Affiliation:
1. Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50010
Abstract
ABSTRACT
A bacterial plasmid containing 1.75 copies of double-stranded porcine circovirus (PCV) DNA in tandem (0.8 copy of PCV type 1 [PCV1], 0.95 copy of PCV2) with two origins of DNA replication (Ori) yielded three different DNA species when transformed into
Escherichia coli
: the input construct, a unit-length chimeric PCV1
Rep
/PCV2
Cap
genome with a composite Ori but lacking the plasmid vector, and a molecule consisting of the remaining 0.75 copy PCV1
Cap
/PCV2
Rep
genome with a different composite Ori together with the bacterial plasmid. Replication of the input construct was presumably via the theta replication mechanism utilizing the ColE
1
Ori, while characteristics of the other two DNA species, including a requirement of two PCV Oris and the virus-encoded replication initiator Rep protein, suggest they were generated via the rolling-circle copy-release mechanism. Interestingly, the PCV-encoded Rep′ protein essential for PCV DNA replication in mammalian cells was not required in bacteria. The fact that the Rep′ protein function(s) can be compensated by the bacterial replication machinery to support the PCV DNA replication process echoes previous suggestions that circular single-stranded DNA animal circoviruses, plant geminiviruses, and nanoviruses may have evolved from prokaryotic episomal replicons.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Cited by
56 articles.
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