Epitope mapping of avian influenza m2e protein: different species recognise various epitopes

Published: June 30, 2016A common approach for developing diagnostic tests for influenza virus detection is the use of mouse or rabbit monoclonal and/or polyclonal antibodies against a target antigen of the virus. However, comparative mapping of the target antigen using antibodies from different animal sources has not been evaluated before. This is important because identification of antigenic determinants of the target antigen in different species plays a central role to ensure the efficiency of a diagnostic test, such as competitive ELISA or immunohistochemistry-based tests. Interest in the matrix 2 ectodomain (M2e) protein of avian influenza virus (AIV) as a candidate for a universal vaccine and also as a marker for detection of virus infection in vaccinated animals (DIVA) is the rationale for the selection of this protein for comparative mapping evaluation. This study aimed to map the epitopes of the M2e protein of avian influenza virus H5N1 using chicken, mouse and rabbit monoclonal or monospecific antibodies. Our findings revealed that rabbit antibodies (rAbs) recognized epitope 6EVETPTRN13 of the M2e, located at the N-terminal of the protein, while mouse (mAb) and chicken antibodies (cAbs) recognized epitope 10PTRNEWECK18, located at the centre region of the protein. The findings highlighted the difference between the M2e antigenic determinants recognized by different species that emphasized the importance of comparative mapping of antibody reactivity from different animals to the same antigen, especially in the case of multi-host infectious agents such as influenza. The findings are of importance for antigenic mapping, as well as diagnostic test and vaccine development.Noor Haliza Hasan, Esmaeil Ebrahimie, Jagoda Ignjatovic, Simson Tarigan, Anne Peaston, Farhid Hemmatzade

Metabolic capacities and toxigenic potential as key drivers of Bacillus cereus ubiquity and adaptation

Bacillus cereus is ubiquitous and commonly found in a wide range of environments,including food. In this study, we analysed 114 foodborne B. cereus strains isolated mainly from starchy and dairy products in order to investigate their phenotypic diversity (API system), antimicrobial resistance and toxigenic profiles (hblA, nheA, hlyII,cereolysin O, cytK2, cytK1 and EM1 genes). All isolates were confirmed as B. cereus using 16S-23S ribosomal DNA intergenic transcribed spacers (ITS) signature. They were shown as Gram-positive, catalase and caseinase positive, haemolytic (97%), and positive for lecithin hydrolysis and motility (97 and 87 %, respectively). PCR detection of the B. cereus specific toxin genes revealed the occurrence rates of 100 % for cereolysin O, 98 % for nheA, 74 % for cytk2, 52 % for hblA, 28 % for hlyII, and the absence of cytK1. Only two strains (1.75%), isolated from intestine of boar and pheasant, carried the emetic toxin genetic determinants (ces). Antimicrobial susceptibility of isolates was tested towards 15 different antimicrobial agents. We detected susceptibility of all strains to most antibiotics, intermediate resistance to clindamycin and resistance to β lactam antibiotics with 83% of the resistant isolates producing β lactamase enzyme. This large phenotypic diversity combined with the toxigenic traits and antibiotic resistance; emphasize the high potential risk of food poisoning of B. cereus isolates. Beside, a clear correlation between the metabolic features and the origin of isolation was shown. Most of starchy isolates were able to hydrolyse starch while dairy strains were not able to produce amylases. Our overall results point out that the metabolic flexibility and toxigenic potential represent the main drivers for B. cereus ubiquity and adaptation in a given ecological nich