Molecular Epidemiology and Pathogenic Characterization of Novel Chicken Infectious Anemia Viruses in Henan Province of China

Abstract

Chicken infectious anemia (CIA) is an immunosuppressive disease caused by the chicken infectious anemia virus (CIAV) resulting in heavy economic losses once an outbreak is established. This study conducted a systematic analysis of the epidemiology and pathology of CIA in Henan province, China. A total of 437 clinical tissue samples and 120 poultry disease-related live attenuated vaccines were collected during 2017–2020; of which 45 were positive for CIAV nucleic acid, with a positive rate of 8.08%. Our results showed that genome sequence similarity among a total of 12 CIAV isolates was high, and ranged from 97.1 to 99.3%, and their similarity to the vaccine strains Cux-1 and Del-Ros ranged from 97.8 to 98.6%. However, There were mutations in the locus of the major capsid proteins VP1, VP2, and VP3 among all isolates. The subsequent sequence analysis indicated that the isolates of HN-4 and HN-8 showed genetic recombination and follow up animal experiments revealed that HN-4 might be a pathogenic strain. Our results reveal that both field infection and non-CIAV vaccines contamination promote the epidemiology of CIAV in China and some dominant epidemic viruses have undergone recombination and evolution. This study provides important information to help with the prevention and control of CIAV in the poultry industry.

Retrospective Investigation and Genetic Variation Analysis of Chicken Infectious Anemia in Shandong Province, 2020–2022

“…Notably, the samples were from suspected CAV infections in their study. However, the positive rates of CAV in our study are closer to the 9.4% and 17.14% detection rates discovered during epidemiological surveillance of CIA in Guangxi and Henan Provinces [13,14]. In any case, the results indicate that CIA has been prevalent in Shandong Province in recent years.…”

“…CIA is not a highly lethal avian disease. However, when CAV infects chickens, it suppresses their immunity and leads to vaccine failure and secondary infections, so it is extremely important to investigate CAV prevalence [9,13]. In our study, the total detection rate of CAV in 2020-2022 was 13.46%.…”

“…Mixed infections of CAV and other viruses were also found in other parts of China. For example, mixed infections of CAV and ALV were found in Guangdong with a 17.5% positive rate, and the positive rate of CAV and FAdV was 26.6% in Guangxi [13,16]. This suggests that mixed infections of CAV are common in China.…”

“…Hence, only representative samples in 2021 and 2022 were chosen for sequencing the VP1 gene. Because the VP1 protein has the highest mutation rate, and mutations at certain key amino acid sites can also change the abilities of replication and transmission [13,17], the analysis of key amino acid sites in VP1 proteins was studied. The amino acid substitution patterns of VP1 protein at sites 75, 97, 125, 139, 141, 144, 157, 287, 290, and 294 are shown in Table 1.…”

“…In our study, most sequenced CAV isolates were in genotype A, consisting mainly of Asian indigenous strains (14/15). Only SDHY-220519 belongs to the exotic endemic strain consisting of genotype B, suggesting that the spread and inheritance of CAV may have a certain regional characteristic [13,18]. It is noteworthy that this genotype consists mainly of foreign strains, including vaccine strains AF313470 and M81223.…”