 This does not, however, apply to M-CoVs in general, as other members like PV (Puffinosis coronavirus) retain a functional version of this gene.Genetic recombination can occur when at least two RNA viral genomes are present in the same infected host cell.RNA-RNA recombination between different strains of the murine coronavirus was found to occur at a very high frequency both in tissue culture and in the mouse central nervous system.