Identification of antigenic epitopes of strongyloides stercoralis filariform larval antigen for immunodiagnosis of strongyloidiasis using western blot

ABSTRACT

Microscopic diagnosis of strongyloidiasis depending on detection of larvae in fecal samples is not sensitive, especially in asymptornatic patients, and development of reliable serological methods is imperative. Western blot [WB] technique showed promising results for the reactivity analysis in several parasitic infections. The objective of the present study is to identify relevant proteins of S. stercoralis filariform larvae [L3] using WB and a panel of serum samples for immunodiagnosis of strongyloidiasis. Material and S. stercoralis L3 were cultured from fecal samples of infected patients. The antigen was extracted and analyzed using SDS-PAGE. Sixty nine serum samples belonging to 3 groups of patients were analyzed and included in the study as Group I [shedding S. stercoralis larvae in feces], group II [infected with other parasites], and group III [with negative parasitological results]. Reactivity of the resulting bands of S. stercoralis L3 antigen was analyzed with the serum samples using WB technique. Thirty four immunoreactive bands were detected in the WB analysis representing recognition of proteins with molecular weight [MW] varying from 19 to 214 kDa. Immunodominant proteins of 43, 41, 36, and 23/33 kDa were recognized respectively in 39%, 35%, 70% and 60% of sera from patients with confirmed strongyloidiasis; and in 29%, 21%, 21% and 30% of sera from those infected with other parasitic infections. One band [41 kDa] gave reaction with one serum sample from group III. It was concluded that the 43, 41, 36 and 32 kDa bands could be considered important tools for the development of diagnostic techniques for strongyloidiasis