Immunization with Brugia malayi Calreticulin Protein Generates Robust Antiparasitic Immunity and Offers Protection during Experimental Lymphatic Filariasis

Abstract

Lymphatic filariasis causes permanent and long-term disability worldwide. Lack of potent adulticidal drugs, the emergence of drug resistance, and the nonavailability of effective vaccines are the major drawbacks toward LF elimination. However, immunomodulatory proteins present in the parasite secretome are capable of providing good protection against LF and thus offer hope in designing new vaccines against LF. Here, we evaluated the immunogenicity and protective efficacy of B. malayi calreticulin protein (BmCRT) using in vitro and in vivo approaches. Stimulation with recombinant BmCRT (rBmCRT) significantly upregulated Th1 cytokine production in mouse splenocytes, mesenteric lymph nodes (mLNs), and splenic and peritoneal macrophages (PMΦs). Heightened NO release, ROS generation, increased lymphocyte proliferation, and increased antigen uptake were also observed after rBmCRT exposure. Mice immunized with rBmCRT responded with increased Th1 and Th2 cytokine secretion and exhibited highly elevated titers of anti-BmCRT specific IgG at day 14 and day 28 postimmunization while splenocytes and mLNs from immunized mice showed a robust recall response on restimulation with rBmCRT. Infective larvae (L3) challenge and protection studies undertaken in Mastomys coucha, a permissive model for LF, showed that rBmCRT-immunized animals mounted a robust humoral immune response as evident by elevated levels of total IgG, IgG1, IgG2a, IgG2b, and IgG3 in their serum even 150 days after L3 challenge, which led to significantly reduced microfilariae and worm burden in infected animals. BmCRT is highly immunogenic and generates robust antiparasitic immunity in immunized animals and should therefore be explored further as a putative vaccine candidate against LF.

Immunophenotypic and Functional Characterization of Eosinophil and Migratory Dendritic Cell Subsets during Filarial Manifestation of Tropical Pulmonary Eosinophilia

“…Flow-sorted Cont. rEos, TPE rEos, and TPE iEos ( n = 50,000) were incubated in separate tubes in the presence of FITC-dextran (1 mg/mL) for 2 h in a 5% CO 2 incubator set at 37 °C, and the increase in FITC fluorescence was measured using flow cytometry, as described previously. ,, …”

The many faces of parasite calreticulin

“…Other parasites whose Calr has displayed the capacity to inhibit the complement pathway include, Trypanosoma carassii ( 70 ), E. histolytica ( 16 ), E. dispar ( 71 ), Brugia malayi ( 72 , 73 ), Wuchereria bancrofti ( 19 ), Trichinella spiralis ( 20 , 74 ), O. viverrini ( 75 ), Haemonchus contortus ( 76 , 77 ), Necator americanus ( 76 , 78 ), S. mansoni and S. japonicum ( 79 ), among others. An apparent exception to this rule is found in the Calr of the tick Amblyomma americanum , which is present in the saliva of the specimen.…”

“…Yadav et al. ( 19 ) inoculated mice with recombinant Calr from B. malayi (rBmCalr), the causative agent of lymphatic filariasis (also known as elephantiasis). It was shown that rBmCalr activated peritoneal macrophages and splenocytes stimulated the production of cytokines characteristic of the Th1 response, such as IL-6, IL-2, IFN-γ and TNF-α.…”

“…In spite of the coincidence in amino acid sequence and function between parasite and host Calr, the former is highly immunogenic and, as such, has been used as an immunogen in order to generate immunity against various infectious parasites. Yadav et al (19) inoculated mice with recombinant Calr from B. malayi (rBmCalr), the causative agent of lymphatic filariasis (also known as elephantiasis). It was shown that rBmCalr activated peritoneal macrophages and splenocytes stimulated the production of cytokines characteristic of the Th1 response, such as IL-6, IL-2, IFN-g and TNF-a.…”

Spatial transcriptomics reveals antiparasitic targets associated with essential behaviors in the human parasiteBrugia malayi

“…The authors declare no competing interests. 16,33,[94][95][96][97][98][99][100][101] , compared to a more diffuse pattern of expression for proteins identified in secretome studies (teal) 31,32 . (D) Heatmap of gene expression patterns shows head-enrichment of candidate vaccine targets, as well as both head-and body-enrichment for the targets of antifilarial drugs (benzimidazoles: β-tubulins, macrocyclic lactones: GluCls, and emodepside: BK channel).…”