rPRV-Δ5-S1-immunized piglets exhibited reduced diarrhea severity, decreased viral shedding, alleviated intestinal lesions, and improved weight gain compared with control animals. Collectively, these findings demonstrate that the quintuple-gene-deleted PRV vector exhibits an improved safety profile and can serve as an effective platform for heterologous antigen delivery. The recombinant virus rPRV-Δ5-S1 can induced immune responses against both PRV and PEDV in multiple animal models, which supports its potential as a bivalent vaccine candidate against these two economically critical swine pathogens.
Junda Li, Jiadeng Jiang, Ruhai Guo et al.· Frontiers in Microbiology· 0 citations
ABSTRACT African swine fever (ASF) is a highly contagious and lethal disease, but few therapeutic options are available for its treatment. Therefore, there is an urgent need for the development of safe and effective vaccines. In this regard, we described the differential effect of deletion of whole MGF100 and MGF300 families from genotype II highly virulent strains on African swine fever virus (ASFV) replication, virulence, and induction of protection. The resulting ASFV-Δ100 and ASFV-Δ300 mutants demonstrated reduced growth kinetics in vitro, with the former displaying aberrant virus morphogenesis. ASFV-Δ100 was efficiently attenuated, whereas ASFV-Δ300 retained its virulence. In the homologous lethal challenge, the two mutants achieved the same protection rate, with the former providing more protection against pathology in organs. Mechanistically, we found that ASFV-Δ100 was capable of inducing a robust innate immune response in vitro and a consistent P30 antibody response in vivo. In conclusion, the MGF100 family is a potential multigene-deleted target for ASFV live-attenuated vaccine development.
Wen Dang, Fan Xu, Yu Du et al.· Virulence· 0 citations
The findings suggest that internal gene backbone compatibility may influence vaccine immunogenicity and warrant further validation to support a refined vaccine design strategy for H7N9 and potentially other avian influenza subtypes.
Yi Liu, Meng-Yuan Bai, Tao Zhang et al.· Microorganisms· 0 citations
