RORγt + Treg to Th17 ratios correlate with susceptibility to Giardia infection

Funder: Fundacion Alfonso Martin EscuderoFunder: RCUK | Biotechnology and Biological Sciences Research Council (BBSRC); doi: https://doi.org/10.13039/501100000268Funder: Isaac Newton Trust; doi: https://doi.org/10.13039/501100004815Abstract: Infections with Giardia are among the most common causes of food and water-borne diarrheal disease worldwide. Here, we investigated Th17, Treg and IgA responses, and alterations in gut microbiota in two mouse lines with varying susceptibility to Giardia muris infection. Infected BALB/c mice shed significantly more cysts compared with C57BL/6 mice. Impaired control of infection in BALB/c mice was associated with lower Th17 activity and lower IgA levels compared with C57BL/6 mice. The limited metabolic activity, proliferation and cytokine production of Th17 cells in BALB/c mice was associated with higher proportions of intestinal Foxp3+RORγt+ regulatory T cells and BALB/c mice developed increased RORγt+ Treg:Th17 ratios in response to G. muris infection. Furthermore, G. muris colonization led to a significantly reduced evenness in the gut microbial communities of BALB/c mice. Our data indicate that differential susceptibility to Giardia infections may be related to RORγt+ Treg controlling Th17 activity and that changes in the microbiota composition upon Giardia infection partially depend on the host background

Giardia duodenalis and Cryptosporidium spp. in a veterinary college bovine teaching herd

In a preliminary study, we commonly identified Giardia duodenalis in adult dairy cattle from a veterinary college teaching herd. Therefore, the present study was carried out in order to better understand the potential of adult cattle to act as a source for G.duodenalis infections for students and staff at the veterinary college. Fecal samples were collected bi-weekly from this herd of adult cattle (n = 30) over an 8-month period to determine the prevalence of G. duodenalis and Cryptosporidium spp. within the herd. Nested PCR followed by DNA sequencing was then performed on a subset of positive samples in order to better understand the zoonotic potential of these infections. Every cow was sampled between 11 and 18 times, depending on the date the animal joined the teaching herd. In total, 507 fecal samples were collected from 30 different cows and examined for cysts and oocysts using epifluorescence microscopy. G. duodenalis prevalence during the course of the study ranged from 37% (11/30) to 64% (18/28), with a mean of 49%. Cumulative G. duodenalis prevalence was 73% (22/30). Zoonotic G. duodenalis assemblage A genotype was identified in 43% (6/14) of the G. duodenalis-positive samples on which PCR and genetic sequencing were successfully performed. G. duodenalis assemblage E was identified in 57% (8/14) of these samples. Cryptosporidium spp. oocysts were not detected in the feces of any cows during the study period. The presence of the zoonotic G. duodenalis assemblage A in 43% of the sequenced samples indicates that there is a potential risk of infection for students and staff at this research and teaching facility, although the roles of cows as sources of giardiasis in humans remain uncertain. Furthermore, due to the large amount of feces they produce, adult cattle may serve as important sources for G. duodenalis infections in young cattle, or other animals in the facility, despite relatively low numbers of cysts excreted per gram of feces. In contrast, the results of this study indicate that this herd posed a negligible risk of transmitting Cryptosporidium parvum infections to humans.Fabienne D. Uehlinger, Herman W. Barkema, Brent R. Dixon, Tatjana Coklin and Ryan M. O’Handle

Prevalence and molecular characterization of Cryptosporidium spp. in dairy calves from 11 farms in Prince Edward Island, Canada

Cryptosporidium spp. are common intestinal protozoan parasites that infect a wide range of hosts, including humans and livestock, worldwide. The objective of this study was to determine the prevalence of Cryptosporidium spp. in dairy calves in Prince Edward Island, Canada, and the potential for transmission of this parasite between dairy calves and humans. Fecal samples were collected from 183 dairy calves from 11 farms in Prince Edward Island. The prevalence of Cryptosporidium spp. infections in these animals was determined by examining for the presence of oocysts in the fecal samples, using immunofluorescence microscopy. Molecular characterization was done using a nested-PCR protocol to amplify fragments of the Cryptosporidium heat-shock protein 70 gene, followed by DNA sequencing. Ten calves (6.2%), representing 4 out of 11 farms tested, were positive for Cryptosporidium spp. DNA sequence analysis on five PCR positive samples demonstrated that Cryptosporidium parvum was the only species present in the calves tested, suggesting that there is a potential risk of zoonotic transmission between dairy calves and humans in this region