Pathology and transmission of experimental velogenic newcastle disease (ND) virus in the japanese quail (Coturnix coturnix japonica)

An experimental study was undertaken to investigate the clinico-pathological alterations of Newcastle Disease (ND) in Japanese quail under normal and stress conditions. A total of 90 Japanese quail chicks of 13-day-old were randomly divided into three groups of 30 chicks each and fed commercial quail feed. At 37 days old, one group received 100ul of velogenic Newcastle Disease Virus (vNDV) only via the oro-nasal route (VNDO). Another group received three (3) intramuscular dexamethasone injections (to mimic a stress response) prior to receiving 100ul of vNDV challenge (DNVND) dose. Chicks in the third group served as control (CON), and received oro-nasal drops of distilled water only. Grossly, quail chicks from groups VNDO and DNVND developed atrophied ovaries and testes, unlike birds in CON. Representative sections of the testes and ovaries from infected groups showed collapse of the seminiferous tubules and ovarian follicles. Female quails from VNDO and DNVND laid no eggs, unlike those from CON, who laid eggs consistently from six (6) weeks of age. Additionally, in comparison to male birds of VNDO group, Sertoli cells of DNVND males showed vacuolation and synplastic spermatids in the tubular lumina. Results of our study clearly demonstrates that vNDV has predilection for gonads (testis and ovary) of quails and causes significant pathological alterations in their anatomical architecture and function. Furthermore, infected stressed birds showed less gonadal pathological changes in contrast to infected non-stressed quails.