High affinity anti-Internalin B VHH antibody fragments isolated from naturally and artificially immunized repertoires.

The need for rapid and easy technologies for the detection of food-borne and environmental pathogens is essential for safeguarding the health of populations. Furthermore, distribution of tainted food and water can have consequences which can affect whole economies. Antibodies and antibody fragments have been historically used in detection platforms due to their antigen specificity and robust physicochemical properties. In this study, we report the isolation and characterization of antibody fragments from the heavy chain antibody repertoire (VHH) of Camelidae which bind with specificity and high affinity to the Listeria monocytogenes invasin, Internalin B (InlB). To the best of our knowledge, this is the first report of anti-InlB VHHs from camelids. These anti-InlB VHHs were not cross-reactive to the structurally related Listeria invasin Internalin A (InlA) and are potential reagents to be used in the development of detection and medical technologies.

Diet-induced obese rats have higher iron requirements and are more vulnerable to iron deficiency.

PURPOSE: Since obesity is associated with poorer iron status, the effects of diet-induced obesity on iron status and iron-regulatory pathways were examined. METHODS: Weanling male diet-induced obese sensitive (n = 12/diet group) and resistant (n = 12/diet group) rats were fed one of four high-fat, high-energy diets supplemented with 5 (5Fe, low), 15 (15Fe, marginal), 35 (35Fe, normal) or 70 (70Fe, high) mg iron/kg diet for 12 weeks. At the end of the study, rats in each diet group were categorised as obese (>19 %) or lean (<17 %) based on percentage body fat. RESULTS: Obese rats gained more weight, had larger total lean mass, consumed more food and showed greater feed efficiency compared with lean rats. Obese rats fed the 5Fe and 15Fe diets had poorer iron status than lean rats fed the same diet. Obese 5Fe rats had lower serum iron and more severe iron-deficiency anaemia. Obese 15Fe rats had lower mean corpuscular haemoglobin and liver iron concentrations. Hepcidin mRNA expression in liver and adipose tissue was similar for obese and lean rats. Iron concentration and content of the iron transporters divalent metal transporter 1 and ferroportin 1 in duodenal mucosa were also similar. CONCLUSIONS: Obese rats that were larger, regardless of adiposity, had higher iron requirements compared with lean rats that appeared independent of hepcidin, inflammation and intestinal iron absorption. Higher iron requirements may have resulted from larger accretion of body mass and blood volume. Greater food consumption did not compensate for the higher iron needs, indicating increased susceptibility to iron deficiency.