Goat milk with different S2-casein content: analysis of allergenic potency by REAST-inhibition assay

In goat at CSN1S2 locus, seven alleles have been observed, characterized by different levels of expression, and, in particular, a null allele CSN1S2O that significantly influences protein composition of milk. In a local goat breed reared in the North East of Sicily, “Argentata dell’Etna”, the combined use of electrophoretic milk analysis (SDS-PAGE) and 11th exon genomic analysis (PCR-RFLP) made it possible to identify three genotypes respectively normal (CSN1S2NN), heterozygote for the null allele (CSN1S2NO) and homozygote for the null allele (CSN1S2OO). In 214 “Argentata dell’Etna” goats, CSN1S2O allele has shown a frequency of 0.033. An immunological test, REAST-inhibition assay (REAST, reverse enzyme allergo sorbent test), was carried out on three lyophilized milk samples (casein and seroprotein fractions) produced by goats with different genotypes at CSN1S2 locus, in order to assess their allergenic potency. By comparing the C50, the casein fraction CSN1S2NN turned out to be the most allergenic, followed by the fraction CSN1S2OO with 60% potency compared to the first one, while the fraction CSN1S2NO presented 54% potency compared to the first one. © 2003 Elsevier B.V. All rights reserved.