ABSTRACT
A purified monovalent botulinum type F toxoid vaccine was administered to 35 healthy adult volunteers in a phase I clinical trial. Serum samples from the vaccinated volunteers were evaluated for an antibody response at various time intervals over 1 year by mouse bioassay and ELISA. The antibody response was measured for varying doses of vaccine (2, 5, or 10 microg), and after single or multiple (two or three doses @ 10 microg) vaccinations. Six out of 15 (40%) individuals developed antibody titers after receiving a single dose. After two and three vaccinations, there was a 90% (18/20) and 100% (10/10) seroconversion rate, respectively. Eight months after initial injection, 57 and 63% of individuals were antibody positive following two or three vaccinations, respectively. Single vaccinations, at any of the tested dosages, elicited lower, if any, antibody response than did multiple vaccinations. After the third vaccination, ELISA titers positively correlated with mouse neutralization bioassay titers (r(2)=0.86).
Subject(s)
Bacterial Vaccines/immunology , Botulinum Toxins/immunology , Adult , Animals , Antibodies, Bacterial/biosynthesis , Antibodies, Bacterial/blood , Bacterial Vaccines/administration & dosage , Dose-Response Relationship, Immunologic , Enzyme-Linked Immunosorbent Assay , Humans , Immunization Schedule , Mice , Predictive Value of TestsABSTRACT
Ricin is an RNA N-glycosidase that hydrolyzes a single adenine base from a conserved loop of 28S ribosomal RNA, thus inactivating protein synthesis. Molecular-dynamics simulation methods are used to analyze the structural interactions and thermodynamics that govern the binding of formycin 5'-monophosphate (FMP) and several of its analogs to the active site of ricin A-chain. Simulations are carried out initiated from the X-ray crystal structure of the ricin-FMP complex with the ligand modeled as a dianion, monoanion and zwitterion. Relative changes in binding free energies are estimated for FMP analogs constructed from amino substitutions at the 2- and 2'-positions, and from hydroxyl substitution at the 2'-position.
Subject(s)
Computer Simulation , Formycins/chemistry , Models, Molecular , Ribonucleotides/chemistry , Ricin/chemistry , Binding Sites , Crystallography, X-Ray , Formycins/metabolism , Molecular Structure , Protein Conformation , Ribonucleotides/metabolism , Ricin/metabolism , ThermodynamicsABSTRACT
Vibrio cholerae El Tor strains from Peru, Bangladesh, and Bahrain were attenuated by deletion of a genetic element that encodes virulence factors and RS1. The B subunit of ctx (ctxB) was reintroduced into the recA gene of the deletion mutants, rendering them unable to recombine with exogenous genetic elements and generating Peru-3, Bang-3, and Bah-3. Fifteen volunteers received one dose of various vaccine strains at 4 x 10(6) to 1 x 10(8) cfu. All strains colonized the gut. A > or = 4-fold rise in vibriocidal titer was observed in 14 volunteers, with titers of > or = 1600 in 13. Peru-3 was the least reactogenic, but 2 of 6 volunteers had loose stools. Peru-14, a filamentous motility-deficient mutant of Peru-3, was well tolerated and colonized 18 of 21 volunteers at doses of 2 x 10(6) to 1 x 10(9) cfu. Also, when 8 Peru-3 or Peru-5 vaccinees, 5 Peru-14 vaccinees, and 8 controls were challenged with 2 x 10(6) cfu V. cholerae El Tor Inaba (N16961), 11 vaccinees were protected compared with no controls. Peru-14 shows promise as a safe, effective, single-dose oral vaccine against El Tor cholera.
Subject(s)
Cholera Vaccines , Cholera/prevention & control , Adolescent , Adult , Animals , Animals, Suckling , Antibodies, Bacterial/blood , Cholera Vaccines/adverse effects , Cholera Vaccines/genetics , Cholera Vaccines/immunology , Feces/microbiology , Female , Genes, Bacterial/genetics , Humans , Immunoglobulin G/blood , Intestines/microbiology , Male , Mice , Recombination, Genetic , Sequence Deletion , Vaccination , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Vibrio cholerae/genetics , Vibrio cholerae/growth & development , Vibrio cholerae/immunology , Vibrio cholerae/pathogenicity , VirulenceABSTRACT
Seven monoclonal antibodies (mAbs) were developed against neurotoxin I (NT-1), a protein from central Asian cobra (Naja naja oxiana) venom which binds specifically to nicotinic acetylcholine receptor (AchR). All of the mAbs cross-reacted with another long-chain post-synaptic neurotoxin, Bungarus multicinctus alpha-bungarotoxin (alpha-BT), but not Naja naja kaouthia alpha-cobratoxin, in an enzyme-linked immunosorbent assay (e.l.i.s.a.). Short-chain post-synaptic neurotoxins like Naja naja atra cobrotoxin, Laticauda semifasciata erabutoxin b, or N. n. oxiana neurotoxin II did not cross-react with the NT-1 mAbs, but an antigen(s) found in Dendroaspis polylepis, Acanthophis antarcticus and Pseudechis australis venoms was immunoreactive. The e.l.i.s.a. readings for dithiothreitol-reduced NT-1 and NT-1 mAbs ranged from 13 to 27% of those for native toxin but reduced alpha-BT was not immunoreactive. Synthetic NT-1 peptides were used in epitope-mapping studies and two, non-contiguous regions (Cys15-Tyr23 and Lys25-Gly33 or Pro17-Lys25 and Asp29-Lys37) were recognized by the NT-1 mAbs. The NT-1 mAbs individually inhibited 31-71% of alpha-BT binding to AchR in vitro and afforded a slight protective effect in vivo with a toxin: antibody mole ratio of 1:1.5. This report is the first to describe mAbs which recognize and protect against a heterologous, long-chain, post-synaptic neurotoxin from snake venom.