Mary M. Patterson

Persistent infection of rhesus monkeys with ‘Helicobacter macacae’ and its isolation from an animal with intestinal adenocarcinoma

A novel helicobacter, ‘Helicobacter macacae’, was previously isolated from a colony of rhesus and cynomolgus monkeys in which diarrhoea from chronic idiopathic colitis was enzootic. A survey performed in a second colony of rhesus monkeys without a history of chronic diarrhoea determined that 57 % were faecal-culture positive for Helicobacter species. Ten years after the survey, one of the animals from which ‘H. macacae’ had been isolated, a 23-year-old, intact male rhesus monkey (Macaca mulatta), presented with partial inappetence and progressive weight loss. Subsequent evaluation of the monkey revealed anaemia, hypoproteinaemia, hypoalbuminaemia and a palpable abdominal mass. Contrast radiography suggested partial intestinal obstruction. The animal was euthanized and a diagnosis was made of intestinal adenocarcinoma of the ileocaecocolic junction with metastasis to regional lymph nodes and liver. Microaerobic culture of caecal tissue yielded a helicobacter organism identified as ‘H. macacae’ by 16S rRNA gene sequencing – the same species of bacteria isolated 10 years previously. The liver, small intestine and colon were also positive by PCR for Helicobacter species. Intestinal adenocarcinoma is the most common malignancy of aged macaques. Faeces or caecal tissue from five out of five monkeys that remained from the original cohort and that were colonized with ‘H. macacae’ in the initial survey were positive for the organism. The apparent persistence of ‘H. macacae’ in these animals, the isolation of the bacterium from animals with colitis and the recognition of the importance of inflammation in carcinogenesis raise the possibility of an aetiological role in the genesis of intestinal adenocarcinoma in aged rhesus monkeys.

Experimental Helicobacter marmotae infection in A/J mice causes enterohepatic disease

Helicobacter marmotae has been identified in the inflamed livers of Eastern woodchucks (Marmota monax) infected with woodchuck hepatitis virus (WHV), as well as from the livers of WHV-negative woodchucks. Because the majority of WHV-positive woodchucks with hepatic tumours were culture or PCR positive for this helicobacter, and WHV-negative woodchucks with H. marmotae had hepatitis, the bacterium may have a role in tumour promotion related to chronic inflammation. In this study, the type strain of H. marmotae was inoculated intraperitoneally into 48 male and female A/J mice, a strain noted to be susceptible to Helicobacter hepaticus-induced liver tumours. Sixteen mice served as mock-dosed controls. At 6, 12 and 18 months post-inoculation (p.i.), there were statistically significant (P<0.05) differences in mean inflammation scores for the caecum and proximal colon between experimentally infected and control mice. Differences in hepatic inflammation were significant (P<0.05) at 6 and 12 months p.i. between the two groups but not at the 18 month time point. Two infected male mice had livers with severe hepatitis, and the liver samples were culture positive for H. marmotae. Serum IgG levels in the mice dosed with H. marmotae were elevated for the duration of the study. These results demonstrate that the woodchuck helicobacter can successfully colonize mice and cause enterohepatic disease. In the future, a mouse-adapted strain of H. marmotae could be selected to maximize colonization and lesion development. Such a woodchuck helicobacter-infected mouse model could be used to dissect potential mechanisms of microbial co-carcinogenesis involved in tumour development in woodchucks with WHV and in humans with hepatitis B virus.

Characterization of cytotoxic necrotizing factor 1-producing Escherichia coli strains from faeces of healthy macaques

Twenty-five (27 %) of 92 clinically normal macaques were found to have beta-haemolytic Escherichia coli isolated from their faeces. Five of six isolates chosen for further characterization had multiple antibiotic resistance and were PCR-positive for cytotoxic necrotizing factor 1 (cnf1) with a demonstrated cytopathic effect in vitro. By repetitive element sequence-based PCR genotyping, genetic similarity was established for selected isolates. We believe this to be the first report of E. coli strains producing CNF1 in non-human primates.

Zebra Finches in Biomedical Research

Zebra finches (Taenopygia guttata, formerly Poephila guttata) are small, colorful songbirds that have been favored by bird fanciers since the nineteenth century. In captivity, zebra finches are prolific breeders and robust ‘easy keepers’; these characteristics, along with a diurnal activity pattern and the singing prowess of males, makes them an attractive model for biomedical researchers. Their increasing popularity resides especially in the fields of neurobiology, with a majority of investigations in the United States focusing on male vocal development, and behavior, such as the basis for mate preference and aggression. However, many other research applications, as well as the production of transgenic birds, have also been pursued. The zebra finch genome is the second avian species to be sequenced (Warren et al., 2010), after that of the chicken (Gallus gallus domesticus). Importantly, a high-resolution digital atlas of the zebra finch brain was recently published (Karten et al., 2013) and detailed; current protocols for using zebra finches in research can be accessed online (Cold Spring Harbor Press, 2014). One review article determined there were considerably more articles about zebra finches in 2008 relative to other passerine species (Bateson and Feenders, 2010), while a tally of PubMed entries for the subject ‘zebra finch’ reveals a steady annual increase in publications that started to escalate during the 1980s.