Development of a Recombinant Antigen Vaccine against Infection with the Filarial Worm<i>Onchocerca volvulus</i>

Abraham, David; Leon, Ofra; Leon, Shalom; Lustigman, Sara

doi:10.1128/iai.69.1.262-270.2001

Cited by 61 publications

(56 citation statements)

References 51 publications

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“…Now that this phenomenon has been identified, selection of suitable patients for further in vitro studies of our recombinant larval O. volvulus antigen vaccine candidates will be greatly facilitated. At present, all of the cloned O. volvulus antigens found to be protective in the diffusion chamber model for mice are similarly recognized by sera from PI and INF individuals (1). Although effector mechanisms against infective L3 in the PI and concomitantly immune states may be very similar, the target antigens may be different.…”

Section: Discussionmentioning

confidence: 95%

Differential Cytokine and Antibody Responses to Adult and Larval Stages ofOnchocerca volvulusConsistent with the Development of Concomitant Immunity

et al. 2002

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The possibility of concomitant immunity and its potential mechanisms in Onchocerca volvulus infection were examined by analyzing cytokine and antibody responses to infective larval (third-stage larvae [L3] and molting L3 [mL3]), adult female worm (F-OvAg), and skin microfilaria (Smf) antigens in infected individuals in a region of hyperendemicity in Cameroon as a function of age. Peripheral blood mononuclear cell interleukin 5 (IL-5) responses to F-OvAg and Smf declined significantly with age (equivalent to years of exposure to O. volvulus). In contrast, IL-5 secretion in response to L3 and mL3 remained elevated with increasing age. Gamma interferon responses to L3, mL3, and F-OvAg were low or suppressed and unrelated to age, except for responses to Smf in older subjects. IL-10 levels were uniformly elevated, regardless of age, in response to L3, mL3, and F-OvAg but not to Smf, for which levels declined with age. A total of 49 to 60% of subjects had granulocytemacrophage colony-stimulating factor responses to all O. volvulus antigens unrelated to age. Analysis of levels of stage-specific immunoglobulin G3 (IgG3) and IgE revealed a striking, age-dependent dissociation between antibody responses to larval antigens (L3 and a recombinant L3-specific protein, O. volvulus ALT-1) which were significantly increased or maintained with age and antibody responses to F-OvAg, which decreased. Levels of IgG1 to L3 and F-OvAg were elevated regardless of age, and levels of IgG4 increased significantly with age, although not to O. volvulus ALT-1, which may have unique L3-specific epitopes. Immunofluorescence staining of whole larvae showed that total anti-L3 immunoglobulin levels also increased with the age of the serum donor. The separate and distinct cytokine and antibody responses to adult and infective larval stages of O. volvulus which are age related are consistent with the acquisition of concomitant immunity in infected individuals.The filarial parasite Onchocerca volvulus infects about 18 million people, and a further 100 million live in areas in which O. volvulus is endemic in Africa and Latin America. The resulting disease, onchocerciasis, is characterized by severe dermatitis and blindness (21). There is epidemiological evidence that acquired immunity against O. volvulus infection occurs in humans. For example, in regions of high endemicity, despite constant exposure to infected Simulium flies, 1 to 5% of the population exhibits no clinical manifestations of disease. These individuals are considered to be immune to infection and are referred to as putatively immune (PI) (15,17,46,47). Furthermore, in chronically infected (INF) individuals, the number of skin microfilariae (mf) tends to level off between the ages of 20 and 40 years, suggesting that these individuals have developed a means of limiting acquired infections (11). It has been suggested that the means of limiting acquired infections is through concomitant immunity (36), whereby newly introduced infective-stage larvae (third-stage larvae [L3]) are eliminated ...

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Section: Discussionmentioning

confidence: 95%

Differential Cytokine and Antibody Responses to Adult and Larval Stages ofOnchocerca volvulusConsistent with the Development of Concomitant Immunity

et al. 2002

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“…The number of L3 and the number of live L3 recovered from each mouse was used to calculate the % viable larvae recovered. Percent reduction was calculated as described by Abraham et al (2): % reductionϭ{(average worm survival in control miceϪaverage worm survival in immunized mice)/average worm survival in control mice}ϫ100.…”

Section: Methodsmentioning

confidence: 99%

The Larval Specific Lymphatic Filarial ALT‐2: Induction of Protection Using Protein or DNA Vaccination

Ramachandran

Kumar

Rami

et al. 2004

Microbiology and Immunology

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Genes from the infective stage of lymphatic filarial parasites expressed at the time of host invasion have been identified as potential vaccine candidates. By screening an L3 cDNA library with sera from uninfected longstanding residents of an area endemic for onchocerciasis, so‐called “endemic normals” (EN), we have cloned and characterized one such gene termed the abundant larval transcript two (ALT‐2). The stage specificity of ALT‐2 gene transcription and protein synthesis was confirmed by PCR using gene‐specific primers, and by western blot analysis of protein extracts from various stages of the parasite life cycle using specific antisera. Significant differences in antibody response to the recombinant ALT‐2 were observed in endemic populations with differing clinical manifestations of lymphatic filariasis with an antibody response present in sera from 18 of 25 (72%) EN subjects compared to 9 of 25 (36%) with subclinical microfilaracmia (MF) and 14 of 25 (52%) of those with chronic lymphatic obstruction (CP) (P=0.01 for comparison of EN to CP or to MF). This differential responsiveness suggests that the protective immunity postulated to account for their uninfected status might be associated with a response to this protein. When the utility of ALT‐2 as a vaccine candidate was tested in a murine model using either recombinant protein or a DNA vaccine construct, statistically significant protection was observed when compared to a control filarial gene product expressed across all stages of the parasite lifecycle (SXP‐1; P=0.02 for protein and P=0.01 for the DNA vaccine) or compared to adjuvant alone. This level of protection indicates that this vaccine is a promising candidate for further development.

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“…Polyclonal Sera Production and Immunolocalization of the Ov-SPI Proteins-Polyclonal sera raised against rOv-SPI-1 was produced in mice using the immunization protocol previously described (43). Briefly, 6-to 8-week-old male BALB/cByJ mice were injected subcutaneously with 25 g of rOv-SPI-1 in 0.1 ml of phosphate-buffered saline with 0.1 ml of (Sigma).…”

Section: Expression and Purification Of The Recombinant Ov-spi-1 (Rovmentioning

confidence: 99%

Characterization of a Novel Filarial Serine Protease Inhibitor, Ov-SPI-1, from Onchocerca volvulus, with Potential Multifunctional Roles during Development of the Parasite

Ford

Guiliano

Oksov

et al. 2005

Journal of Biological Chemistry

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A novel filarial serine protease inhibitor (SPI) from the human parasitic nematode Onchocerca volvulus, Ov-SPI-1, was identified through the analysis of a molting third-stage larvae expressed sequence tag dataset. Subsequent analysis of the expressed sequence tag datasets of O. volvulus and other filariae identified four other members of this family. These proteins are related to the low molecular weight SPIs originally isolated from Ascaris suum where they are believed to protect the parasite from host intestinal proteases. The two Ov-spi transcripts are up-regulated in the molting larvae and adult stages of the development of the parasite. Recombinant Ov-SPI-1 is an active inhibitor of serine proteases, specifically elastase, chymotrypsin, and cathepsin G. Immunolocalization of the Ov-SPI proteins demonstrates that the endogenous proteins are localized to the basal layer of the cuticle of third-stage, molting third-stage, and fourth-stage larvae, the body channels and multivesicular bodies of third-stage larvae and the processed material found between the two cuticles during molting. In O. volvulus adult worms the Ov-SPI proteins are localized to the sperm and to eggshells surrounding the developing embryos. RNA interference targeting the Ov-spi genes resulted in the specific knockdown of the transcript levels of both Ov-spi-1 and Ov-spi-2, a loss of native proteins, and a significant reduction in both molting and viability of third-stage larvae. We suggest the Ov-SPI proteins play a vital role in nematode molting by controlling the activity of an endogenous serine protease(s). The localization data in adults also indicate that these inhibitors may be involved in other processes such as embryogenesis and spermatogenesis.The cuticle is an extracellular hydroskeleton that overlays the hypodermis of all nematodes. Most nematodes molt their cuticles four times during pre-adult development. Although being fairly inert and structurally robust, the cuticle is also permeable to small compounds and expands during growth periods between molts (1). A number of enzymes have been implicated in the shedding of old cuticles and the remodeling process that occurs as the new cuticle develops (2-8). Proteolytic enzymes have been shown to play a vital role in these processes, and inhibitor studies and rational cloning strategies have identified several nematode proteases whose functions are required for molting (9 -11).To identify novel filarial proteins involved in the molting process, we adopted a transcriptomics approach. Thousands of expressed sequence tags (ESTs) 4 have been sequenced from cDNA libraries constructed from the infective third-stage larvae (L3) and molting L3 (mL3) of the human filarial nematode Onchocerca volvulus (12, 13). Analysis of these datasets identified novel cysteine proteases involved in the molting process (14,15). Also identified in these analyses was an O. volvulus small molecular weight serine protease inhibitor (SPI) with similarities to other nematode SPI; Ascaris suum chymotrypsin/elastase in...

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Development of a Recombinant Antigen Vaccine against Infection with the Filarial WormOnchocerca volvulus

Cited by 61 publications

References 51 publications

Differential Cytokine and Antibody Responses to Adult and Larval Stages ofOnchocerca volvulusConsistent with the Development of Concomitant Immunity

Differential Cytokine and Antibody Responses to Adult and Larval Stages ofOnchocerca volvulusConsistent with the Development of Concomitant Immunity

The Larval Specific Lymphatic Filarial ALT‐2: Induction of Protection Using Protein or DNA Vaccination

Characterization of a Novel Filarial Serine Protease Inhibitor, Ov-SPI-1, from Onchocerca volvulus, with Potential Multifunctional Roles during Development of the Parasite

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