Virulence attenuation of a Mycobacterium avium subspecies paratuberculosis S-type strain prepared from intestinal mucosa after bacterial culture. Evaluation in an experimental ovine model.
The differences in pathogenicity between an inoculum derived directly from an intestinal tissue homogenate from a paratuberculosis affected sheep and the S-type Mycobacterium avium subsp. partuberculosis (Map) strain isolated in laboratory media from the mentioned homogenate were assessed in two experiments in lambs. Specific peripheral immune responses were significantly lower in animals inoculated with the cultured organisms that showed only granulomatous lesions in the intestinal lymphoid tissue. However, in the homogenate group, more abundant granulomata also occurred in the lamina propria. Map was isolated only in lambs infected with the culture strain. Map DNA was demonstrated by nested-PCR in all the lambs but in a lower proportion (57.1% vs 100%) in those from the culture group. Under these particular experimental conditions, the results suggest that an attenuation of Map virulence has occurred in the cultured strain compared to the initial tissue homogenate, even after a low number of passages.
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Miguel
M
Fernández
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Laetitia
L
Delgado
Departamento de Sanidad Animal, NEIKER-Tecnalia, Berreaga 1, 48160 Derio, Bizkaia, Spain.
Iker A
IA
Sevilla
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Miguel
M
Fuertes
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Pablo
P
Castaño
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Marcos
M
Royo
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
M Carmen
MC
Ferreras
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
Julio
J
Benavides
Departamento de Sanidad Animal, Instituto de Ganadería de Montaña (CSIC-ULE), Facultad de Veterinaria, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain. Electronic address: vperp@unileon.es.
Valentín
V
Pérez
D000818:Animals; D004269:DNA, Bacterial / Q000235:genetics; D007413:Intestinal Mucosa / Q000382:microbiology*; D023421:Models, Animal; D016927:Mycobacterium avium subsp. paratuberculosis / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D010283:Paratuberculosis / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology*; D014774:Virulence
D004269:DNA, Bacterial
Cultured strain; Experimental infection; Gut homogenate; Mycobacterium avium subsp. paratuberculosis; Sheep