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Allergic Responses Induced by a Fungal Biopesticide Metarhizium anisopliae and House Dust Mite are Compared in a Mouse Model
WARD, M. D., Y. CHUNG, L. B. COPELAND, AND D. L. DOERFLER. Allergic Responses Induced by a Fungal Biopesticide Metarhizium anisopliae and House Dust Mite are Compared in a Mouse Model. TOXICOLOGY. Elsevier Science Ltd, New York, NY, 2011(ID360805):1-13, (2011).
The toxicity associated with many chemical pesticides has provided the impetus to develop biological agents, either native or genetically engineered, for pest control. Microorganisms (bacteria, viruses, and fungi) have been identified or developed for release in the environment to address such diverse problems as pest control, frost damage, soil supplements and pollution. Generally the research has focused on the potential pathogenicity and toxicity of these agents. However, allergenicity is ofparticular concern because, in addition to the medical and economic impact on the general population, about 75% of asthma cases are triggered by allergens. Morbidity and mortality due to asthma have increased considerably over the past 30 years for reasons that are not entirely clear, but could in part be related to the environment. Therefore, a need exists to determine the risk of allergic reactions associated with exposure to bio-pesticides by development of models for screening and assessing these allergic reactions. Metarhizium anisopliae, a fungal biopesticide, has been used for agricultural pest control for over a century because of its pathogenicity for a broad range of insect hosts. Not only is M. anisopliae licensed in the United States for indoor use in cockroach control but recent reports have identified M anisopliae as a potentially useful pesticide to combat malaria. Anecdotal information as well as limited clinical data has suggested that some individuals exposed occupationally to M anisopliae have become sensitized.
Biopesticides can be effective in controlling their target pest. However, research regarding mammalian health impacts of these agents has focused on toxicity and pathogenicity, with limited research regarding allergenicity and asthma development. We compared the ability of fungal biopesticide Metarhizium anisopliae (MACA) and house dust mite (HDM) extracts to induce allergic responses in BALB/c mice. The extracts were administered by intratracheal aspiration at doubling doses (2.5-80 ug protein) 4X over a four-week period. Three days after the last exposure serum and bronchoalveolar lavage fluid (BALF) were collected. The extracts' relative allergenicity was evaluated based on response robustness at the lowest significant dose response compared to control (0 ug), MACA induced the most robust response at the lowest dose for BALF lymphocyte cell count as well as serum total IgE. In the antigen-specific IgE assay, a similar dose of both MACA and HDM was required to achieve the same response level. Our data suggest a threshold dose of MACA for the allergy induction and that M. anisopliae may be similar to HDM in allergy induction potential.