Characterization of experimental Cryptosporidium parvum infection in IFN-γ knockout mice

XIANGDONG YOU a1 and J. R. MEAD a1a2c1
a1 Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
a2 Georgia VA Research Center on AIDS and HIV Infection, Veterans Affairs Medical Center, Decatur, GA 30033, USA


Severe cryptosporidial infections were produced in gamma interferon (IFN-γ) knockout mice. Mean oocyst shedding increased from 332 to 30717 oocysts/100 μl of faecal suspension between day 4 and 9 after administration of 1×105 oocysts/mouse. No significant differences in oocyst shedding were observed in mice after being inoculated with 1×105, 1×104 or 1×103 oocysts/mouse (P>0·05). Infected mouse weights decreased an average 3–4 g before death or euthanization. Histological studies revealed heavy parasite colonization in small intestinal epithelium (approximately 250 organisms/high-power field at ×400). Mesenteric lymph nodes in infected mice were markedly enlarged compared to controls (P<0·05). Both CD4+ and CD8+ T cell populations increased in spleens of infected mice while the B cell population increased in mesenteric lymph nodes from infected mice. No significant proliferation was observed when pooled lymphocytes from infected mice were exposed to C. parvum antigens in vitro. Addition of recombinant mouse IFN-γ did not restore antigen responsiveness. While lymphoproliferative responses to specific antigen were not significant in the short period following infection, this mouse model provides unique features to study the characteristics of acute infection and the immune response against C. parvum.

(Received March 4 1998)
(Revised June 10 1998)
(Accepted June 11 1998)

Key Words: Cryptosporidium parvum; gamma interferon; knockout mice.

c1 Corresponding author: VA Medical Center Research 151, 1670 Clairmont Road, Decatur, GA 30033, USA. Tel: +1 404 321 6111. X2545. Fax: +1 404 728 7780. E-mail: