Sônia França Correia Barbosa

Implications of Haemophilus influenzae Biogroup aegyptius Hemagglutinins in the Pathogenesis of Brazilian Purpuric Fever

Brazilian purpuric fever (BPF) is an acute disease caused by Haemophilus influenzae biogroup aegyptius; it is characterized by fever, purpura, and hypotensive shock and is usually fatal. The factors responsible for bacterial virulence and pathogenesis are poorly known. Hemagglutinins have been frequently associated with bacterial virulence, and, in the present study, hemagglutinating activity was detected in extracellular products from H. influenzae biogroup aegyptius strains isolated from patients with BPF. A 60-kilodalton (kDa) molecule absorbable by human O-type erythrocytes was identified by an immunoblot assay; a corresponding fraction was chromatographically purified, and its pathogenic effect was evaluated. Rabbits injected intravenously with either the whole bacterial extracellular product or the 60-kDa fraction showed reactions similar to those seen in patients with BPF: purpura, congestion, and fibrin thrombi in the inner organs. We suggest that this hemagglutinating factor is one of the major pathogenic components of BPF.

Fractionation of Crotalus durissus terrificus of chromatography technique by molecular exclusion

Atraves da tecnica de cromatografia de exclusao molecular utilizando Sephadex G-75 foram estudadas as diferentes fracoes do veneno de Crotalus durissus terrificus, uma das serpentes peconhentas mais comuns no Brasil. Foram obtidos 4 picos (correspondentes as fracoes 32, 60, 86 e 103) com peso molecular variando de 4.000 a 150.000. As fracoes de todo o diagrama de gel filtracao foram triadas atraves de reacao de imunoeletroforese a fim de se verificar suas cargas e velocidade de migracao. As linhas de precipitacao encontradas foram comparadas as 11 linhas apresentadas pela reacao de imunoeletroforese do veneno total contra o soro anti-crotalico. Constatou-se que as fracoes de um mesmo pico apresentavam caracteristicas proprias com excecao da fracao 54 (subida do pico II) que mostrou diferencas significativas em relacao a fracao 60. Apos a triagem foram escolhidas as fracoes de cada pico onde as linhas de precipitacao foram mais nitidas e intensas, para estudo de identidade atraves da reacao de difusao radial dupla e letalidade comparada a concentracao de 0,0625 mg/ml do veneno total que corresponde a DL50 em camundongo pelo metodo de SPEARM & KARBER. As fracoes 32, 86 e 103 correspondentes respectivamente aos picos I, III e IV apresentaram letalidade nula ou negligenciada e a fracao II foi a mais toxica.By means of chromatography technique by molecular exclusion using Sephadex G-75 were studied different fractions of venom Crotalus durissus terrificus, one the most common poisonous snakes in Brazil. It were obtained four peaks related to fractions 32, 60, 86 and 103, which molecular weight varied from 4.000 to 150.000. The fractions of all gel filtration diagram were screened through immunoelectrophoresis, in order to verify its charges and migration speed. The precipitation lines were compared with 11 lines obtained through immunoelectrophoresis of total venom against anti-Crotalus durissus terrificus serum. It was observed that fractions of same peak presented peculiar characteristics except fraction 54 (corresponding to the ascending of peak II), which showed significant differences when compared with fraction 60. After screening, fractions of each peak were chosen in order to identify means of double radial diffusion test and the letality was compared with 0,0625 mg/ml concentration of total venom, which corresponds to DL50 in mice by SPEARM & KARBER method. Fractions 32, 86 and 103 corresponding to peaks I, III and IV respectively, presented null or negligibe lethality, and fraction II was the most toxic.