Abstract
Background: Locusts as model systems are widely used in many biological
laboratories worldwide. Occupational exposure to locusts induces a high
prevalence of allergic sensitization. However, knowledge on occupational
locust allergens remains unclear. This study aimed to identify a novel
allergen from locusts that causes occupational allergies. Methods: We
conducted a 20-year retrospective survey of 94 persons using
questionnaires and a cross-sectional survey of 57 persons using
questionnaires and immunological tests for occupational allergies in
long-term locust laboratories. We identified the major allergens by
immunoblotting and analysed them by LC-MS/MS. The allergenicity of the
major allergen proteins was assessed by specific IgE (sIgE) detection,
immunoblotting and ELISA inhibition assays. Results: The retrospective
survey indicated that the frequency of occupational allergies was
relatively low (13.8%), while the cross-sectional survey showed a
higher frequency (40.4%). The symptoms in most allergic males were
allergic rhinitis and asthma, while females showed higher prevalence of
atopic dermatitis. Occupational exposure for 2-3 h per day or continuing
one and half years obviously increased the allergy risk. We identified
the hexamerin-2 protein as a major allergen in locusts. Purified
hexamerin-2 protein achieved approximately 60% serum IgE reactivity
with locust protein extract. The potential for cross-reactivity with
cockroaches was indicated by sequence alignment of the hexamerin-2
protein and allergens of cockroaches. Conclusion: Occupational exposure
is an important risk factor for locust allergy. The hexamerin-2 protein
of locusts as a major allergen in occupational allergy was identified
for the first time.