Arenavirus recombination: The formation of recombinants between prototype pichinde and pichinde munchique viruses and evidence that arenavirus S RNA codes for N polypeptide

Abstract

The ability of arenaviruses to form recombinant viruses by viral RNA segment reassortment has been investigated using a cloned, high-temperature adapted strain of prototype Pichinde virus (PIC), and a cloned, alternate Pichinde virus topotype named Pichinde Munchique (designated MUC). The oligonucleotide fingerprints of the large and small viral RNA segments of the two viruses can be easily distinguished. The virion RNA species of cloned wild-type progeny viruses recovered from dual wild-type PIC and MUC coinfections of BHK-21 cells have been analyzed by oligonucleotide fingerprinting. Other than PIC and MUC genotypes, progeny virus clones were found with PIC/MUC (large/small) RNA segment genotypes, indicating that these recombinant arenaviruses were formed by RNA segment reassortment. Dual infections of BHK-21 cells with a temperature-sensitive (ts), conditional lethal, mutant of MUC and the Group I ts mutants of PIC (but not the PIC Group II ts mutants), have yielded wild-type progeny viruses at high frequency. Genotype analysis of one of these recombinant progeny showed that it had a PIC/MUC genotype. This result indicated that the Group I mutants of PIC have a defective small viral RNA segment, and that the MUC ts mutant (and probably the PIC Group II ts mutants) has a defective large viral RNA segment. Plaque size analyses of the parental wild-type and reassortment viruses have shown that the plaque size of the reassortants was determined by the large viral RNA segment. Tryptic peptide analyses of the nucleocapsid (N) polypeptide of the PIC/MUC recombinant by comparison to similar analyses for PIC and MUC indicate that the recombinant has a MUC N polypeptide, i.e., that the viral S RNA codes for N polypeptide.