Detection of Bacillus anthracis in animal tissues using InBios active anthrax detect rapid test lateral flow immunoassay.

The Active Anthrax Detect (AAD) Rapid Test lateral flow immunoassay is a point-of-care assay that was under investigational use for detecting Bacillus anthracis capsular polypeptide (polyglutamic acid) in human blood, serum and plasma. Small sample volumes, rapid results and no refrigeration required allow for easy use in either the field or laboratory. Although the test was developed for use in suspect cases of human inhalation anthrax, its features also make it a potentially powerful tool for testing suspect animal cases. We tested animal tissue samples that were confirmed or ruled out for B. anthracis. The AAD Rapid Tests were also deployed in the field, testing animal carcasses during an anthrax outbreak in hippopotami (Hippopotamus amphibius) and Cape buffalo (Syncerus caffer) in Namibia. Evaluation of all samples showed a specificity of 82% and sensitivity of 98%. However, when the assay was used on specimens from only fresh carcasses (dead for <24 h), the specificity increased to 96%. The AAD Rapid Test is a rapid and simple screening assay, but confirmatory testing needs to be done, especially when the age of the sample (days animal has been deceased) is unknown. SIGNIFICANCE AND IMPACT OF THE STUDY: In countries where anthrax is endemic, many human outbreaks are often caused by epizootics. Earlier detection of infected animals may allow for identification of exposed people, early implementation of prevention and control methods, and ultimately lessen the number of people and animals affected. Detection of Bacillus anthracis in animal tissues using a simple, rapid and field-deployable method would allow for faster outbreak response. We evaluated a simple sample collection and processing method for use with the Active Anthrax Detect Rapid Test lateral flow immunoassay to screen dead animals for anthrax.

Relationship among function, phenotype, and specificity in primary allospecific T cell populations: identification of phenotypically identical but functionally distinct primary T cell subsets that differ in their recognition of MHC class I and class II allodeterminants.

The goal of the present study was to evaluate the relationship among function, Lyt phenotype, and MHC recognition specificity in primary allospecific T cell populations. By using Lyt-2+ and L3T4+ T cells obtained from the same responder populations, we assessed the ability of T cells of each phenotype to generate cytotoxic effector cells (CTL) and IL 2-secreting helper T cells in response to either class I or class II MHC allodeterminants. It was found that a discordance between Lyt phenotype and MHC recognition specificity does exist in primary allospecific T cells, but only in one T cell subpopulation with limited functional potential: namely, Lyt-2+ T cells with cytotoxic, but not helper, function that recognize class II MHC alloantigens. Target cell lysis by these Lyt-2+ class II-allospecific CTL was inhibited by anti-Ia monoclonal antibodies (mAb), but not anti-Lyt-2 mAb, indicating that they recognized class II MHC determinants as their "restriction" specificity and not as their "nominal" specificity even though they were Lyt-2+. A second allospecific T cell subset with limited functional potential was also identified but whose Lyt phenotype and MHC restriction specificity were not discordant: namely, an L3T4+ T cell subset with helper, but not cytotoxic, function specific for class I MHC allodeterminants presented in the context of self-Ia. Thus, the present study demonstrates that primary allospecific T cell populations contain phenotypically identical subpopulations of helper and effector cells that express fundamentally different MHC recognition specificities. Because the recognition specificities expressed by mature T cells reflect the selection pressures they encountered during their differentiation into functional competence, these findings suggest that functionally distinct but phenotypically identical T cell subsets may be selected independently of one another during ontogeny. Thus, the existence of Lyt-2+ CTL specific for class II allodeterminants can be explained by the hypothesis that the association of Lyt phenotype with MHC recognition specificity results from the process of thymic selection that these Lyt-2+ effector cells avoid.