Studies on some avian viruses with special refence to aheat resistantnewcastledisease virus

Results obtained during this investigation under experimental conditions mentioned-could be summarized as follows: 1- from 17 previously isolated viruses only 9 isolates could be propagated andidentified as IB, Reo and Pox viruses in single, double and triple infections. The failure in propagating the other 8 isolates was discussed.2- Pathogenesis of VG/Ga and B 1 B 1 NDV strains in two-week-old SPF whiteleghom chickens revealed that both viruses behaved similarly as they failed to initiate any clinical signs in inoculated birds although they could be reisolated for 5 to 10 days Pi.3- Transmission of VG/Ga and BIB 1 strains in day-old white Leghom chicksrevealed lateral spread of infection for 3 to 9 days post contact. Thepersistence of BIB 1 in the respiratory tract was longer than VG/Ga. Bothviruses were shed for 3 - 6 days through the intestinal tract.4- Seroconversion results showed that two-week old SPF birds infected with VG/Ga and BIB 1 NDV strains peaked at 2 weeks Pi, GMT (80), aconsiderable HI titer (30) was observed at 5 weeks Pi while day-old SPFbirds showed comparatively lower figures of GMT. 5- Antigen localization detection using ABC-IP and indirect IF staining technique showed that VG/Ga and BIB I antigens were detected in the cytoplasm of the epihtelial cells especially the mucous producing addition to other macrophage like cells (in submucosa of trachea, bronchiand in between air vesicles). Both strains were detected in the tracheal,pulmonary and intestinal tissues for 10 to 15 days Pi or contact.