Preliminary study of the presence of antibodies against excretory-secretory antigens from protoscoleces of Echinococcus granulosus in dogs with intestinal echinococcosis

Abstract

The aim of the present study was to analyze the antibody response against excretory-secretory antigens (ES-Ag) from Echinococcus granulosus protoscoleces, using sera from dogs infected with E. granulosus and other helminths. 65, 61, 54, and 45-46 ES-Ag were obtained from the first 50 h maintenance of protoscoleces in vitro. Immunochemical characterization was performed by immunoblotting with sera from dogs naturally infected with E. granulosus (n = 12), sera from dogs infected with helminths other than E. granulosus (n = 30), and helminth-free dog sera (n = 20). These findings were compared to those obtained from a somatic extract of protoscoleces (S-Ag). ES-Ag only showed four cross-reacting proteins of kDa. Antigens with apparent masses of 89 and 50 kDa in ES-Ag and of 130 and 67 kDa in S-Ag were identified by sera of dogs infected with E. granulosus only, whereas a protein of 41-43 kDa was recognised by the majority of the sera from dogs with non-echinococcal infection. Employing ELISA to study the same sera, S-Ag revealed higher immunoreactivity than ES-Ag, but also showed higher cross-reactivity levels when sera from dogs with non-echinococcal infection were assayed in immunoblotting.Key words: Echinococcus granulosus -excretory-secretory antigens -protoscoleces -intestinal echinococcosisparasite antigensCystic hydatid disease in man is a zoonosis caused by infection with the larval stage of the dog tapeworm Echinococcus granulosus. The adult worm lives in the small intestine of dogs and other canids, in intimate contact with the intestinal epithelium. Parasite eggs (the infective stage for the intermediate host) are excreted in faeces, and may thus contaminate soil, grass and water. Detection of E. granulosus adults in dogs is very important in order to evaluate its prevalence and to develop surveillance and control programmes for hydatidosis/echinococcosis (WHO 2001). Diagnosis of taeniid cestode infections in dogs can be carried out using arecoline hydrobromide, but this technique has a highly variable sensitivity, is time consuming and some dogs suffer undesired side-effects (Wachira et al. 1990). Coprological exams, however, have low sensitivity since excretion of the eggs occurs sporadically. Furthermore, the eggs of taeniid cestodes are morphologically indistinguishable by light microscopy.In an attempt to improve the sensitivity of E. granulosus diagnostics, different serological tests have been developed, mainly based on the detection of specific IgG antibodies against the adult parasite. Somatic extracts of protoscoleces (S-Ag) are the most commonly used antigenic source. However, ELISA results showed highly variable sensitivities, ranging from 40 to 90% (Jenkins et al. 1990, Gasser et al. 1992, 1993, 1994. These studies also demonstrated that 25-60% of the sera from dogs infected with E. granulosus did not show significant levels of specific antibody (Jenkins et al. 1990, Gasser et al. 1994, and that cross-reactivity with other parasite species may occur (Gasser et al. 1988).During recent yea...

Diagnosis of Oesophagostomum columbianum infection in goat by indirect enzyme linked immunosorbent assay

“…Two false negative results in the present assay might be due to low worm burden (9 -20) or poor immune response of the host (Gasser et al, 1994). Besides, host nutritional status (Jenkins et al, 1991;Gasser et al, 1992) and physiological and environmental factors like reinfection or coinfection with other parasites (Carmena et al, 2005) might also have an impact on the antibody levels. False positive result of the assay with postmortem negative samples might be due to the persistence of antibodies to the past infection, which might have been eliminated by anthelmintic medication.…”

“…False positive result is probably due to cross reactivity of O. columbianum with other helminths. Cross reactivity amongst different helminths is a common and limiting factor in the development of serological tests against helminth infection (Philipp & Rumjaneck 1984;Cuquerella et al, 1994;Molina et al, 1999). The short comings of antibody ELISA in the diagnosis of helminth infections would best be overcome using antigen detection ELISA.…”

Serological diagnosis of cystic echinococcosis in cattle

“…Unfortunately, very little information is available about using this type of antigen for diagnostic purposes. The results related to the detection of antibodies in the blood of infected dogs against ES-Ag of in vitro reared protoscoleces were described (Carmena et al 2005). ES-Ag obtained from the first 50 h maintenance of protoscoleces in culture medium was also tested for immunodiagnosis of human CE (Carmena et al 2004) and the immune responses of Balb/c mice to the adult tapeworm antigens cultured in vitro were also investigated (Rahimi et al 2011).…”

“…S-Ag of protoscoleces, isolated from cattle hepatic hydatid cysts, was obtained according to the method described in Carmena et al (2005). S-Ag of two trematode species, O. felineus and/or Metorchis bilis (Braun, 1790) (both Opisthorchiidae), was prepared as previously described (Borovikov et al 2010).…”

“…However, to date the value of proteins of protoscoleces and/or its individual components devoid of host antigens for diagnosis of CE in cattle has not been explored. Moreover, serological diagnosis of CE in herbivores is difficult because the causative agent of cysticercosis cysticercus tenuicollis (metacestode of Taenia hydatigena Pallas, 1766) share antigenic determinants with the protoscoleces of E. granulosus (see Carmena et al 2005, Morel et al 2013, Bulashev et al 2016a.…”