Prebiotic inulin supplementation modulates the immune response and restores gut morphology in Giardia duodenalis-infected malnourished mice.

Malnutrition induces a state of growth retardation and immunologic depression, enhancing the host susceptibility to various infections. In the present study, it was observed that prebiotic supplementation either prior or simultaneously with Giardia infection in malnourished mice significantly reduced the severity of giardiasis and increased the body and small intestine mass, along with increased lactobacilli counts in faeces compared with malnourished-Giardia-infected mice. More specifically, prebiotic supplementation significantly increased the levels of anti-giardial IgG and IgA antibodies and anti-inflammatory cytokines IL-6 and IL-10 and reduced the pro-inflammatory cytokine TNF-α, along with increased levels of nitric oxide in both the serum and intestinal fluid of malnourished-prebiotic-Giardia-infected mice compared with malnourished-Giardia-infected mice. Histopathology and scanning electron microscopy of the small intestine also revealed less cellular and mucosal damage in the microvilli of prebiotic-supplemented malnourished-Giardia-infected mice compared with severely damaged mummified and blunted villi of malnourished-Giardia-infected mice. This is the first study to report that prebiotic supplementation modulated the gut morphology and improved the immune status even in malnourished-Giardia-infected mice.

Passive immunity and serological immune response in dairy calves associated with natural Giardia duodenalis infections.

In a previous study, Giardia infection patterns were studied in newborn dairy calves over a 4-month period. Chronic Giardia infections were observed in all calves with initial cyst excretion occurring at approximately 1 month of age. In the work presented here, the passive immunity and serological immune response associated with these Giardia infections were examined. Colostrum and milk samples were collected from the dams of these calves, and monthly serum samples were collected from each calf. The colostrum, milk and sera samples were analyzed by ELISA and Western blot for the presence of anti-Giardia IgG antibodies. In addition, the in vitro anti-Giardia activity of milk and colostrum was examined using a miniculture adherence assay. When examined by ELISA, mean anti-Giardia antibody titres were found to be significantly higher in colostrum compared to milk. The monthly mean serum antibody titres in the calves were not found to differ significantly at any time point during the study. Western blot analysis revealed that colostrum from the dams reacted strongly with many different Giardia antigens between 205 and 7.5kDa, while milk reacted with few antigens in the same size range. Sera collected from the calves when 30 and 60 days of age reacted with few Giardia antigens, but as the calves aged, IgG antibodies in their sera began to react with antigens of 21, 50, 65, 73 and 79kDa. The miniculture adherence assay demonstrated that colostrum had significantly more anti-Giardia activity in vitro compared to milk. These results suggest that the calves in this dairy did not mount a significant humoral immune response against Giardia following infection. However, colostrum contained a high level of anti-Giardia antibodies and exhibited anti-Giardia activity in vitro. Therefore, colostrum may have the potential to provide initial protection against Giardia infections in calves, but the lack of a strong, specific humoral immune response by these calves could account for the high prevalence and chronic duration of the infections.

Further studies on fecal parasites in antiquity.

This is a continuation study of the survival of antigenic material over the centuries using mummified human remains from the Andean area of South America. The fluorescent antibody kit from Meridian Diagnostics (Cincinnati, OH) was used to identify some Cryptosporidium species and Giardia species found in feces from the intestines of mummies 500 to 3,000 years old. The specimens that were positive by direct visualization using fluorescent antibody were then tested with an enzyme-linked immunosorbent assay reaction using a Meridian kit just released on the market. Since all of the feces used were formed, it would seem that the organisms found were from carriers rather than active cases of disease. Similar fecal specimens were shown to harbor antigens from Helicobacter pylori almost 3,000 years old.

Modification of RPMI 1640 for use in vitro immunological studies of host-parasite interactions in giardiasis.

Incubation of trophozoites for 6 h in RPMI 1640 affected the viability of the parasite; however, RPMI 1640 supplemented with L-cysteine did not affect trophozoite viability, ability to grow when transferred to fresh TYI-S-33, or ability to infect gerbils. Similarly, incubation of murine spleen cells in modified medium did not affect the viability of the cells or proliferative responses to mitogens. RPMI 1640 supplemented with 11.4 mM L-cysteine is a suitable maintenance medium for in vitro studies in immunoparasitology because it maintains viability as well as some of the physiological functions of both trophozoites and lymphocytes.