Systemically administered IgG anti-toxin antibodies protect the colonic mucosa during infection with Clostridium difficile in the piglet model.

The use of anti-toxin human monoclonal antibodies (HMab) as treatment for C. difficile infection has been investigated in animal models and human clinical trials as an alternative to or in combination with traditional antibiotic therapy. While HMab therapy appears to be a promising option, how systemically administered IgG antibodies protect the colonic mucosa during Clostridium difficile infection is unknown. Using the gnotobiotic piglet model of Clostridium difficile infection, we administered a mixture of anti-TcdA and anti-TcdB HMabs systemically to piglets infected with either pathogenic or non-pathogenic C. difficile strains. The HMabs were present throughout the small and large intestinal tissue of both groups, but significant HMabs were present in the lumen of the large intestines only in the pathogenic strain-infected group. Similarly, HMabs measured in the large intestine over a period of 2-4 days following antibody administration were not significantly different over time in the gut mucosa among the groups, but concentrations in the lumen of the large intestine were again consistently higher in the pathogenic strain-infected group. These results indicate that systemically administered HMab IgG reaches the gut mucosa during the course of CDI, protecting the host against systemic intoxication, and that leakage through the damaged colon likely protects the mucosa from further damage, allowing initiation of repair and recovery.

Identifying parentage using molecular markers: improving accuracy of studbook records for a captive flock of marabou storks (Leptoptilos crumeniferus).

Extra-pair copulations (EPCs) leading to extra-pair fertilization (EPF) are common in avian mating systems, despite the prevalence of observed social monogamy in many species. Colonially breeding birds are interesting species to investigate the prevalence of EPCs and EPF because they show nesting habits including close proximity of nest sites and sexual partners, which are proposed to promote alternative reproductive tactics. Endemic to Africa, the colonial marabou stork (Leptoptilos crumeniferus) is one of the most commonly held avian species in North American zoos. The aims of this study were to use genetic information to verify parentage in a population of marabou stork housed at Disney's Animal Kingdom® based on five microsatellite loci and to investigate reproductive behavior. We compared genetic analyses of parents and offspring to studbook data collected through behavioral observations of parental behavior at the nest. Using genetic analyses to reconstruct the pedigree of the marabou stork flock using the program COLONY led to improvement of studbook records by determining parentage of an individual that had previously unknown parentage, and identified one individual that had a sire that differed genetically from studbook records. An important contribution of our analyses was the identification and verification of the most likely parents for offspring hatched in this colony and improving incorrect or undocumented parentage in the studbook. Additionally, the colonial nature of this species makes it difficult to observe and understand reproductive behavior. Gaining better understanding of the mating system of a species is essential for successful breeding and captive management.