Differentiation of Trichinella species (Trichinella spiralis/Trichinella britovi versus Trichinella pseudospiralis) using western blot

Abstract

Background: Trichinellosis is a meat-borne zoonotic disease caused by parasites of the genus Trichinella. To date, 12 taxa have been described. The identification of Trichinella species is crucial in order to identify the possible source of infection, the geographical origin of the parasite and to assess risk of infection for domestic pigs and humans. Specific identification of the etiological agent is not always feasible using direct methods since the source of infection can be untraceable. The aim of this study was to develop a diagnostic tool to infer the causative Trichinella species using western blot patterns of sera derived from infected animal and human hosts.

Methods: Sera from mice experimentally infected with Trichinella spiralis, Trichinella britovi, Trichinella pseudospiralis and Trichinella papuae were tested by western blot using homologous and heterologous crude worm extracts (CWE) and a highly sensitive detection system based on chemiluminescence. In addition, sera from pigs experimentally infected with T. spiralis, T. britovi and T. pseudospiralis and from patients with confirmed T. spiralis, T. britovi and T. pseudospiralis infections, were also included.

Results: Sera from mice infected with one Trichinella species reacted with CWE proteins from all four investigated species. Likewise, sera derived from pigs and humans infected with one Trichinella species reacted with CWE proteins from all the three investigated species. Using T. spiralis CWE, sera from T. pseudospiralis-infected hosts yielded a characteristic pattern of reactivity using Wb, which differed to that produced by T. spiralis/T. britovi- or T. papuae-infected host sera.

Conclusions: The present study suggests that western blot using T. spiralis CWE may be a useful tool to distinguish Trichinella infections caused by T. pseudospiralis from those caused by T. spiralis or T. britovi. This method may support epidemiological investigations, particularly when the source of infection is not traceable.

Keywords: Crude worm extract; Diagnosis; Epidemiology; Serology; Trichinella; Western blot.

Fig. 1

Electrophoretic protein patterns of Trichinella spiralis, T. britovi, T. pseudospiralis and T. papuae crude worm extracts by SDS-PAGE. Lanes 1–4: T. spiralis, T. britovi, T. pseudospiralis and T. papuae crude worm extracts (CWE), respectively; Lane Mw: molecular weights in kDa. Arrows show the main differences among CWE protein patterns. Red circles indicate differences in band intensity between CWE profiles of T. spiralis and T. britovi; blue box indicates differences in the protein pattern between T. pseudospiralis and encapsulated species (T. spiralis and T. britovi)

Fig. 2

Western blot (Wb) patterns, signal intensities and relative migration (Rf) values of Trichinella spp. crude worm extracts (CWE) with serum samples from mice infected with Trichinella spiralis (Lane T1), T. britovi (Lane T3), T. pseudospiralis (Lane T4) and T. papuae (Lane T10). a T. spiralis (T1) infected mouse serum; b T. britovi (T3) infected mouse serum; c T. pseudospiralis (T4) infected mouse serum; d T. papuae (T10) infected mouse serum. Comparison of Wb patterns and intensities are on the left and on the right, respectively. Lane Mw: molecular weights in kDa. Red boxes refer to the highest differences detected in the Wb patterns

Fig. 3

Western blot (Wb) patterns, signal intensities and relative migration values of Trichinella spiralis crude worm extract (CWE) with sera from infected mice. a Signal intensity and relative migration values of T. spiralis CWE with a serum sample from a T. spiralis infected mouse (b, Lane 1). b Lane Mw: molecular weights in kDa; Wb pattern of four sera from *T. spiralis (Lanes 1–4) or T. pseudospiralis (Lanes 5–8) infected mice with T. spiralis CWE. c Signal intensity of T. spiralis CWE with a serum sample from a T. pseudospiralis-infected mouse (b, Lane 8). The red box indicates the highest differences detected in the Wb patterns

Fig. 4

Western blot patterns, signal intensities and relative migration values of Trichinella spiralis crude worm extract (CWE) with sera from infected pigs. a Signal intensity and relative migration values of T. spiralis CWE with a serum sample from a T. spiralis infected pig (b, Lane 1). b Lane Mw, molecular weights in kDa, Wb of T. spiralis CWE reacting proteins with three representative serum samples from T. spiralis (Lanes 1–3) or T. pseudospiralis (Lanes 4–6) infected pigs. c Signal intensity and relative migration values of T. spiralis CWE with a serum sample from a T.pseudospiralis infected pig (b Lane 6). The red box indicates the highest differences detected in the Wb patterns

Fig. 5

Western blot (Wb) patterns, signal intensities and relative migration values of serum samples from people infected by Trichinella spiralis or T. pseudospiralis. a Signal intensity and relative migration values of T. spiralis crude worm extracts (CWE) with a serum sample from a T. spiralis infected human serum (b Lane 1). b Lane Mw, molecular weights in kDa. Wb of T. spiralis (Lane 1), T. britovi (Lane 2), T. pseudospiralis (Lane 3) or T. papuae (Lane 4) CWE with anti-T. spiralis human serum (Lanes 1–4). c Wb of T. spiralis (Lane 5), T. britovi (Lane 6), T. pseudospiralis (Lane 7) or T. papuae (Lane 8) CWE with anti-T. pseudospiralis human serum (Lanes 5–8). d Signal intensity and relative migration values of T. spiralis CWE with a serum sample from a T. pseudospiralis infected human serum (c Lane 5). The red box indicates the highest differences detected in the Wb patterns

Fig. 6

Scheme of the western blot pattern of reactivity of the Trichinella spiralis crude worm extract with T. spiralis (Lane 1) or T. pseudospiralis (Lane 2) sera from infected hosts. Lane Mw: molecular weights in kDa. The red box indicates the highest differences detected in the Wb patterns