Protective antigen

Subunit vaccines based on the surface proteins of vims are also being explored. It has been demonstrated that the two major protective antigens are haemagglutinin (HA) and neuraminidase (NA). The genes for these antigens have been cloned and expressed in baculovims in insect cell culture (84). 

The anthrax toxin is a tripartite toxin and consists ofthe binding component protective antigen (PA), the lethal factor (LF), which is a metalloprotease, and the edema factor (EF), which is a calmodulin-dependent adenylyl-cyclase. Both enzyme components are translocated via PA into target cells. PA is activated by furin-induced cleavage and forms heptamers, which are similar to the binding components of C2 toxin and iota toxin. In the low pH compartment of endosomes, the heptamers form pores to allow translocation of LF and EF. LF cleaves six of the seven MEKs (MAPK-kinases) thereby inhibiting these enzymes. The functional consequence is the blockade of the MAPK pathways that control cell proliferation, differentiation, inflammation, stress response, and survival. Whether this is the reason for the LT-induced cell death of macrophages is not clear [1]. 

Anthrax Medium from cuitures of B. anthracis 1 Separation of protective antigen from medium 2 Adsorption 3 + 3 quantal assay in guinea-pigs using challenge with B. anthracis Exclusion of live 6. anthracis and of anthrax toxin... 

Homologues of H-gal-GP have been identified in O. ostertagi, T. circumcincta and Trichostrongylus vitrinus (Smith et al., 1993) and are being evaluated as protective antigens in the former two species. Preliminary results encourage cautious optimism, with moderate levels of protection being observed in some trials (W.D. Smith, 2000, unpublished results). 

Munn, E.A., Smith, T.S., Smith, EL, Smith, F. and Andrews, S.J. (1997) Vaccination against Haemonchus contortus with denatured forms of the protective antigen Hll. Parasite Immunology 19, 243—248. 

Smith, S.K., Pettit, D., Newlands, G.F.J., Redmond, D.L., Skuce, P.J., Knox, D.P. and Smith, W.D. (1999) Further immunisation and biochemical studies with a protective antigen complex from the microvillar membrane of the intestine of Haemonchus contortus. Parasite Immunology 21, 187—199. 

Smith, T.S., Munn, E.A., Graham, M., Tavemor, A.S. and Greenwood, C.A. (1993) Purification and evaluation of the integral membrane protein HI 1 as a protective antigen against Haemonchus contortus. InternationalJournalfor Parasitology 23, 271-280. 

Anthrax protective antigen Pag tml/tmA Prrn PpsbA/TpsbA 4-5% Daniell... 

The anthrax bioterrorist attacks that followed the events of September 11th 2001 resulted in a renewed interest BadUus anthracis, the causative agent of this disease. Research has focused on the development of better vaccines than the one currently available. It has been estimated that the aerosolized release of 100 kg of anthrax spores upwind of Washington DC would cause mortalities of 130,000-3,000,000 [63]. Nonetheless, wild-type Bacillus anthracis is susceptible to conventional antibiotics, including penicillin, oxyfloxacin and ciprofloxacin. The problem lies not with the bacterial infection itself, but with three proteins released by the bacteria - protective antigen (PA, 83 kDa), lethal factor (LF, 90 kDa) and edema factor (EF, 89 kDa) -known as anthrax toxins [63]. 

Bacillus anthracis protective antigen Tobacco leaf No immunogenicity assays. - 86... 

Expression of Potential Vaccine Antigens. In general, in the future, eukaryotic cell culture is likely to be the method of choice for the production of subunit vaccine antigens where the organism to be vaccinated against replicates in eukaryotic cells. E. coli are unable to posttranslationally modify some vaccine candidates for example, bacterial systems cannot add carbohydrate which is important in the antigenicity and structure of many protective antigens. 

Anthrax Anthrax is a toxin with three separate components a protective antigen (PA), an edema factor (EF), and a lethal factor (LF). 

Very recently the protein structures of ACE with the bound inhibitors Lisinopril (Fig. 4) and Captopril were published (101,102). Also the protein structure of the LF from Bacillus anthracis (PDB-Code 1J7N) caused a sensation, which is now available to the public (Fig. 14b) (103). LF is part of the toxic exotoxin complex composed of three distinct proteins (protective antigen PA, the lethal factor LF and the edema factor EF), and is thought to be the most toxic... 

Melnyk R.A., Hewitt K.M., Lacy D.B., Lin H.C., Gessner C.R., Li S., Woods V.L. Jr, Collier R.J. Structural determinants for the binding of anthrax lethal factor to oligomeric protective antigen. J. Biol. Chem. 

Anthrax toxin is a bacterial toxin from Bacillus anthracis consisting of three parts protective antigen (PA), lethal factor (LF) and edema factor (EF). Both LF and EF compete for binding sites on the PA protein. The PA protein binds with high affinity to an as yet unknown receptor on macrophages and related cell types. When PA is internalized by the target cells, it functions as a shuttle protein for either EF or LF. Intracellularly, in the acidic environment of the endosome, EF and LF are capable of entering the cytosol by pH-dependent pore formation [139]. 

Koya, V., Moayeri, M., Leppla, S.H., and Daniell, H. (2005). Plant-based vaccine mice immunized with chloroplast-derived anthrax protective antigen survive anthrax lethal toxin challenge. Infect. Immun. 73(12) 8266-8274. 

Azhar, A.M., Singh, S., Anand Kumar, R, and Bhutnagar, R. (2002). Expression of protective antigen in transgenic plants a step towards an edible vaccine against anthrax. Biochem. Biophys. Res. Commun. 299(3) 345-351. 

The discovery that oncosphere extracts provided a source of potent, protective antigens for both Taenia species and E. granulosus raised the potential for development of practical vaccines to prevent infections with economic and... 

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