Serological and molecular identification of Reticuloendotheliosis virus (REV) in chickens in Sudan

Abstract

Background: Reticuloendotheliosis virus (REV) is a gammaretrovirus that belongs to the family of Retroviridae. The infection can result in immunosuppression, runting syndrome, high mortality, acute reticular cell neoplasia or T- and/ or B-cell lymphoma, in a variety of domestic and wild birds. The disease is widespread around the world. No related data have been reported in Sudan about the disease. The present study was conducted to determine the prevalence of REV antibodies and DNA in local and commercial breeds of chickens older than 20 weeks from June 2014 to February, 2017.

Methods: A total of 460 sera samples and 150 (50 liver and 100 spleen) tissue samples were collected from local and commercial breeds of chickens older than 20 weeks and screened for anti-REV antibodies in four states of Sudan using a commercial REV antibody ELISA test kit (IDEXX). Polymerase chain reaction (PCR) was performed to detect REV DNA in tissue samples in Khartoum State.

Results: The results revealed that the overall seroprevalence of REV was 74.6% among local and commercial chicken breeds, but in commercial it was 79.5% (190/239) and 69.2% in local breeds (153/221). One hundred and fifty tissue samples of chickens (50 liver, 100 spleen) were tested using PCR for detection of REV using primer sets of the conserved region in envelope glycoprotein (env) gene with a band length of 850 bp. Five out of 50 (10%) liver samples were RE provirus DNA positive detected by PCR, whereas 15 out of 100 (15%) spleen samples were PCR positive. Univariate analysis revealed there was a difference (p ≤ 0.05) between locality and breed of chickens and seropositivity to REV.

Conclusions: The prevalence of the disease was high in Sudan and more studies are needed to evaluate the epidemiology and pathogenesis of the virus.

Keywords: ELISA; PCR; Reticuloendotheliosis virus (REV); Sudan; chickens; prevalence.

Figure 1

Agarose gel electrophoresis of the products amplified with PCR using the specific primers for reticuloendotheliosis virus. M; 100 bp DNA ladder, Lane 1; positive control, Lane 2, 3, 5; positive samples, Lane 4; negative sample, Lane 6; negative control