Variable persistence of the contagious equine metritis organism in the genital tract of CBA/J, CBA/N, LAF1/J, BALB/c and congenitally thymus-deficient (nude) mice.
Five inbred strains of mice, CBA/J, CBA/N, LAF1, BALB/c and congenitally thymus-deficient nude mice of BALB/c background, varied considerably in their susceptibility to the contagious equine metritis organism (CEMO). Whereas all the strains were virtually refractive to vaginal challenge, LAF1 and CBA/N mice were readily infected by intra-uterine inoculation. Based on infection rate and nature of the bacteriological response, CBA/N mice appeared the more susceptible of the 2 strains. Attempts to transmit CEMO to thymus-deficient nude mice were unsuccessful by both of these routes of challenge and by intraperitoneal inoculation, indicating that host resistance to the causal agent is independent of thymus-mediated immune phenomena. No clinical evidence of infection was observed in any of the experimentally infected mice. Although persistence of CEMO in the female reproductive tract varied widely, it could be isolated from some of the CBA/N mice for as long as 19 weeks after challenge by the intra-uterine route. The organism was cultured from the ovaries and/or oviducts of a high percentage of one group of CBA/N mice after 50 days, when it could no longer be recovered from the remainder of the genital tract. Limited attempts to achieve venereal transmission of CEMO between culture-positive female and companion male CBA/N mice were unsuccessful. The relative susceptibility of the CBA/N strain of mice to CEMO would suggest that host resistance to this infection is at least partly dependent on the presence of a fully functional B lymphocyte system. Further studies in this experimental model may elucidate some of the immunological mechanisms underlying development of resistance in the horse, more specifically as they relate to the occurrence of the carrier state in this disease.
D000818:Animals; D001424:Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D005260:Female; D005831:Genital Diseases, Female / Q000382:microbiology / Q000662:veterinary*; D005836:Genitalia, Female / Q000382:microbiology; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D012749:Sexually Transmitted Diseases / Q000382:microbiology / Q000662:veterinary*