Development of the serological response in rabbits infected with Toxocara canis and Toxascaris leonina

Abstract

The indirect fluorescent antibody test using frozen sections of infective Toxocara canis and Toxascaris leonina eggs, and the enzyme linked immunosorbent assay using homogenized Toxocara canis embryonated egg extract and T canis excretory-secretory products as adsorbed antigens were used to determine the specificity and development of circulating antibodies in rabbits. Frozen sections were subdivided into four morphologically distinct compartments for analysis of the development of the circulating antibody response. The fluid surrounding the larva was the most reactive up to 21 days after infection, and this material was found to be predominantly excretory-secretory in nature. As the infection progressed antibodies directed against 'somatic' tissue materials increased. Cross reactions between sera from rabbits infected with T. canis eggs and Toxascaris leonina frozen sections, and rabbits infected with T. leonina eggs and Toxocara canis frozen sections occurred between both the excretory-secretory fluid and somatic components of the infective eggs. These results were substantiated using the enzyme linked immunosorbent assay. When T. canis excretory-secretory antigen was used, an earlier response (peak day 21) was detected than when using T. canis embryonated egg extract (peak day 35). However, cross reactions between T. canis excretory-secretory antigen and sera from rabbits infected with Toxascaris leonina occurred, indicating that the serodiagnosis of visceral larva migrans using Toxocara canis excretory-secretory antigen may still prove unsatisfactory when considering the role of Toxascaris as a possible causative agent.

IgG Antibody responses in mice coinfected with Toxocara canis and other helminths or protozoan parasites

“…The experimental model used in the present study, however, only managed to show crossreactivity in the case of infection with A. suum, that undoubtedly presents the closest phylogenetic relationship to the genus Toxocara 37,41 . It is possible, however, that this discrepancy is due to the fact that, in natural conditions, the hosts are subjected to situations that favor reinfection and that this is probably responsible for the greater stimulation of antibodies against this parasite.…”

In vitro production of Toxocara canis excretory-secretory (TES) antigen

“…Prior to the use of ES antigens as a diagnostic antigen, most surveys of human infection were based on tests using water soluble, somatic antigens derived from T. canis embryonated eggs, larvae or adults. Many of these somatic antigens lacked sensitivity and possessed a high degree of cross reactivity with other ascarid antigens (Girdwood et al 1978;Smith et al 1982).…”

“…ES antigens are the first mosaic of antigens to which an antibody response is detectable following infection (Smith et al 1982) and currently provided us with the most specific target antigen for serodiagnosis in human (de Savigny and Tizzard 1977;de Savigny et al 1979;Smith et al 1980;van Knapen et al 1983;Glickman et al 1985 andMagnaval et al 2001).…”

Prevalence of Toxocara-induced liver granulomas, detected by immunohistochemistry, in a series of autopsies at a Children’s Reference Hospital in Vitoria, ES, Brazil

“…The anti-Toxocara serum was elicited in rabbits after oral administration of infective T. canis eggs according to Smith et al [18]. An avidin-biotin-peroxidase kit from Sigma Chemical (St. Louis, MO) was used to stain paraffin sections according to the manufacturer's instructions.…”