Further studies on vertical transmission of reticuloendotheliosis virus in turkeys

Turkey hens were inseminated with infected semen from REV tolerant turkey stags at weekly intervals for 6 weeks, and subsequently with semen from uninfected control stags for a further 6 weeks. Cell cultures prepared from eggs produced during the experimental period were assayed for REV by an indirect fluorescent antibody test. Poults hatched from such eggs were also assayed for REV at 1 day of age or maintained to 28 weeks of age to study lateral spread of virus to uninfected hatch mates. REV was detected in 27.5% of embryos from hens inseminated with REV infected semen and 8.7% of 1-day-old poults hatched were found to be viraemic. Following the change to insemination with uninfected semen, REV was detected in 0.7% of embryos examined. REV was isolated from the lower oviduct of two of 18 hens, 12 weeks after first insemination with infected semen. REV spread readily to uninfected poults maintained in contact with progeny of hens inseminated with REV-infected semen, in that 50% had neutralising antibody by 8 weeks of age. At 28 weeks of age the leukosis mortality in such poults was 16%.