Since the rise of porcine reproductive and respiratory syndrome virus (PRRSV) in China, mutations have occurred regularly. In particular, the emergence of HP-PRRSV has significantly improved the pathogenicity of PRRSV. It has brought huge economic losses to the Chinese pig farming industry. To understand the current prevalence and evolution of PRRSV in Shandong Province, 1,344 samples suspected of having PRRSV were collected from local hog farms of different sizes. Genetic variation in the isolated PRRSV ORF5 gene was analyzed using the RT-PCR method. The results showed that the detection rate of PRRSV in the collected samples was 25.44%. The predominant strain of PRRSV in Shandong Province is still NADC30-like. However, it cannot be ignored that NADC34-like is also starting to become a prevalent strain. Mutations in ORF5 amino acids 13, 151 and neutralizing epitope (aa36-aa52) in some isolates can cause changes in virulence and ability to escape immunity. This study enriches the epidemiological data on PRRSV in Shandong Province, China. It provides an important reference for the development of new vaccines and for the prevention and control of PRRSV.

In recent years, the poultry industry had been markedly affected by adenoviral diseases such as hydropericardium syndrome and inclusion body hepatitis caused by fowl adenovirus (FAdV), which have become increasingly prevalent in China. Shandong Province, China, is an important area for poultry breeding where various complex and diverse FAdV serotypes were isolated. However, the dominant strains and their pathogenic characteristics are not yet reported. Therefore, a pathogenicity and epidemiological survey of FAdV was conducted, showing that the local dominant serotypes of FAdV epidemics were FAdV-2, FAdV-4, FAdV-8b, and FAdV-11. Their mortality rates in the 17-day-old specific-pathogen-free (SPF) chicks ranged from 10 to 80%; clinical signs included mental depression, diarrhea, and wasting. The maximum duration of viral shedding was 14 days. The highest incidence in all infected groups was on days 5–9, and then gradual regression occurred thereafter. The most pronounced symptoms occurred in chicks infected with FAdV-4, including pericardial effusion and inclusion body hepatitis lesions. Our results add to the current epidemiological data on FAdV in poultry flocks in Shandong and elucidate the pathogenicity of dominant serotypes. This information may be important for FAdV vaccine development and comprehensive epidemic prevention and control.

Chicken infectious anemia (CIA) is a vertical transmission infectious chicken disease caused by the chicken infectious anemia virus (CAV). The disease can induce stunting and immunosuppression in chicks by infecting bone marrow-derived stem cells, causing huge economic losses for the poultry industry. To determine the prevalence of CIA in Shandong Province, China, 854 suspected CIA samples were collected and analyzed in 13 cities in Shandong from 2020 to 2022. The PCR results showed that a total of 115 CAV were isolated. The CAV-positive rates were 17.21% (26/151) in 2020, 12.23% (35/286) in 2021, and 12.94% (54/417) in 2022, with severe mixed infections. Among them, CAV and fowl adenovirus (FAdV) were the most common, accounting for 40.86%. VP1 gene homology analysis showed that isolated strains shared 96.1–100% homology with the previously reported CAV strains. Genetic variation analysis showed that most of the isolated CAV strains were located in genotype A. These results indicate that CIA infection in Shandong chickens in recent years has been prevalent and mixed infections are common, but there were no significant genetic variations. Our results extend the understanding of the prevalence and genetic evolution of CIA in Shandong Province. They will offer new references for further study of the epidemiology and virus variation and the prevention and control of this disease.