Detection of reticuloendotheliosis virus as a contaminant of fowl pox vaccines

Abstract

This study was designed to detect reticuloendotheliosis virus (REV) as a contaminant in fowl pox vaccines. A total of 30 fowl pox vaccine samples were examined for the presence of REV using both in vitro and in vivo methods. In in vitro testing, the fowl pox vaccine samples were inoculated into chicken embryo fibroblast cultures prepared from specific-pathogen-free embryonated chicken eggs, and the cultures were examined using PCR to detect REV. In in vivo testing, each fowl pox vaccine sample was inoculated into 5-d-old specific-pathogen-free chicks, which were kept under observation for up to 12 wk postinoculation; serum samples were collected at 15, 30, and 45 d postinoculation for the detection of REV-specific antibodies using ELISA. Tissue samples were collected at 8 and 12 wk postinoculation for histopathological examination. Of the tested vaccines, only one imported vaccine sample tested positive for REV using PCR. Serum samples collected from chicks infected with the PCR-positive vaccine batch also tested positive for REV-specific antibodies using ELISA. Histopathological examination of the liver, spleen, and bursa of Fabricius demonstrated the presence of tumor cells in these organs, confirming the results obtained using PCR and ELISA, and indicating that the sample was contaminated with REV. These data clearly indicate that the screening of all commercial poultry vaccines for viruses is an important factor in assuring the biosafety of animal vaccines.

Isolation and analysis of a very virulent Marek’s disease virus strain in China

“…In order to verify the absence of infection of chickens with avian leukosis virus (ALV) and reticuloendotheliosis virus (REV), all the samples for amplification of MDV Meq and vIL-8 genes were also detected by previously reported PCR method for ALV [13] and REV [14]. …”

Avian Immunosuppressive Diseases and Immunoevasion

“…It has been known for a long time that fowlpox viruses (FWPV) can carry replication-competent REV genomes, which may be expressed in vivo [174,175]. It is therefore surprising that FWPV vaccines are still frequently contaminated with REV [176,177], suggesting a lack of quality control. The presence of REV in FWPV or FWPV vaccines can result in immunosuppression causing outbreaks of fowlpox, as suggested by Motha and Egerton [178].…”

Probable Congenital Transmission of Reticuloendotheliosis Virus Caused by Vaccination with Contaminated Vaccines

“…In the 1970s, the use of Marek’s disease (MD) vaccines accidentally contaminated with REV had been reported to induce a runting disease characterized by immunodepression and abnormal feathering in the vaccinated flocks in Japan and Australia [7]–[9]. Fadly and Witter [10] proved by in vivo and in vitro test that REV was a contaminant in a live virus fowl pox (FP) vaccine of poultry in 1997; Awad et al [11] reported that one of the 30 detected FP vaccine samples was contaminated by REV in 2010. However, up to the present, there are few reports on Newcastle disease (ND) vaccines or infectious bronchitis (IB) vaccines of poultry contaminated with REV.…”