Turkey adenovirus 3 (TAdV-3) belongs to the genus Siadenovirus, family Adenoviridae. Previously, nucleotide
sequencing and annotation of the Virginia avirulent strain (VAS) of TAdV-3 genome, isolated in our laboratory,
indicated the presence of a total of 23 genes and open reading frames (ORFs). The goals of this study were 1) to
delineate the growth kinetics of the virus using a qPCR-based infectivity assay, and 2) to determine the virus
gene expression profile during the early and late phases of infection in target B lymphocytes. The one-step
growth curve experiment demonstrated 3 phases of virus replication cycle: a lag phase lasted for 12–18 h postinfection
(h.p.i.), in which the virus titer declined; a log phase from 18 to 120 h.p.i., in which the number of
infectious virus particles increased over 20,000 folds, and a brief decline phase thereafter. Southern blot analysis
indicated that the synthesis of new viral DNA started by 8 h.p.i. Gene-specific RT-PCR analysis revealed the
expression of mRNAs from the 23 TAdV-3 genes/ORFs. According to the temporal transcriptional profiling of
TAdV-3 genome, genes could be divided into 3 groups based on the time of transcription initiation: group 1
showed detectable levels of transcription at 2 h.p.i and included 7 genes, i.e., hyd, III, pX, pVI, II, 100 K, and
33 K; group 2 included 12 genes whose mRNAs were detected for the first time at 4 h.p.i., i.e., ORF1, IVa2, pol,
pTP, pIIIa, EP, DBP, E3, U exon, IV, ORF7, and ORF8; group 3 of transcripts were detectable starting 8 h.p.i. and
included only 4 genes, i.e., 52 K, 22 K, pVII, and pVIII. Our data suggest that the transcriptional kinetics of genus
Siadenovirus differ from that observed in other adenoviral genera; however, a few TAdV-3 genes showed similar
expression patterns to their adenoviral homologs. |
