ABSTRACT
We have measured the spontaneous production of mutants in derivatives of herpes simplex virus type 1 resistant to phosphonoacetic acid. Six such derivatives produced 9- to 123-fold fewer iododeoxycytidine (ICdR-)-resistant progeny (i.e., thymidine kinase deficient) than their wild-type parents. To locate the mutation which controls mutant production in one of the strains (PAAr-5), we constructed phosphonoacetic acid-resistant, recombinant viruses by marker transfer, using wild-type viral DNA and DNA restriction fragments conferring the resistance phenotype. The resultant recombinants also produced very low levels of ICdR-resistant progeny during growth, indicating a close linkage (within 1.1 kilobase pairs) between the drug resistance locus and the sequences controlling production of mutant progeny. Evidence is presented that the low mutant yield in PAAr-5 is not due to abnormal expression of mutants, hypersensitivity to ICdR, altered thymidine kinase activity, or slow replication rates. Since the locus conferring resistance to phosphonoacetic acid in PAAr-5 has been shown previously to be the DNA polymerase gene, we hypothesize that the reduced yield of mutants results from enhanced replication fidelity by the altered DNA polymerase. The existence of antimutator derivatives of herpes simplex indicates that the observed high mutation rate for wild-type strains is an intrinsic property of the virus and may provide a selective advantage during growth in animal hosts.
Subject(s)
DNA-Directed DNA Polymerase/genetics , Genetic Variation , Simplexvirus/genetics , Cell Line , Chromosome Mapping , Drug Resistance, Microbial , Mutation , Phenotype , Phosphonoacetic Acid/pharmacologySubject(s)
Aging , DNA Repair , Aged , Caffeine/pharmacology , Cell Line , Child, Preschool , DNA, Viral , Fibroblasts/drug effects , Fibroblasts/radiation effects , Humans , Infant , Infant, Newborn , Methyl Methanesulfonate/pharmacology , Models, Biological , Simplexvirus/genetics , Trioxsalen/pharmacology , Ultraviolet RaysSubject(s)
DNA-Directed DNA Polymerase/genetics , Mutation , Simplexvirus/enzymology , Bromodeoxyuridine/pharmacology , Cells, Cultured , Drug Resistance, Microbial , Recombination, Genetic , Simplexvirus/genetics , Suppression, Genetic , Temperature , Thymidine Kinase/analysis , Thymidine Kinase/geneticsABSTRACT
Washing the red cells before preparation of the hemolysate is important in avoiding serious clinical errors in fetal hemoglobin determinations. This has been demonstrated using both the alkali denaturation technique and a commercial hemolyzing reagent. Hemolysates prepared from unwashed cells were always above the normal range in samples known to be normal.
