EID50

Six SPF chickens were infected with vNDV by intranasal administration of 0.1 mL 105 EID50 /0.1 mL of AF2240 isolate.

The remaining birds in each group were challenged with 105 embryo infective dose 50 (EID50) of IBH-HPS virus orally at 21 days post-vaccination.

EID50 was calculated according to Reed and Muench (12).

This group was further subdivided into two groups having 25 birds each i.e.Group C1 not challenged and group C2 Challenged against Virulent ND virus10 4 EID50, 0.1 ml/chick.

Each of 20 chickens were inoculated with 105.3 EID50 in 0.1 mL of virus, divided into the right nares (50 %) and both the eyes (25% each).

The birds in group A were commercial broiler chicks having maternal derived antibodies and were challenged with IBDV field isolate at the rate of 0.1ml of EID50 (virus titer 105.50/100l) on 2nd week of age through eye drops.

Egg Infective Dose 50 (EID50) for NDV and AIV was found 109.16 EID50 and 109.46 EID50 per ml respectively, calculated following Spearman and Karber method (1974).

Median embryo infectious dose (EID50) was calculated using previously reported methods (Reed and Muench, 1938).

For isolation of IBD virus, 10 day-old embryonated chicken eggs were inoculated through chorio-allantoic membrane (CAM) at dose rate of 0.2ml of IBDV inoculum having titer of (EID50 105.50/100ul) (0.1 ml virus suspension + 0.1 ml antibiotic mixture).

The chicken embryo died within 2-5 days post inoculation and showing IBV specific lesions were harvested allantoic fluid and 50% chicken infectious dose (EID50) was calculated 103 EID50 by inoculation of serial 10 fold dilution of virus in 10-day-old SPF embryonated chicken eggs.

Virus quantitation was performed by calculating embryo infectious dose50 (EID50) through a previously described method (Dennis 2008).