Genotype VII Newcastle disease virus (NDV) has been confirmed as the predominant epidemic strain in China. Traditional vaccine strains fail to provide complete immune protection when challenged with an epidemic strain. NDV vaccines with phylogenetic relationships closer to those of the endemic viruses demonstrate improved protective efficacy in reducing viral shedding and transmission. This research seeks to develop attenuated vaccine strains that are specifically aligned with NDV genotype VII. A reverse genetics system for the genotype VII NDV HB strain was developed, successfully rescuing the attenuated recombinant virus aHB by substituting the fusion protein (F) cleavage site motif “¹¹²R-R-Q-K-R↓F¹¹⁷” with “¹¹²G-R-Q-G-R↓L¹¹⁷.” Recombinant aHB virus attenuation was verified by assessing the mean death time (MDT) and intracerebral pathogenicity index (ICPI). The attenuated aHB strain demonstrated greater proliferation titers than did the virulent HB and rHB strains both in vivo and in vitro. Furthermore, the genome exhibited significant genetic stability even after 10 passages in chicken embryos. When challenged with the HB strain of NDV genotype VII, the aHB-inactivated vaccine provided 100% protection to chickens and effectively prevented viral shedding. These findings indicate that recombinant aHB may serve as an effective vaccine candidate.

Pigeon paramyxovirus type 1 (PPMV-1) poses a significant threat to pigeon farming in China, and understanding its biological characteristics and pathogenicity is critical for vaccine development and disease control. In this study, we characterized a PPMV-1 QY strain, performed full-length genome sequencing, and constructed a phylogenetic tree based on the F gene. Then, the biological properties and the pathogenicity of the QY strain were assessed and evaluated in vitro and in vivo. The results showed that phylogenetic analysis classified the QY strain within subgenotype VI.2.1.1.2.2, the predominant circulating strain in China. The QY strain exhibited a 50% egg infectious dose (EID₅₀) of 10^−6.8/0.1 mL, mean death time (MDT) in chicken embryos of 68.7 ± 2.1 h, and intracerebral pathogenicity index (ICPI) in one-day-old chicks of 1.12, which indicate it is a moderately virulent strain. Animal experiments showed that the QY strain resulted in a mortality rate of 66.7% in healthy pigeons. Necropsy findings included cerebral congestion and swelling, hemorrhagic glandular stomach papillae, tracheal ring hemorrhages, and duodenal congestion and swelling. Histopathological analysis revealed extensive inflammatory infiltration in the lungs and liver, widespread intestinal erosion, and severe necrosis of splenic red pulp cells. In conclusion, the QY strain belongs to subgenotype VI.2.1.1.2.2 and exhibits moderate virulence, causing high mortality and severe pathological lesions in infected pigeons. These findings provide valuable insights into the pathogenicity of PPMV-1 and the specific mutations in the F protein can serve as potential attenuation targets in vaccine development against the emerging subgenotype VI.2.1.1.2.2.

In 2025, an infectious bronchitis virus (IBV) strain of the GVIII genotype was identified and isolated from a poultry farm in Hebei Province, China, representing the first documented detection of this IBV genotype within the country to date. Nucleotide homology analysis revealed that the S1 gene of this isolate shares 62.2%–96.9% sequence identity with previously reported GVIII‐type strains from other countries. Comprehensive phylogenetic analysis of the complete genome indicated that this strain originated from a single recombination event: Its S gene may have been derived from the GVIII‐1 lineage strain IBV/Ck/USA/CA/21‐1883, while the remaining genomic regions were likely acquired from the GI‐19 lineage strain SD. Pathogenicity evaluation demonstrated that infected flocks exhibited reduced body weight gain, with 40% of chickens showing signs of diarrhea. Necropsy findings included hemorrhagic lesions at the proventriculus‐gizzard junction and within the bursa of Fabricius. Moreover, 85% of infected hens developed severe oviduct hypoplasia, and 90% showed a reduction in follicular number. The isolate described in this study constitutes the first detection of a GVIII genotype IBV strain in China, although its route of introduction remains undetermined. The emergence of this strain highlights the necessity for sustained molecular surveillance of IBV and the development of genotype‐matched vaccines.