The Secreted Triose Phosphate Isomerase of Brugia malayi Is Required to Sustain Microfilaria Production In Vivo

Abstract

Human lymphatic filariasis is a major tropical disease transmitted through mosquito vectors which take up microfilarial larvae from the blood of infected subjects. Microfilariae are produced by long-lived adult parasites, which also release a suite of excretory-secretory products that have recently been subject to in-depth proteomic analysis. Surprisingly, the most abundant secreted protein of adult Brugia malayi is triose phosphate isomerase (TPI), a glycolytic enzyme usually associated with the cytosol. We now show that while TPI is a prominent target of the antibody response to infection, there is little antibody-mediated inhibition of catalytic activity by polyclonal sera. We generated a panel of twenty-three anti-TPI monoclonal antibodies and found only two were able to block TPI enzymatic activity. Immunisation of jirds with B. malayi TPI, or mice with the homologous protein from the rodent filaria Litomosoides sigmodontis, failed to induce neutralising antibodies or protective immunity. In contrast, passive transfer of neutralising monoclonal antibody to mice prior to implantation with adult B. malayi resulted in 60–70% reductions in microfilarial levels in vivo and both oocyte and microfilarial production by individual adult females. The loss of fecundity was accompanied by reduced IFNγ expression by CD4+ T cells and a higher proportion of macrophages at the site of infection. Thus, enzymatically active TPI plays an important role in the transmission cycle of B. malayi filarial parasites and is identified as a potential target for immunological and pharmacological intervention against filarial infections.

Crystal structures of Triosephosphate Isomerases from Taenia solium and Schistosoma mansoni provide insights for vaccine rationale and drug design against helminth parasites

“…SmTPI and TsTPI were purified to homogeneity with a yield of approximately 5 mg/ml after two purification steps (S1 Fig). Steady-state kinetics of recombinant TsTPI and SmTPI show that those enzymes present similar kinetic profiles to those previously reported and with the activity ranges of TPIs from Fasciola hepatica and Brugia malayi [33,44,45,54,55] (Table 1).…”

“…The prediction that the SXD/E insert elicits a weak immune response and its conservation among parasitic helminth are counterintuitive. TPIs from parasitic helminths are secreted proteins [33,35,36,66] and the solvent exposed localization of the SXD/E insert suggests that this motif may be involved in the moonlighting proteins of parasitic TPIs [33] and thus a key component during helminth infection.…”

“…Upon infection, TPIs from helminths elicit an antibody response as this protein localizes on the surface of the parasite or is secreted [33][34][35][36]. TPI is a vaccine candidate against S. japonicum infection in mice, buffaloes, and pigs [10,11,34,37,38].…”

Metabolite profiling of infection-associated metabolic markers of onchocerciasis

“…Triose phosphate isomerase is one of the most abundant proteins in the excretorysecretory proteins of filarial parasites [32-34] and catalyzes the interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate (DHAP) that end up in pyruvate. Though both glyceraldehyde-3-phosphate and DHAP were not detected, the precursor glycerol-3- phosphate was significantly lower in the Ov-infected individuals.…”

Cloning and molecular identification of triosephosphate isomerase gene from Apis cerana cerana and its role in response to various stresses

“…The role of pesticides in honeybee colony losses, with their sub-lethal and synergistic effects, has recently regained consideration (Boncristiani et al 2012). TPI also plays an important role in response to adverse environmental conditions (Hewitson et al 2014). TPI is highly up-regulated under stress conditions in mammalian cells (Yamaji et al 2004).…”