Approach to the diagnosis and management of snakebite envenomation in South Africa in humans.

Snakebites occur in the community, not in the Emergency Unit. As such it is important to understand the first-aid concepts and pre-hospital emergency care aspects of this neglected disease. This article will highlight the concepts for emergency care within the context of the current pre-hospital arena and in light of the recent South African Snakebite Symposium consensus meeting held in July 2022, where wilderness rescue, emergency medical services and other medical participants agreed through evidence review and consensus debate on the current best approaches to care of the snakebite victim outside the hospital environment.

The natBr(p,x) (73,75)Se nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling.

A possible route for the production of no-carrier-added (n.c.a.) 73Se (T(1/2) = 7.1 h) and 75Se (120 d) is introduced. D,L-2-Amino-4-([73Se]methyl-seleno) butanoic acid (D,L-[73Se]selenomethionine) with an overall radiochemical yield of > 40% could be prepared via a 3-step polymer-supported synthesis after successful separation of 73Se from KBr targets. Excitation functions for the natBr(p,x) (72,73,75)Se processes were measured from threshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradiated at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated 73Se yield (EOB) for 1 h irradiation in 1 microA of beam at the optimum proton energy range of 62-->42 MeV is 81.4 MBq (2.2 mCi), and the calculated 75Se yield (EOB) for the overall range 62 MeV-->threshold for the same irradiation conditions is 0.97 MBq (0.026 mCi).

Isolation of a capsid protein of bluetongue virus that induces a protective immune response in sheep.

A method to purify the neutralization specific antigen of bluetongue virus P2 in large amounts has been developed. The purified protein is free from virus-specified or cellular contaminants and its immunological specificity has been preserved. The purification is based on the observation that protein P2 can be dissociated from the virion by treatment with monovalent or divalent salts. The salt concentration required to solubilize the outer capsid proteins is pH dependent and in general decreases with a decrease in pH. P2 purified by extraction from polyacrylamide gels does not induce immune-precipitating or neutralizing antibodies. The response against P5, on the other hand, is much less conformational dependent and P5 purified from gels readily induces P5-precipitating antibodies in rabbits. These antibodies do not neutralize the virus. Purified P2, immunoabsorbed with anticore serum to remove trace amounts of P7, was injected into sheep. An initial dose of 50 micrograms of P2 was sufficient to induce P2-precipitating antibodies as well as neutralizing and hemagglutination-inhibiting antibodies. These sheep were fully protected against challenge with a virulent strain of the same BTV serotype. Lower doses of P2 still provided a significant level of protection even though no neutralizing antibodies could be detected.

Immune response against the purified serotype specific antigen of bluetongue virus and initial attempts to clone the gene that codes for the synthesis of this protein.

Sheep were injected with different amounts of purified protein P2 of bluetongue (BT) virus (BTV). About 3 X 50 mcg was required for the induction of neutralizing antibodies. Sheep injected with 3 X 10 mcg were, however, still largely protected when challenged with virulent virus. This has suggested the possibility of using P2 as a subunit vaccine and initiated an investigation of the possibility of synthesizing P2 by DNA-recombinant technology. In order to clone the gene that codes for the synthesis of P2 both the "shotgun" approach with unfractionated dsRNA and cloning of isolated segment 2 were investigated. The basic approach was to convert the dsRNA to DNA which was cloned into the Pst 1 site of E. coli plasmid pBR322. The largest BTV-specific insert that was obtained in the initial experiments was just more than 2,000 base pairs long. The largest insert obtained when isolated segment 2 dsRNA was cloned was about 1,200 base pairs which represents about 1/3 of the P2 gene.

A haemagglutination and haemagglutination inhibition test for bluetongue virus.

Haemagglutination of bluetongue virus (BTV) was demonstrated for the first time by making use of a purified preparation of the virus. The reaction was found to be independent of variations in the pH, temperature, buffer system and origin of the erythrocytes used in the test. A haemagglutination inhibition test, subsequently developed, was demonstrated to be serotype specific. The storage of the virus for indefinite periods was facilitated by lyophilization of BTV in the presence of a low concentration of sucrose.

Factors affecting the bluetongue virus neutralizing antibody response and the reaction between virus and antibody.

A study was made of different aspects of the bluetongue virus neutralizing antibody response and the reaction between the virus and antibody. Optimum neutralization was obtained in a 2mM Tris-HCl buffer, pH 9,0, at a temperature of 4 degrees C. The reaction of virus and antibody could be demonstrated by electron microscopy in the formation of clumps which were shown to be serotype specific. It was found that both IgM and IgG antibodies can neutralize the virus, but that IgM reached its maximum level sooner after infection than IgG.