Functional and molecular characterization of African swine fever virus mutants resistant to phosphonoacetic acid.
African swine fever virus (ASFV) growth and plaque formation were inhibited by phosphonoacetic acid (PAA) concentrations of 200 micrograms/ml or more. One spontaneous mutant and two mutants isolated from mutagenized virus were resistant to PAA inhibition and showed practically normal viral DNA synthesis in the presence of PAA. DNA polymerase activity present in the cytoplasmic fraction from cells infected with the mutants required 10-fold higher concentrations of PAA for inhibition compared to equivalent inhibition of the wild-type enzyme. Like wild-type virus, the PAA-resistant mutants were resistant to inhibition by aphidicolin. Marker rescue analysis with mutant DNA fragments covering different regions of the ASFV DNA polymerase gene mapped the mutations within a fragment which was cloned and sequenced. A single nucleotide and amino acid change was assigned to each mutant. Two of the PAA-resistant mutations lie within the highly conserved region II common to alpha-like DNA polymerases, which has been implicated in pyrophosphate binding and probably also in dNTP binding. The other mutation was localized to within a region of moderate homology among viral DNA polymerases close to one of the motifs allegedly considered as constituting the 3'-5' exonuclease active site.
Laboratory of Virology II, Gulbenkian Institute of Science, Oeiras, Portugal.
M I
MI
Marques
J V
JV
Costa
D000358:African Swine Fever Virus / Q000187:drug effects* / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D002522:Chlorocebus aethiops; D004279:DNA, Viral; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D005814:Genes, Viral; D005819:Genetic Markers; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010746:Phosphonoacetic Acid / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D014709:Vero Cells
D000998:Antiviral Agents; D004279:DNA, Viral; D005819:Genetic Markers; D004259:DNA-Directed DNA Polymerase; D010746:Phosphonoacetic Acid