Experimental infections of mice and pigs with Streptococcus suis type 2.
Five inbred strains of mice were tested for their susceptibility to Streptococcus suis type 2 including the type strain, two isolates from meningitis in pigs and two isolates from tonsils of clinically healthy pigs. C57BL/6, ICR and ddY strain mice showed lower susceptibility to all strains of S. suis type 2 than BALB/c and SS strain mice. The type strain and the isolates from diseased pigs produced septicaemia and meningitis in BALB/c and SS mice inoculated with 10(8) colony forming unit of the bacteria and 60 to 100% of these infected mice died. On the other hand, mice inoculated with the isolates from healthy pigs showed mild clinical signs but none of them died. In BALB/c mice which died or developed nervous signs, the purulent meningo-encephalitis, myocarditis, ophthalmitis, labyrinthitis and otitis media were observed. S. suis type 2 antigen was demonstrated in these lesions by immunoperoxidase staining using rabbit S. suis type 2 antiserum. These results were similar to those in the experimentally infected pigs with these virulent and avirulent strains against mice. These results indicate that BALB/c and SS strains of mice are useful as an experimental model of S. suis type 2 infections in pigs, and that there are virulent and avirulent strains against mice and pigs among the strains of S. suis type 2.
Kataoka
Y
Y
National Institute of Animal Health, Ibaraki, Japan.
Haritani
M
M
Mori
M
M
Kishima
M
M
Sugimoto
C
C
Nakazawa
M
M
Yamamoto
K
K
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008815:Mice, Inbred Strains; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D017011:Streptococcus suis / Q000472:pathogenicity*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000473:pathology; D013556:Swine, Miniature; D014774:Virulence