A model for intramolecular recombination of herpesvirus DNA leading to the formation of circular, circular-linear and fragmented genomes

Polymerase chain reaction amplification of herpes simplex viral DNA from the geniculate ganglion of a patient with Bell's palsy

Bell's palsy is the most common cause of facial paralysis. In this study, we demonstrate the presence of herpes simplex viral type 1 (HSV-1) genomic DNA in the geniculate ganglion of a patient who had Bell's palsy. This association suggests that in this patient, HSV-1 may have caused Bell's palsy. If HSV-1 is a cause of Bell's palsy, treatment with acyclovir may be beneficial. Additional studies should be done to establish the prevalence of HSV-1 as an etiologic agent of Bell's palsy.

Comparison of the DNA sequence and secondary structure of the herpes simplex virus L/S junction and the adeno-associated virus terminal repeat

The defective parvovirus Adeno-associated virus (AAV) is absolutely dependent upon coinfection with either Adenovirus or Herpes Simplex Virus (HSV) for its multiplication. We have compared the terminal repeats of HSV-1F strain DNA with the terminal 200 nucleotides of AAV DNA. Our findings demonstrate similarities between portions of the HSV inverted repeats found at the L/S junction and the termini of AAV. By computer analysis we have determined potential secondary folding patterns for both genomes. The following points can be made about the a, b, and c repeats in HSV: (1) Regions b and c are complementary over a significant portion of their length. (2) The ends of a can fold back on themselves to form large secondary structures. Moreover, when the b and c homology is used to align the ends of a, the b/a and c/a junctions are within 1 base of each other. (3) The short direct repeats within a are essentially a large loop with little secondary structure. The potential implications of this structure are discussed and a model for HSV DNA replication is presented.

Recombination occurs mainly between parental genomes and precedes DNA replication in pseudorabies virus-infected cells

The experiments described in this paper were part of an attempt to determine the mechanisms involved in the isomerization of the pseudorabies virus genome. To this end, [(14)C]thymidine-labeled parental virus DNA that was transferred to progeny virions produced by cells incubated in medium containing bromodeoxy-uridine was analyzed in neutral and alkaline CsCl density gradients. The buoyant density of the (14)C-labeled DNA indicated that the parental DNA strands had retained their integrity and had not undergone breakage and reunion with progeny DNA strands; neither massive intermolecular nor intramolecular recombination had occurred after replication of the DNA. Whereas breakage and reunion between parental and progeny virus DNA strands were not detectable, these processes were observed between differentially density-labeled parental DNAs. Furthermore, the frequency of recombination between progeny DNAs accumulating in the cells was low. These results indicate that in pseudorabies virus-infected rabbit kidney cells recombination occurs mainly between parental genomes and precedes DNA replication. An analysis of the kinetics of appearance of recombinants between pairwise combinations of temperature-sensitive mutants also indicated that recombination is an early event. The ratio between the number of recombinant virions and the number of temperature-sensitive mutant virions produced by the cells remained the same throughout infection. Since the relative amounts of viral DNAs synthesized early and late during the infective process that were integrated into virions were approximately the same, it appears that late viral DNA did not experience an increased number of recombinational events compared with early viral DNA. These results, which reinforce the conclusion reached from the results of the analysis of the behavior of the parental DNA molecules in density shift experiments, indicate that recombination is an early event.