Cross reactive cellular immune responses in chickens previously exposed to low pathogenic avian influenza

<p>Abstract</p> <p>Background</p> <p>Avian influenza (AI) infection in poultry can result in high morbidity and mortality, and negatively affect international trade. Because most AI vaccines used for poultry are inactivated, our knowledge of immunity against AI is based largely on humoral immune responses. In fact, little is known about cellular immunity following a primary AI infection in poultry, especially regarding cytotoxic T lymphocytes (CTL’s).</p> <p>Methods</p> <p>In these studies, major histocompatibility complex (MHC)-defined (B²/B²) chickens were infected with low pathogenic AI (LPAI) H9N2 and clinical signs of disease were monitored over a two weeks period. Splenic lymphocytes from infected and naïve birds were examined for cross reactivity against homologous and heterologous (H7N2) LPAI by ex vivo stimulation. Cellular immunity was determined by cytotoxic lysis of B²/B² infected lung target cells and proliferation of T cells following exposure to LPAI.</p> <p>Results</p> <p>Infection with H9N2 resulted in statistically significant weight loss compared to sham-infected birds. Splenic lymphocytes derived from H9N2-infected birds displayed lysis of both homologous (H9N2) and heterologous (H7N2) infected target cells, whereas lymphocytes obtained from sham-infected birds did not. T cell proliferation was determined to be highest when exposed to the homologous virus.</p> <p>Conclusions</p> <p>Taken together these data extend the findings that cellular immunity, including CTL’s, is cross reactive against heterologous isolates of AI and contribute to protection following infection.</p

Identifying Research Gaps for the Role of the Environment in Transmission of Antimicrobial-Resistant Escherichia coli in Cow-Calf Operations in North America: A Scoping Review Protocol

Scoping ReviewEscherichia coli (E.coli) is a gram negative rod-shaped bacteria which is found in the intestines of people, animals and in the environment. E.coli is also found in food and untreated water. Antimicrobial use in animal production against bacteria such as E. coli is essential for maintaining animal health. However, increased antimicrobial use poses the risk of contributing to the problem of antimicrobial resistance. Antimicrobial resistance occurs when microorganisms selectively develop mechanisms to protect themselves from the effects of antimicrobial compounds. Antimicrobial resistance is a One Health concern as it impacts animal, human and ecosystem health. In North America, the term cow-calf production refers to cattle raised exclusively or largely on pasture, having a grass- or hay-based diet, and which may consume a low amount of concentrate diet, producing an annual crop of calves. The calves are intended for beef production and are usually backgrounded on pasture or backgrounding lots and then finished with a high concentrate diet in feedlots. Although this literature review is not restricted to North America, information retrieved will be discussed in relation to cow-calf operations in North America. For the purpose of this scoping review, the term “environment” will refer to environmental features such as: manure, wildlife, soil, insects, and water sources. By including these search terms, the scoping review will identify environmental reservoirs that have been shown to impact the transmission of antimicrobial-resistant E. coli in cow-calf operations. Our aim is to conduct a scoping review of the evidence regarding the role of the environment in the transmission and maintenance of antimicrobial-resistant E. coli within cow-calf operations. This study will identify gaps in knowledge regarding the reservoirs and transmission of antimicrobial-resistant E. coli in cow-calf operations (2). Because the mechanisms of maintenance and transmission of antimicrobial resistance in the environment are obscure, this scoping review will aid in determining the quantity and nature of information that presently exists in this field, and aid in identifying directions for future research (3). The review will be conducted between July 1, 2021 and August 31, 2021.Alberta Innovates - Research Gran

Genetic characterization of AmpC and extended-spectrum beta-lactamase (ESBL) phenotypes in Escherichia coli and Salmonella from Alberta poultry

Horizontal gene transfer is an important mechanism which facilitates bacterial populations in overcoming antimicrobial treatment. In this study, a total of 120 Escherichia coli and 62 Salmonella enterica subsp. enterica isolates were isolated from broiler chicken farms in Alberta. Fourteen serovars were identified among Salmonella isolates. Thirty one percent of E. coli isolates (37/120) were multiclass drug resistant (resistant to ≥ 3 drug classes), while only about 16% of Salmonella isolates (10/62) were multiclass drug resistant. Among those, eight E. coli isolates had an AmpC-type phenotype, and one Salmonella isolate had an extended-spectrum beta-lactamase (ESBL)-type beta-lactamase phenotype. We identified both AmpC-type (blaCMY-2) and ESBL-type (blaTEM) genes in both E. coli and Salmonella isolates. Plasmids from eight of nine E. coli and Salmonella isolates were transferred to recipient strain E. coli J53 through conjugation. Transferable plasmids in the eight E. coli and Salmonella isolates were also transferred into a lab-made sodium azide-resistant Salmonella recipient through conjugation. The class 1 integrase gene, int1, was detected on plasmids from two E. coli isolates. Further investigation of class 1 integron cassette regions revealed the presence of an aadA gene encoding streptomycin 3’’-adenylyltransferase, an aadA1a/aadA2 gene encoding aminoglycoside 3’’-O-adenyltransferase, and a putative adenylyltransferase gene. This study provides some insight into potential horizontal gene transfer events of antimicrobial resistance genes between E. coli and Salmonella in broiler chicken production.publishedVersio

Diversity of Antimicrobial Resistance Phenotypes in Salmonella Isolated from Commercial Poultry Farms

Salmonella remains the leading cause of foodborne illness in the United States, and the dissemination of drug-resistant Salmonellae through the food chain has important implications for treatment failure of salmonellosis. We investigated the ecology of Salmonella in integrated broiler production in order to understand the flow of antibiotic susceptible and resistant strains within this system. Data were analyzed from a retrospective study focused on antimicrobial resistant Salmonella recovered from commercial broiler chicken farms conducted during the initial years of the US FDA’s foray into retail meat surveillance by the National Antimicrobial Resistance Monitoring System (NARMS). Sixty-three percentage of Salmonella were pan-susceptible to a panel of 19 antimicrobials used by the NARMS program. Twenty-five antimicrobial resistance phenotypes were observed in Salmonella isolated from two broiler chicken farms. However, Salmonella displaying resistance to streptomycin, alone, and in combination with other antibiotics was the most prevalent (36.3%) antimicrobial resistance phenotype observed. Resistance to streptomycin and sulfadimethoxine appeared to be linked to the transposon, Tn21. Combinations of resistance against streptomycin, gentamicin, sulfadimethoxine, trimethoprim, and tetracycline were observed for a variety of Salmonella enterica serovars and genetic types as defined by pulsed-field gel electrophoresis. There were within and between farm differences in the antibiotic susceptibilities of Salmonella and some of these differences were linked to specific serovars. However, farm differences were not linked to antibiotic usage. Analysis of the temporal and spatial distribution of the endemic Salmonella serovars on these farms suggests that preventing vertical transmission of antibiotic-resistant Salmonella would reduce carcass contamination with antibiotic-resistant Salmonella and subsequently human risk exposure