The malaria sporozoite injected into a host by the bite of the mosquito vector initiates the parasite cycle that culminates in clinical disease. This sporozoite stage is highly antigenic, and immunization with irradiated sporozoites has prevented the development of malaria in rodent and simian hosts as well as in several human volunteers (1). Antisporozoite antibodies detectable in the sera of the immunized primate hosts appear to be associated with immune resistance.Recently, hybridoma-derived monoclonal antibodies directed against sporozoites of rodent and simian malaria were found to be protective, i.e., to abolish sporozoite infectivity both in vivo (2) and in vitro (3). 1 These antibodies react with circumsporozoite (CS) 2 proteins; that is, stage-and species-specific polypeptides that are uniformly distributed over the entire surface of the parasite and that are shed when cross-linked by antibodies (2, 4). 1The hybridoma technique was therefore used to develop monoclonal antibodies against sporozoites of P falciparum and P. vivax in an attempt to identify the protective antigens of the human pathogens for their application in a vaccine.
Materials and MethodsMice. BALB/c mice were immunized using viable and frozen sporozoites of P.falciparum or P. vivax. The P. falciparum spomzoites were of West African origin and were obtained by membrane feeding Anopheles gambiae mosquitoes on blood obtained from patients carrying P. falciparum gametoeytes. P. vivax sporozoites for immunization were obtained from Anopheles
The current treatment of botulism is to administer animalderived antitoxin, which frequently causes severe adverse reactions in the recipients. In this study, a heavy chain antibody fragment (VH/V H H) phage display library was constructed by amplification of the immunoglobulin genes of a nonimmune camel, Camelus dromedarius, using primers specific to human VH gene segments. amino acid residues of BoTxA/LC, which are located near the S1 subsite of the catalytic cleft of the enzyme. Molecular docking revealed that CDR3 of the V H H17 bound to epitope in the toxin enzymatic cleft. Therefore, the BoTxA/LC neutralization by the V H H17 should be due to the V H H insertion into the enzymatic cleft of the toxin, which is usually inaccessible to a conventional antibody molecule. This antibody fragment warrants further development as a therapeutic agent for botulism.
Periplaneta americana is the predominant cockroach (CR) species and a major source of indoor allergens in Thailand. Nevertheless, data on the nature and molecular characteristics of its allergenic components are rare. We conducted this study to identify and characterize the P. americana allergenic protein. A random heptapeptide phage display library and monoclonal antibody (MAb) specific to a the P. americana component previously shown to be an allergenic molecule were used to identify the MAb-bound mimotope and its phylogenic distribution. Two-dimensional gel electrophoresis, liquid chromatography, mass spectrometry, peptide mass fingerprinting, and BLAST search were used to identify the P. americana protein containing the MAb-specific epitope. We studied the allergenicity of the native protein using sera of CR-allergic Thai patients in immunoassays. The mimotope peptide that bound to the MAb specific to P. americana was LTPCRNK. The peptide has an 83–100% identity with proteins of Anopheles gambiae, notch homolog scalloped wings of Lucilia cuprina, delta protein of Apis mellifera; neu5Ac synthase and tyrosine phosphatase of Drosophila melanogaster, and a putative protein of Drosophila pseudoobscura. This finding implies that the mimotope-containing molecule of P. americana is a pan-insect protein. The MAb-bound protein of P. americana was shown to be arginine kinase that reacted to IgE in the sera of all of the CR-allergic Thai patients by immunoblotting, implying its high allergenicity. In conclusion, our results revealed that P. americana arginine kinase is a pan-insect protein and a major CR allergen for CR-allergic Thai patients.
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