Background: Concentrations of Alt a1, a major allergen from Alternaria alternata extracts, exhibit significant batch-to-batch variability. This variability may result from basic strain-related genetic differences or from environmental influences such as growth conditions or extraction methods.
Objective: The objective of this work is to determine if strain-to-strain allergen variability in Alternaria alternata, Alt a1 allergen occurs at the nucleic acid level.
Methods: We compared the content of mRNA for a segment known to contain sequence coding for the reported N-termini of this allergen in eight strains of Alternaria obtained from three individual sources grown under identical conditions. RNA was extracted from rapidly growing mycelia and analyzed by northern blot analysis for the content of a specific segment containing sequence for the Alt a1 allergen. Blots were also analyzed for the content of a specific 5.8S rRNA segment.
Results: The size of the mRNA for this protein was about 700 bases. Sequence for the specific segment was found in all of the eight strains tested. When normalized for extraction variabilities using the content of 5.8S rRNA, the calculated concentrations of Alt a1 mRNA of seven of the eight strains were similar.
Conclusions: The results of these experiments suggest that this Alt a1 related allergen sequence is found in many strains of Alternaria and that variabilities in allergen protein content noted previously result from posttranslational events.