An Outbreak of Lymphomas in a Layer Chicken Flock Previously Infected with Fowlpox Virus Containing Integrated Reticuloendotheliosis Virus

Abstract

Visceral lymphomas occurred in a 236-day-old layer flock previously diagnosed with reticuloendotheliosis virus (REV)-integrated fowlpox virus (FPV) infection at the age of 77 days. Common pathologic lesions were multiple neoplastic nodules of homogeneous lymphocytes in the livers and spleens of all submitted chickens. All neoplastic tissues were positive for the REV envelope (env) gene by PCR. In a retrospective molecular study of FPV-infected 77-day-old chickens from the same flock, we identified nearly full-length REV provirus integrated into the genome of FPV as well as the REV env gene in trachea samples, whereas only the REV LTR region was present in the FPV strain used to vaccinate this flock. The 622-bp REV env gene nucleotide sequence derived from the trachea and neoplastic tissues was identical. Commercial ELISA of serum samples revealed that all chickens aged between 17 and 263 days in this flock were positive for REV but not for avian leukosis virus. Taken together, the evidence suggests that the visceral lymphomas were caused by a REV-integrated FPV field strain. FPV infections of commercial chickens should be followed up by careful monitoring for manifestations of REV infection, including lymphomas and immune depression, considering the ease with which the REV provirus appears to be able to integrate into the FPV genome.

Soluble expression and enzymatic activity evaluation of protease from reticuloendotheliosis virus

“…Moreover, REV-related vaccine contamination has been reported for Marek's disease and fowl pox [23][24][25][26]. Therefore, REV infection should be studied more thoroughly.…”

TRIM62 From Chicken as a Negative Regulator of Reticuloendotheliosis Virus Replication

“…CEF cells were incubated with a diluted stock of SNV strain of REV (China strain: JX0927, maintained in our laboratory) at a multiplicity of infection (MOI) of 0.1. The mRNA expression of TRIM62 and REV in CEF cells were detected at different times (12,24,48,72, and 96 h post-infection). The mRNA expression of TRIM62 in the supernatant was also detected in parallel at the same sampling times.…”

“…Reticuloendotheliosis virus (REV) is an avian retrovirus that can induce immunosuppression, runting syndrome, lymphomas, and acute reticulum cell neoplasia (8,9). The occurrence of reticuloendotheliosis (RE) has an immunosuppressive effect and REV as the contaminant within vaccines against Marek's Disease (MD) (10), fowlpox (11,12), and Gallid herpesvirus 2 (GaHV-2) (13), which may lead to vaccination failures and co-incidence of RE with other secondary infectious agents. Since breeder and layer flocks are commonly vaccinated against MD, the possible congenital transmission of REV between chickens was also be taking into account.…”

Common occurrence ofGallid herpesvirus-2with reticuloendotheliosis virus in chickens caused by possible contamination of vaccine stocks

“…; Koo et al . ). In infected cells, the proviral DNA of REV may be integrated into the genome of GaHV‐2 (Witter et al .…”

“…A further factor in the importance of REV is its presence as the contaminant within vaccines against MD and smallpox, caused by fowl pox virus (FPV) (Diallo et al 1998;Koo et al 2013). In infected cells, the proviral DNA of REV may be integrated into the genome of GaHV-2 Cui et al 2010;Sun et al 2010a,b;Mays et al 2012;Wei et al 2012;Lupiani et al 2013).…”