Cytokine response and outcome of infection depends on the infective dose of parasites in experimental infection by Echinococcus granulosus

Abstract

We here analysed whether the cytokine responses in early and late experimental infection with Echinococcus granulosus depend on the dose of parasites to which the host is exposed. To this purpose Balb/c mice were inoculated intraperitoneally (i.p.) with either 500 or 2000 protoscoleces. Splenocytes of mice were obtained at days 3, 7, 14 and 21 and also on week 37 post-infection and cultured in vitro with protoscolex antigens. Type-1 and type-2 cytokines were analysed in supernatants by ELISA. Results showed that the inoculation of 500 protoscoleces induced an early type-0 and a late type-2 cytokine response, whereas the inoculation of 2000 protoscoleces induced an early type-2 and a late type-0 cytokine response. Parasite growth was lower in the group inoculated with the low infective dose. These results indicate that the cytokine response during the infection by the helminth E. granulosus depends on the dose of parasites to which the host has been exposed.

Humoral and cytokine response during protection of mice against secondary hydatidosis caused by Echinococcus granulosus

“…This is inconsistent with observations made earlier that showed a significant increase in all IgG subclasses with the dominance of IgG1 (Haralabidis et al 1995). Concurrent analysis of cytokines indicated the early development of Th2, which is further polarized into Th1 at the time of cyst development at 20-28 days post-inoculation (Dematteis et al 2003). All in all, the present study reinforces earlier findings that a Th2 response is generated at the time of inoculation and continues until the time of cyst development about 4 weeks post-infection .…”

Efficiency Evaluation of Immunization Protocol with Echinococcus Granulosus Antigen B (Agb)

“…Humoral and cellular responses characterized by elevation in some serum antibodies and cytokines [14,15]. Present data indiated that immunized rabbits showed elevated IgG and IL-10 level and decreased IFN-γ level in comparing with control group after two months of immunization with AgB.…”

Immune defence, parasite evasion strategies and their relevance for ‘macroscopic phenomena’ such as virulence

“…For example, a dose of only 100-200 influenza viruses per litre of air infected virtually all experimental mice and the dose-infection relationship increased very steeply before that point (Schulman 1967). Infection by low doses (dozens or a few hundreds of infecting cells) and/or rapidly saturating dose curves were also found with experimental exposures to other viruses in mice (Diamond et al 2003;Tibbetts et al 2003), pigs (Billinis et al 2004;Hermann et al 2005) or birds (Reisen et al 2004); and similarly with mice exposed to helminths (Dematteis et al 2003) or humans experimentally infected by the protozoan parasite Cryptosporidium parvum ( Teunis et al 2002a,b). Remarkably low doses are also often emerging from epidemiological data that statistically infer dose-infection relationships; for example, C. parvum in the human water supply (Englehardt & Swartout 2004), gamma-herpesvirus (Tibbetts et al 2003), outbreaks of E. coli (Teunis et al 2004) or cases such as foot-and-mouth disease virus in cattle (Schijven et al 2005).…”