Characterization of<i>Entamoeba histolytica</i>Intermediate Subunit Lectin-Specific Human Monoclonal Antibodies Generated in Transgenic Mice Expressing Human Immunoglobulin Loci

Tachibana, Hiroshi; Cheng, Xunjia; Tsukamoto, Hideo; Itoh, Johbu

doi:10.1128/iai.01002-08

Cited by 18 publications

(15 citation statements)

References 55 publications

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“…No biological data are available for these immunoglobulin molecules, but it is likely that the VH3 antibody is the major immunoglobulin to SAG1 of T. gondii. This appears to agree well with the proposal that VH3 antibodies are important for defense against a variety of viruses (2,15) and bacteria (1,29), as well as a parasite (31,34). The closest V germ line in the light chains was V1-17, and the J segments were J4 in Tox203 and J1 in Tox1403.…”

Section: Discussionsupporting

confidence: 78%

Generation of a Neutralizing Human Monoclonal Antibody Fab Fragment to Surface Antigen 1 ofToxoplasma gondiiTachyzoites

Feng

Ohnishi

et al. 2011

Infect Immun

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A combinatorial immunoglobulin gene library was constructed from lymphocytes in peripheral blood of a patient with toxoplasmosis and screened for production of human monoclonal antibody Fab fragments to recombinant surface antigen 1 (SAG1) of Toxoplasma gondii. Two Fab clones, Tox203 and Tox1403, which consisted of a common heavy chain and different light chains, showed positive staining on the entire surface of tachyzoites in confocal microscopy. Sequence analysis of the heavy-chain gene revealed that the closest germ line V segments were VH3-23. The germ line D segment was D1-7, and the closest germ line J segment was JH4. In the light-chain genes, the closest germ line V segment was V1-17 with the J1 or J4 segments. The dissociation constants of these Fab fragments with recombinant SAG1 were 3.09 ؋ 10 ؊9 M for Tox203 and 2.01 ؋ 10 ؊8 M for Tox1403, indicating that the affinity of Tox203 was 7 times higher than that of Tox1403. Preincubation of T. gondii tachyzoites with Tox203 significantly inhibited their attachment to cultured MDBK cells. Passive immunization of mice with Tox203 also significantly reduced mortality after challenge with T. gondii tachyzoites. This is the first report of bacterial expression of human monoclonal antibody Fab fragments to SAG1 of T. gondii. These results also demonstrate that human Fab fragments to SAG1 might be applicable for immunoprophylaxis of toxoplasmosis.Toxoplasma gondii is an obligate intracellular parasite in the phylum Apicomplexa and infects a variety of warm-blooded domestic and wild animals worldwide. It is an important foodborne parasite transmitted primarily from animals to humans through meat, as well as through oocysts shed by cats into the environment (25). Infection in humans is usually asymptomatic in immunocompetent hosts. However, primary infection during pregnancy can result in severe neonatal malformations and ocular complications in the fetus. In immunocompromised hosts such as patients with human immunodeficiency virus/ AIDS, reactivation of the latent infection results in symptomatic diseases such as toxoplasmic encephalitis (14,22). Transmission of T. gondii by organ transplantation from a seropositive donor to a seronegative recipient is also an important potential cause of disease in heart, heart-lung, kidney, liver, and liver-pancreas transplant patients (25).The surface of T. gondii is the first component to contact the host cells. The T. gondii surface is coated by closely related antigens that belong to the surface antigen 1 (SAG1)-related sequences (SRS) superfamily (13, 16). SAG1 is the most abundant and immunogenic of these antigens and is important for the process of invasion. Treatment of T. gondii with mouse monoclonal or rabbit polyclonal antibodies to SAG1 inhibits parasite attachment to host cells (24). Fab fragments derived from a mouse monoclonal antibody also showed dose-dependent inhibition of parasite attachment (23). Therefore, human monoclonal antibodies to SAG1 may be applicable for prevention of transmission and reactivation ...

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Section: Discussionsupporting

confidence: 78%

Generation of a Neutralizing Human Monoclonal Antibody Fab Fragment to Surface Antigen 1 ofToxoplasma gondiiTachyzoites

Feng

Ohnishi

et al. 2011

Infect Immun

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“…Purified human mAb XEhI-20 (anti-EhIgl1) and XEhI-B5 (anti-EhIgl2) were used for detection of Igls of E . histolytica [ 7 ]. Mouse mAb ED2-495 against recombinant Igl2 of E .…”

Section: Methodsmentioning

confidence: 99%

“…Anti-mouse and anti-rabbit immunoglobulin F(ab’)2 fragments conjugated with HRP (Amersham) were diluted 3000 times with PBST and used as the secondary antibody. Immunoblot assays with XEhI-20 or XEhI-B5 [ 7 ] were performed using SDS-PAGE in a 5–20% gradient gel under non-reducing conditions, with 30 μg of XEhI-20 or XEhI-B5 used as the primary antibody and HRP-labeled goat anti-human IgG antibody (MP Biomedicals) diluted 1000 times with PBST as the secondary antibody. Immobilon ™ Western (Millipore) was used as a substrate for visualization of the proteins.…”

Section: Methodsmentioning

confidence: 99%

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Comparison of hemolytic activity of the intermediate subunit of Entamoeba histolytica and Entamoeba dispar lectins

et al. 2017

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Galactose and N-acetyl-D-galactosamine-inhibitable lectin of Entamoeba histolytica has roles in pathogenicity and induction of protective immunity in rodent models of amoebiasis. Recently, the intermediate subunit of the lectin, Igl1, of E. histolytica has been shown to have hemolytic activity. However, the corresponding lectin is also expressed in a non-virulent species, Entamoeba dispar, and another subunit, Igl2, is expressed in the protozoa. Therefore, in this study, we compared the activities of Igl1 and Igl2 subunits from E. histolytica and E. dispar using various regions of recombinant Igl proteins expressed in Escherichia coli. The recombinant E. dispar Igl proteins had comparable hemolytic activities with those of E. histolytica Igl proteins. Furthermore, Igl1 gene-silenced E. histolytica trophozoites showed less hemolytic activity compared with vector-transfected trophozoites, indicating that the expression level of Igl1 protein influences the activity. These results suggest that the lower hemolytic activity in E. dispar compared with E. histolytica reflects the lower expression level of Igl1 in the E. dispar parasite.

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“…Therefore, it appears that in addition to pathogenesis, these molecules may have a basic role in Entamoeba biology. The role of these molecules in attachment to target cells and resistance to complement has been amply demonstrated using monoclonal antibodies that were able to block attachment and subsequent invasion [59]. Moreover, dominant-negative phenotype of the Hgl subunit of the Gal/GalNAc lectin showed reduced cell adhesion activity and tissue invasion capacity, indicating a signaling pathway involving the cell-surface lectin molecules [60].…”

Section: Cell Surface Molecules Of E Histolyticamentioning

confidence: 98%

Molecular Basis of Pathogenesis in Amoebiasis

Saha

Gaurav

Bhattacharya

et al. 2015

Curr Clin Micro Rpt

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Amoebiasis is one of the major public health problems in developing countries. In spite of the availability of an effective drug and absence of overt drug resistance, the disease is still prevalent among large population and spread over a number of countries. It is caused by the protist parasite Entamoeba histolytica that essentially infects humans, though other species that infect a few animals have been reported. A number of molecular techniques have recently been developed. These have helped in understanding biological processes in E. histolytica and in the identification of key molecules that are involved in amoebic virulence and invasion. Moreover, developments in the area of disease and invasion models have allowed understanding of these processes at molecular level and circumvented lack of a good animal model of amoebiasis. All these knowledge will help us to design better therapeutics and allow us to control this important disease.

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Characterization ofEntamoeba histolyticaIntermediate Subunit Lectin-Specific Human Monoclonal Antibodies Generated in Transgenic Mice Expressing Human Immunoglobulin Loci

Abstract: Four fully human monoclonal antibodies (MAbs) to

Cited by 18 publications

References 55 publications

Generation of a Neutralizing Human Monoclonal Antibody Fab Fragment to Surface Antigen 1 ofToxoplasma gondiiTachyzoites

Generation of a Neutralizing Human Monoclonal Antibody Fab Fragment to Surface Antigen 1 ofToxoplasma gondiiTachyzoites

Comparison of hemolytic activity of the intermediate subunit of Entamoeba histolytica and Entamoeba dispar lectins

Molecular Basis of Pathogenesis in Amoebiasis

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