Comparison of the physical and genetic maps of pseudorabies virus shows that the genetic map is circular
Ihara, S.; Ladin, B.F.; Ben-Porat, T.
Virology 122(2): 268-278
1982
ISSN/ISBN: 0042-6822 PMID: 6293175 DOI: 10.1016/0042-6822(82)90226-4
Accession: 001056773
Temperature-sensitive mutants of pseudorabies (Pr) virus belonging to 19 different complementation groups were physically mapped by marker rescue. While many of the mutations appear to be clustered, mutations in various regions of the long unique sequence and 1 mutation in the inverted repeats were identified. Mutants located in different parts of the genome were crossed with one another and genetic linkage maps were constructed. Internally consistent results were obtained when relatively closely linked markers were crossed and the mutant could be arranged in a linear order. When markers on either the left or the right side of the genome were crossed with markers located in the center of the genome, similar linear arrays could be constructed. Piecing together overlapping segments of the partial linkage maps revealed that the same markers reappear on both sides of the genetic map. Mutants which map toward the 2 opposite ends of the physical map of the genome behave as if they were closely linked when crossed directly with one another, indicating that the genetic map of Pr virus is circular. Pr virus has unique ends and therefore should not exhibit circular linkage between the various markers. Evidently, the genetic map has circular characteristics because molecules that have undergone an even number of recombinational events have a selective advantage in replication.