title: Common occurrence of Gallid herpesvirus-2 with reticuloendotheliosis virus in chickens caused by possible contamination of vaccine stocks.
abstract: OBJECTIVE
  The aim of this study was to investigate the common occurrence of reticuloendotheliosis virus (REV) among Gallid herpesvirus 2 (GaHV-2) infected chickens. The possible cause of this co-occurrence may be linked to contaminated vaccine stocks, which were also examined.
  
  
  RESULTS
  The study was conducted on 25 field isolates of GaHV-2 collected between 2007 and 2013 from vaccinated chickens. Additionally, 10 commercial Marek's Disease vaccine stocks manufactured between 1993 and 2013, comprising of FC126 HVT, CVI988/Rispens and bivalent HVT + Rispens vaccines were examined. Chicken isolates were collected from the liver. Due to difficulties in differentiation between GaHV-2 and REV, by observation of clinical signs or lesions presented in liver or spleen, loop-mediated isothermal amplification (LAMP and RT-LAMP) as well as PCR-based methods were applied.
  
  
  CONCLUSIONS
  The co-occurrence of GaHV-2 and REV genetic material was shown in 24 (96%) of 25 examined isolates. A marginal REV contamination was detected in three out 10 (30%) commercial vaccine stocks, mainly in bivalent HVT + Rispens vaccines produced between 2009 and 2012.
  
  
  CONCLUSIONS
  Our results indicated the common occurrence of GaHV-2 and REV in Polish chicken flocks, which is probably linked to contaminated HVT + Rispens vaccine stocks. Reasons for the detection of a marginal REV contamination need to be further elucidated.
authors: Department of Poultry Viral Diseases, National Veterinary Research Institute, Puławy, Poland.
authors: G
authors: G
authors: Woźniakowski
authors: A
authors: A
authors: Mamczur
authors: E
authors: E
authors: Samorek-Salamonowicz
mesh_terms: D000818:Animals; D002645:Chickens; D060085:Coinfection / Q000209:etiology / Q000821:virology; D004340:Drug Contamination; D008381:Herpesvirus 2, Gallid / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D008380:Marek Disease / Q000517:prevention & control / Q000821:virology*; D011201:Poultry Diseases / Q000821:virology*; D001356:Reticuloendotheliosis virus / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D012192:Retroviridae Infections / Q000209:etiology* / Q000821:virology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D014765:Viral Vaccines
keywords: Gallid herpesvirus-2; chickens; co-occurrence; loop-mediated isothermal amplification; reticuloendotheliosis virus; vaccine contamination