Analysis of unintegrated avian RNA tumor virus double-stranded DNA intermediates

Abstract

Previous studies by Guntaka et al. have shown that the unintegrated DNA intermediates of avian RNA tumor virus replication can be readily isolated from cultures of the quail tumor line QT-6 at 1 day after infection. The intermediates include double-stranded linear and covalently closed circular DNA species. Using the analysis procedure of Southern together with previously obtained information regarding the sites of action of certain restriction endonucleases on avian sarcoma virus DNA, we have further characterized the viral DNA intermediates. Evidence is presented that, relative to the RNA genome, most of the linear species possess a direct terminal sequence redundancy equivalent to 0.5 x 106 ± 0.3 x 106 daltons of double-stranded DNA. Some of the circular forms also possess a sequence redundancy of 0.21 x 106 ± 0.03 x 106 daltons.

Characterization of avian myeloblastosis-associated virus DNA intermediates

“…This indicates that the 0.9-Md fragment corresponds to the 3' end of the viral RNA. The limited homology of the 1.8-Md fragment with the 3' probe despite its location at the opposite end of the linear genome indicates that the MAV viral DNA contains a terminal redundancy, as does the DNA from other retroviruses examined so far (9,11,18).…”

“…Three different forms of viral DNA have been identified in avian retrovirus-infected avian cells: linear DNA molecules of approximately 6.2 megadaltons (Md), circular DNA molecules of approximately the same mass (1,9,18), and proviral DNA integrated into the host genome (1,13,23,24). The length of cytoplasmic linear proviral DNA synthesized in avian sarcoma vi-rus-infected Japanese quail cells approximates a complete linear copy of one subunit ofthe viral RNA (18).…”

“…The length of cytoplasmic linear proviral DNA synthesized in avian sarcoma vi-rus-infected Japanese quail cells approximates a complete linear copy of one subunit ofthe viral RNA (18). Restriction enzyme analysis of avian sarcoma virus DNA has shown that the termini of the linear viral DNA bear a sequence redundancy of approximately 300 nucleotides (9,18) and that the integrated proviral DNA is colinear with respect to the unintegrated linear DNA (10,16). In addition, it has been shown that the DNA of various avian sarcoma virus strains can be differentiated on the basis of their restriction enzyme cleavage sites (18,22).…”

Intracisternal A-particle genes: structure of adjacent genes and mapping of the boundaries of the transcriptional unit

“…These sequences are thought to play an important role in the reverse transcription of the viral RNA. Both double-stranded circular and integrated forms of retroviruses have a much longer terminal redundancy (LTR) which includes the strong stop sequences and a portion of the 3' end of the RNA (8,10,20,23). The ends of the genomic RNA thus map to the middle of the LTRs, and these sequences appear to be involved in integration as well as initiation and termination of transcription.…”

Reverse transcription of avian sarcoma virus RNA into DNA might involve copying of the tRNA primer

“…1. This is the only PvuI site on the genome, although there are two copies on the completed double-stranded DNA (5,11). From recent sequencing studies of D. Schwartz and W. Gilbert (personal communication), we now know the precise location of the PvuI and EcoRI sites.…”