Renata Chagas Bastos

Evaluation of an ELISA for canine leishmaniasis immunodiagnostic using recombinant proteins

The present work describes the isolation and purification of two Leishmania chagasi (= syn. Leishmania infantum) recombinant proteins, rLci2B and rLci1A, and their use in the development of an immunoassay for the diagnostic of canine leishmaniasis. After protein expression and cell disruption, rLci2B was purified by immobilized metal affinity chromatography followed by size exclusion chromatography, whereas rLci1A, expressed as an inclusion body, was treated with urea and purified by anion‐exchange chromatography. Homogeneities were ascertained by denaturing gel electrophoresis (MW rLci2B = 46 370; MWrLci1A = 88 400), isoelectric focusing (pI rLci2B = 5·91; pI rLci1A = 6·01) and Western blot. An indirect ELISA was developed using the purified antigens rLci2B and rLci1A and a leishmaniasis canine serum panel (n = 256). The ELISA showed 100% sensitivity and 95% specificity for rLci2B and 96% sensitivity and 92% specificity for rLci1A. The purified proteins did not present cross‐reactivity with sera from dogs infected with Trypanosoma caninum, Babesia canis and Ehrlichia canis. Cross‐reaction was verified with sera from dogs infected with Leishmania brasiliensis (11·7% for rLci2B and 2·9% for rLci1A). Based on ELISA results, it is suggested the use of rLci2B and rLci1A as antigens in an alternative serological assay for diagnostic of canine leishmania.

Determination of hydrazine in a meningococcal C conjugate vaccine intermediary product.

In Brazil, polysaccharide-protein conjugate vaccine against Neisseria meningitidis group C (MenCPS-TT) using hydrazine-activated-tetanus toxoid (TT) as a carrier protein has been developed. Because of the toxicity of hydrazine in humans, it is necessary to monitor this substances process control step during the vaccine production. The electroanalytical methodology was developed and validated for the determination of hydrazine during the process control of MenCPS-TT vaccine production by differential pulse polarography. The reduction potential was -0.95 V in acetone and sulphuric acid solution. The method presented linear range between 30 and 150 microgL(-1)and recovery of 93.5+/-0.8%.

Brazilian meningococcal C conjugate vaccine: scaling up studies

Several outbreaks caused by Neisseria meningitidis group C have been occurred in different regions of Brazil. A conjugate vaccine for Neisseria meningitidis was produced by chemical linkage between periodate-oxidized meningococcal C polysaccharide and hydrazide-activated monomeric tetanus toxoid via a modified reductive amination conjugation method. Vaccine safety and immunogenicity tested in Phase I and II trials showed satisfactory results. Before starting Phase III trials, vaccine production was scaled up to obtain industrial lots under Good Manufacture Practices (GMP). Comparative analysis between data obtained from industrial and pilot scales of the meningococcal C conjugate bulk showed similar execution times in the scaling up production process without significant losses or alterations in the quality attributes of purified compounds. In conclusion, scale up was considered satisfactory and the Brazilian meningococcal conjugate vaccine production aiming to perform Phase III trials is feasible.