title: Restriction enzyme analysis of the virulence plasmids of VapA-positive Rhodococcus equi strains isolated from humans and horses.
abstract: Restriction enzyme digestion patterns of the large virulence plasmids of 8 human and 37 foal isolates of virulence-associated protein (VapA)-positive Rhodococcus equi strains from different sources were compared. Foal isolates came from five continents. Digestion with EcoRI divided these plasmids into three closely related types, and digestion with BamHI divided them into three major types which corresponded to the EcoRI types. The only EcoRI and BamHI type 3 plasmid was from a single foal isolate obtained from Japan. There are thus two major but related virulence plasmids in isolates from foals. Geographic differences were noted, since foal isolates with the EcoRI type 1 plasmid digestion pattern tended to come mostly from the United States, Canada, European countries, India or Zimbabwe and foal isolates with EcoRI type 2 pattern tended to come mostly from Latin American countries. Only 8 of 38 different human isolates, mostly from AIDS patients, were VapA positive, in contrast to 37 of 42 foal isolates. VapA-positive isolates from humans possessed virulence plasmids of either EcoRI type 1 or EcoRI type 2. These results confirm that only a small proportion of human patients with R. equi infections acquire foal virulent R. equi.
authors.affiliation: Department of Pathobiology, University of Guelph, Ontario, Canada.
authors.forename: V M
authors.initials: VM
authors.lastname: Nicholson
authors.forename: J F
authors.initials: JF
authors.lastname: Prescott
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology; D000193:Actinomycetales Infections / Q000150:complications / Q000382:microbiology / Q000662:veterinary; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004262:DNA Restriction Enzymes; D006734:Horse Diseases / Q000382:microbiology; D006736:Horses / Q000382:microbiology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics; D010957:Plasmids / Q000235:genetics / Q000302:isolation & purification; D016929:Rhodococcus equi / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D013045:Species Specificity; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D037521:Virulence Factors; D004262:DNA Restriction Enzymes