Research Note: Molecular relationship of the fowl adenovirus serotype 4 isolated from the contaminated live vaccine and wild strains isolated in China, 2013-2018

Abstract

Since June 2013, hydropericardium-hepatitis syndrome caused by putative novel fowl adenovirus 4 ( FAdV-4 ) infection has spread all over China, leading to great economic losses. Previous study found that the use of attenuated vaccines contaminated with FAdV-4 is likely to be an important cause of such large-scale transmission. Here, we sequenced the whole genome of this strain through the next-generation sequencing and carried out a retrospective analysis of the FAdV-4 strains that have been determined in China recently. Results show the vaccine strain was almost 100% identical with wild virus strains, especially with 4 strains considering the difference of the GA repeat region, further linking the relationship between vaccine contamination and FAdV-4 prevalence in China. Meanwhile, there is no time and regional preference for the emergence of FAdV-4 strains with different molecular characteristics in China, which indicates that there may be multiple routes of transmission of this virus, suggesting that we still need to pay more attention to and formulate correct prevention and control in the future.

Genomic characteristics of a chicken infectious anemia virus strain isolated from contaminated chicken pox attenuated vaccine

“…Over the past two decades, many live vaccines have been proved to be contaminated with exogenous viruses, including avian leukosis virus (Mao et al, 2020), fowl adenovirus (Su et al, 2020), reticuloendotheliosis virus (Li et al, 2015), CIAV and others. This phenomenon is mainly caused by the use of SPF chicken embryos infected with exogenous viruses (Li et al, 2016).…”

Source Tracking of Chicken Infectious Anemia Virus in a SPF Chicken Population, the Latest Report in China

“…In general, the contamination of attenuated vaccines was mainly caused by the use of CIAV-positive SPF chicken embryos during propagation of seed virus [30]. Although strict surveillance for the vaccine contamination had been taken, several cases of exogenous virus contamination in live poultry vaccine had been reported, such as avian leukosis virus (ALV) [31][32][33], reticuloendotheliosis virus (REV) [34][35][36], and fowl adenovirus (FAdV) [37,38]. Therefore, it was of great signi cance to ensure the purity of SPF chicken embryos for vaccine manufacture.…”

Emergence of fowl aviadenovirus C-4 in a backyard chicken flock in California

“…The FAdV C-4 strain isolated here lies in a cluster of Chinese strains that are 99.99% identical, differing in only 6 bp in the genome, and with no amino acid changes: F-Vac, JSJ13, NIVD2, HLJFAd15, and ZJ2015. 17 Of these, F-Vac is the strain isolated from a contaminated Newcastle disease (Avian orthoavulavirus 1) viral vaccine; the remainder are wild strains isolated from the outbreaks in China. 17 The role of contaminated attenuated live Newcastle disease viral vaccines has been documented, and these vaccines are the suggested cause of the rapid and geographically distinct spread of FAdV outbreaks in China.…”

“…17 Of these, F-Vac is the strain isolated from a contaminated Newcastle disease (Avian orthoavulavirus 1) viral vaccine; the remainder are wild strains isolated from the outbreaks in China. 17 The role of contaminated attenuated live Newcastle disease viral vaccines has been documented, and these vaccines are the suggested cause of the rapid and geographically distinct spread of FAdV outbreaks in China. 15 The spread of the outbreaks was exacerbated mostly by contamination by both FAdV and CAV.…”