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Clinical and Diagnostic Laboratory Immunology, Jul 1994, 450-463, Vol 1, No. 4
S Tzipori, W Rand, J Griffiths, G Widmer and J Crabb
Several immunodeficient rodent models currently exist in which persistent,
largely asymptomatic, Cryptosporidium parvum infections can be established.
Piglets, in contrast, develop a self-limiting diarrheal illness. We have
consequently developed an animal model system in which scid mice were used
to screen drugs for inhibitory activity against C. parvum, after which the
drugs' therapeutic potential was evaluated with piglets. Paromomycin and
hyperimmune bovine colostrum-immunoglobulin were selected to evaluate this
system. C. paravum infections in suckling scid mice tended to be associated
with villus surfaces, while in weaned and in older scid mice infections
were more commonly localized in abscessed crypts. Rates of oocyst shedding
in suckling scid mice were 50 to 200 times higher than in weaned mice and
therefore made suckling mice a considerably more sensitive model for drug
testing. Paromomycin given in high doses over 9 to 10 days was not toxic to
either scid mice (3,000 mg/kg of body weight per day) or piglets (500
mg/kg/day). Paromomycin treatment was very effective against villus surface
infections in suckling mice and considerably less effective against
infections in inaccessible sites such as abscessed crypts and stomach pits
seen in weaned and adult scid mice. The therapeutic efficacy of paromomycin
in piglets depended on the severity of the diarrheal illness. Mild to
moderate diarrhea and infection were cleared after paromomycin treatment of
piglets infected with one C. parvum isolate. However, paromomycin had no
impact on severely affected piglets infected with a second isolate,
presumably because of a rapid transit time through the gut. In contrast to
paromomycin hyperimmune bovine colostrum-immunoglobulin treatment reduced
the rate of C. parvum infection moderately in scid mice and only slightly
in piglets, again probably because of a rapid transit time through the gut
and inactivation in the stomach. It was also clear that the impact of
effective drugs against C. parvum can be detected within 5 days after the
onset of treatment in either model.
Copyright © 1994 by the American Society for Microbiology. All rights reserved.
Evaluation of an animal model system for cryptosporidiosis: therapeutic efficacy of paromomycin and hyperimmune bovine colostrum-immunoglobulin
Department of Comparative Medicine, Tufts University School of Veterinary Medicine, Grafton, Massachusetts 01536, USA.
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