Porcine circoviruses (PCVs), encompassing porcine circovirus type 1 (PCV1), porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), and porcine circovirus type 4 (PCV4), have been documented in China and represent a significant threat to the swine industry. Nevertheless, there is a paucity of data regarding the infection characteristics of PCVs across different age groups within intensive pig farming operations. In this investigation, a systematic cross-sectional methodology was employed to collect 415 testicular processing fluid samples and 1583 serum samples from 30 breeding farms and 27 fattening farms in China. All samples underwent analysis using real-time quantitative polymerase chain reaction (qPCR). Among the testicular fluid samples from suckling pigs, the detection rates for PCV1, PCV2, PCV3, and PCV4 were 56.9%, 31.1%, 75.4%, and 2.2%, respectively. The lowest mean cycle threshold (Ct) values for PCV1 and PCV3 were observed in testicular fluid as opposed to serum samples. At the individual level, the detection rate of PCV1 was significantly higher in fattening pigs (28.7%) and sows (28.7%) compared to nursery pigs (8.5%). The detection rate of PCV2 was highest in fattening pigs (43.1%) and lowest in sows (19.2%). The infection profile of PCV3 contrasted markedly with that of PCV2, exhibiting the lowest prevalence in fattening pigs (8.1%) and the highest in sows (46.1%). PCV4 was infrequently detected across all age groups, with prevalence rates ranging from 0% to 1.7%. Furthermore, the incidence of mixed infections involving the four PCV types was observed to be 12.7% in nursery pigs, 16.8% in fattening pigs, and 22.4% in sows. Notably, no strong correlation was identified between any two co-detected PCV types across all pig age categories. The findings of this study contribute valuable insights into the infection dynamics of PCVs across different pig age groups. Additionally, this research offers critical reference information for devising strategies to prevent PCV infections in intensive pig farming operations in China.

Avian influenza (AI) continues to threaten global poultry production, with accumulating evidence suggesting that certain commercial layer lines may exhibit increased susceptibility under specific experimental conditions compared with broiler chickens. This narrative review synthesizes published experimental infection studies identified through a comprehensive PubMed search, focusing on low pathogenic H9N2 and highly pathogenic H5N1, H5N2, H7N7, and H7N9 viruses. Although bird age and production stage varied across studies, consistent disparities in immune regulation and viral replication dynamics have been reported. We critically evaluate host determinants underlying these differences—including microRNAs, major histocompatibility complex polymorphisms, sialic acid receptor distribution, gut microbiota, and hormonal influences—and integrate findings across viral subtypes and pathogenicity classes to inform breed-tailored vaccination, nutritional, and therapeutic strategies.

Rotavirus is a leading cause of severe, dehydrating diarrhea in infants and young animals, causing significant global morbidity and mortality. For decades, research was hindered by challenges in establishing reverse genetics systems due to the virus’s complex segmented genome and poor cell culture adaptation. The first helper virus-dependent system (2006) was limited by low efficiency. A 2017 breakthrough established the first fully plasmid-based system, which eliminated helper viruses and revolutionized the field. Subsequent optimizations, such as codon modification and CRISPR/Cas9 integration, have significantly enhanced efficiency, enabling viable systems for diverse human and animal strains. This narrative review summarizes the evolution and technological milestones of rotavirus reverse genetics. We discuss critical applications in analyzing viral gene function, developing novel vaccines, screening antiviral drugs, and investigating cross-species transmission. Finally, we provide an outlook on the future prospects of this transformative technology.

Avian influenza virus (AIV), a zoonotic pathogen capable of cross-species transmission, poses a significant global health threat due to its rapid evolutionary adaptation. This review consolidates evidence from the past decade on AIV-autophagy interactions, emphasizing mechanistic insights and therapeutic potential. Research indicates that various AIV strains can trigger autophagosome formation via viral components, although the completeness of autophagic flux is not fully understood. These virus–host interactions are notably influenced by viral genotypes (e.g., H5N1 vs. H9N2) and host species (avian vs. mammalian). Current studies suggest that modulating autophagy may reduce AIV-induced acute lung injury, with pharmacological agents showing potential in mitigating inflammatory responses. We systematically explore three research areas: (1) strain-specific mechanisms of autophagy induction, (2) host-specific autophagic responses in poultry and human models, and (3) the therapeutic potential of stage-specific autophagy manipulation. This synthesis clarifies critical knowledge gaps, particularly the need for standardized autophagic flux assessment in avian cells, while providing a conceptual framework for developing autophagy-targeted strategies against AIV pathogenesis.