- D3.493 - Identification of Two IgE-Reactive Proteins in Planococcus citri Larvae: A Novel Case of Occupational Respiratory Allergy in a Pest-Control Laboratory Worker

Occupational allergy to insects is increasingly recognized among workers involved in pest-control, agriculture and food production. However, no allergens have been characterized to date in Planococcus citri (cotonet), a common citrus pest. We report the first documented case of respiratory allergy to P. citri larvae, supported by protein-level evidence using IgE–Western blot.

A 36-year-old laboratory worker responsible for routine manipulation of P. citri larvae developed work-related rhinitis and asthma that resolved during holidays. Protein extracts prepared from patient-provided larvae underwent homogenization, PBS extraction, sequential vacuum filtration, three dialysis cycles (3.5 kDa cutoff), lyophilization and Bradford quantification. SDS-PAGE and IgE–Western blot were performed under reducing and non-reducing conditions using the patient’s serum.

The SDS-PAGE demonstrated a reproducible protein profile in both reducing and non-reducing conditions. The IgE–Western blot revealed two clear IgE-reactive bands: one around ~20 kDa and another, more intense, around ~11 kDa. These bands were consistently detected across conditions, confirming the presence of at least two heat-stable allergens within P. citri larvae. No previously described allergens exist for this species, and no equivalent molecular weights are reported for homologous insect allergens. The pattern strongly suggests primary sensitization to larval proteins acquired through occupational exposure, aligning with published evidence showing high rates of sensitization among workers regularly handling edible or pest insects.

This case represents the first molecularly confirmed occupational allergy to Planococcus citri larvae, identifying two candidate allergens of approximately 20 kDa and 11 kDa. The findings underscore that pest-control laboratory environments can facilitate sensitization due to repeated exposure to insect proteins. Further characterization of these bands is warranted to establish their allergenic identity and evaluate their potential relevance for other exposed workers