Dynamic changes on shedding virus of experimental infection of chickens with avian influenza virus H5N1 subtype

In order to observe the dynamic changes on shedding virus of the experimental infection of chicken with the avian influenza virus (AIV) H5N1 subtype,180 non immunized Siqiza chickens of 28 days old were randomly divided into two groups with 90 chickens in each group,of which one group was challenged with AIV H5N1 subtype(A/Goose/GD/2/96,the LD 50 for non immunized Siquza chickens of 18 days old was 10 -5.4 ×0.2 ml) in a dosage of virus at 10 4×0.2 ml of allantoic fluid intramuscularly,and the other group was challenged with 0.2 ml sterile saline as control.Within the first 4 days after challenging,the clinical symptoms and the pathological changes were recorded every 6 hours,and from which two chickens were taken and killed.The specimens of internal organs such as brain,liver,spleen,kidney,pancreas and muscle as well as the cloacal swab and tracheal swab were taken for virus isolation.and the samples were collected every 12 hours 4 days after challenging till 11days thereafter.At the same time,sera were taken for the determination of anti AIV HAI antibody titres.It was found that AIV H5N1 subtype could be isolated from cloacal and tracheal swabs 18 hours after inoculation and lasted for 7 days,and could also be isolated from the mixed specimens of various viscera 36 hours after inoculation,and lasted for 10 days;no virus could be isolated from the muscle samples