Comparison of immune responses in mice infected with different strains of Strongyloides venezuelensis

Abstract

In human hosts and in murine models, the immune response to Strongyloides spp. is Th2 type. In addition, the profile of the host immune response follows various symptoms induced by Strongyloides spp. In the present study, we demonstrated that the L2 and L49 strains of Strongyloides venezuelensis obtained from Bolomys lasiurus and Nectomys squamipes induced significant and similar increases in eosinophil/mononuclear cell counts in the blood, peritoneal cavity fluid and bronchoalveolar lavage fluid when compared with uninfected mice. However, in the first 3 days of infection, IL-4, IL-5 and IFN-gamma levels were higher in the lungs of mice infected with the L2 strain, which also presented greater production of IgG and IgG1 than did mice infected with the L49 strain. The higher antibody and cytokine levels induced by the L2 strain correlated with a decrease in the number of female parasites recovered in the faeces of mice on post-infection day 7. The results demonstrate that the L2 strain was a more potent stimulant of the humoral immune response, which can result in more efficient antibody-dependent cell-mediated cytotoxicity, a mechanism involved in eosinophil activation and parasite elimination. Further studies are needed in order to elucidate the molecular differences among parasites.

Recovery from Strongyloides venezuelensis infection in Lewis rats is associated with a strong Th2 response

“…This tendency became evident at the recovery phase when IgG1 but not IgG2b presented a significant increase compared with that in the acute infection. These results are similar to the ones described in mice infected with S. venezuelensis (3) and Wistar rats infected with S. ratti (5). Wilkes et al.…”

“…However, different kinds of immune response can be observed with different strains of Strongyloides spp. Recently, a study comparing two heterologous strains of S. venezuelensis showed that the strains differed in the stimulation of humoral immune response (3). The dynamics of S. venezuelensis infection, especially concerning the kinetics of egg elimination, the induced immunity and the tissue migration route, are already known in Wistar rats (8,9) and in several mice strains (10), but not in Lewis rats.…”

Update on Strongyloidiasis in the Immunocompromised Host

“…Mice have been provided with immunity by transferring human IgG [22]. Moreover, L2 strains could have more potent stimulus of humoral response than L3 in mice [23]. Interestingly, in some nematodes, the Th1 response is elucidated with low intensity of infection, whereas Th2 is induced with high doses of worms [24].…”

Increased susceptibility to Strongyloides venezuelensis infection is related to the parasite load and absence of major histocompatibility complex (MHC) class II molecules

“…In immunocompromised patients with excess parasites the disease may become potentially fatal due to hyperinfection syndrome and dissemination, besides being related to the highest mortality rate (Grove, 1996). However, there has been little investigation into the causes of this disease presentation form and the worst outcome (Machado et al, 2007).…”