ABSTRACT
The genomic DNA extracted from chicken embryo fibroblasts (CEF) of SPF chickens from three chicken farms was used as template to amplify the ALV proviral DNA by PCR with four pairs of primers, high positive detection rates of gag - gene (29/46), pol - gene (27/46), env - gene (24/46) and LTR fragment (31/46) were achieved. Eight continuous and overlapping fragments were amplified from one DNA sample with 8 pairs of primers according to published sequences, then cloned into the TA vector and se quenced. The complete sequence of the whole genome of ALV strain SD0501 was established and analyzed with DNAstar software. Comparisons of SD0501 sequence with that of other representative endogenous avian virus strains demonstrated that the genomes of ALV were relatively conservative, the nucleotide identity of all the strains was over 99.1%, and env - gene was over 98.5%. However, a low identity was demonstrated among the representative strains of different subgroups, especially, the env - gene showed obvious difference, the corresponding identity was as low as 56.3% - 91.5%.
Subject(s)
Animals , Chick Embryo , Avian Leukosis Virus , Genetics , Base Sequence , Genome, Viral , Polymerase Chain Reaction , Proviruses , Genetics , Sequence Analysis, DNA , Specific Pathogen-Free Organisms , Terminal Repeat SequencesABSTRACT
The isolate GN52 of Riemerrella anatipestifer was passaged on the Martin Medium successively according to the optimum condition. The experiments included Gram staining, biochemical test, drug sensitivity test and animal experiments were carried out on the bacteria of 3rd, 11th, 21st, 31st, 41st, 51st and 61st generations. It indicated that the bacterial morphs, biochemical character, drug resistance of the strain had no obvious change, but the virulence showed a trend of reduction.