Lucila Costallat Ricci

Human Immunodeficiency Virus Seroprevalence among Inmates of the Penitentiary Complex of the Region of Campinas, State of São Paulo, Brazil

Six hundred and ninety three male inmates from three penitentiaries, two (A and B) maximum-security systems and one (C) minimum-security facility, located in Campinas, State of São Paulo, Brazil were studied for the presence of human immunodeficiency virus (HIV) antibodies, using a cross-sectional design. The search for anti-HIV antibodies in 693 samples of sera collected was carried out by two serological tests: (a) the Microparticle enzyme immunoassay-HIV-1 and HIV-2 (MEIA) (Abbott Laboratories) and (b) the Western Blot-HIV-1 (WB) (Cambridge Biotech Corporation) to confirm positive results with MEIA. Sera reactivity for HIV antibodies was 14.4%. The highest frequency of anti-HIV antibodies was found in the A and B maximum-security prisons: 17% and 21.5%, respectively. In prison C, the frequency of reagents was 10.9%. Seventy three inmates, initially negative in the MEIA test, were checked again five and seven months later. Three of them, all from the maximum-security facilities, became reactive in the MEIA test, with confirmation in the WB, suggesting that serological conversion had occurred after imprisonment.

Modulating action of Escherichia coli heat-stable enterotoxin (STa) on the humoral immune response

The effect of Escherichia coli enterotoxin STa on the primary and secondary immune response in F1 (CBA × C57 B1/10) mice immunized against sheep red blood cells (SRBC) was investigated. Modulating action on the IgM and IgG response was found to be dependent on the dose-time administration of the toxin. Immunosuppression of the primary response on the 4th day after immunization was observed when the toxin was injected 15 min before the SRBC, followed by immunostimulation on the 6th day after antigen (Ag) injection. Moreover, toxin administration 48 h before SRBC caused immunosuppression of the primary immune response on the 4th and 6th days. On the other hand, the IgM and IgG secondary immune response, determined 6 days after boosting, was greatly enhanced by toxin administration 15 min before priming (day 0) or boosting (day 26) and 48 h before priming. The same response was suppressed by toxin administration 48 h before booster antigen injection.

Evaluation of a defined medium for the production of both thermolabile (LT) and thermostable (ST) enterotoxins ofEscherichia coli

The production of thermolabile (LT) enterotoxin was compared in a defined medium reported by Staples et al. (SAG medium) for the production of thermostable (ST) enterotoxin and the Casamino acids-Yeast extract (CAYE) medium. Aliquots were drawn from cultures of an enterotoxigenic (LT+, ST+)E. coli in both media at different times, growth curves were plotted, and culture filtrates tested for toxin activity. Levels of LT and ST in the SAG showed that it is as suitable as CAYE for the production of LT.The addition of either glucose (1%) or lincomycin (90 ug/ml) to SAG medium increased LT levels, but no synergistic effect could be observed if both substances were added concomitantly. Cultures in SAG medium incubated stationarily for 72 h at 37‡C yielded more LT than shaking cultures incubated similarly.

RESEARCH OF ANTIGEN AND ANTIBODIES FROM RETROVIRUSES, CMV AND HBV AMONG PRISONERS OF THE PENITENTIARY COMPLEX OF THE REGION OF CAMPINAS, SP, BRAZIL

Some viruses of the families Retroviridae, such as Human T Lymphotropic Virus (HTLV); Herpesviridae as the Cytomegalovirus (CMV) and Hepadnaviridae such as the Hepatitis B Virus (HBV) are liable to be co-transmitted with the Human Immunodeficiency Virus (HIV). Since prisoners are exposed to several and important risk factors involved in the transmission of HIV and the above mentioned viruses, male inmates from the penitentiary complex of Campinas, SP, Brazil, including HIV+ and HIV- ones, were examined for the presence of HTLV-I and/or II antibodies; IgG and IgM anti-CMV antibodies, and the research of the superficial hepatitis B antigen (HBsAg). The presence of anti-HTLV-I and/or II was determined by the Western Blot (WB) technique, whereas IgG and IgM anti-CMV and the search of HBsAg were carried out by the Microparticle Enzyme Immunoassay (MEIA-Abbott Lab). With regard to anti-HTLV-I and/or II, 58.3% (14/24-Number of positive reactions/number of sera examined) were reactive among the anti-HIV positive sera. Conversely, only 12.5% (3/24) among the HIV- negative sera showed positive reactions to HTLV-I and/or II antibodies. When looking for IgG anti-CMV percentages of 97.7% (43/44) and 95% (38/40) were obtained for anti-HIV positive and negative sera, respectively. As to IgM anti-CMV antibodies 11.36% (5/44) and 2.5% (1/40) of reactive sera were found for anti-HIV positive and negative, respectively. The HBsAg was found in 12.8% (5/39) of the sera which were anti-HIV positive.

Storage ofEscherichia coli thermolabile enterotoxin on filter papers for assay by immune haemolysis reactions

Thermolabile (LT) enterotoxin was prepared from stationary and shaken cultures of enterotoxigenicEscherichia coli (ETEC) grown in casamino acids-yeast extract medium and dried onto filter discs. These were then examined by a modification of the single radial immune haemolysis (SRIH) test. It was observed that LT antigenicity, as detected by this test, remained unaltered for as long as 30 days at room temperature.

Incidência de escherichia coli enterotoxigênica (ETEC), rotavirus e Clostridium perfringens de casos de diarréia em crianças, na região de Campinas, SP, Brasil

Foi realizada uma pesquisa na regiao de Campinas, SP, Brasil, sobre a presenca de Escherichia coli enterotoxigenica (ETEC), rotavirus e Clostridium perfringens enterotoxigenico em fezes diarreicas de criancas com ate 2 anos de idade. Dos 132 especimens fecais examinados quanto a presenca de ETEC 27 (20,45%) foram positivos. Destes foram isoladas 41 amostras de ETEC, das quais 40 produziram apenas a enterotoxina termolabil (LT) detectada pelo teste de imuno hemolise radial modifi cado. Entre as 183 amostras de fezes examinadas para rotavirus, 29 (15,84%) foram positivas pelas tecnicas de eletroforese em gel de poliacrilamida (PAGE) e ensaio imunoenzimatico (EIE), sendo que destas, 15 (51,7% ) foram provenientes de materiais coletados nos meses de inverno. Todas as amostras pertenciam ao grupo A e, atraves da tecnica de PAGE, pode-se observar que o tipo eletroforetico mais frequente (9 amostras) foi designado Ib, IIc, Illb, IVa, de acordo com a classificacao por nos adotada. Apenas 113 amostras de fezes foram examinadas para a presenca de C. perfringens enterotoxigenico. Para a deteccao da enterotoxina nos sobrenadantes das culturas foram utilizadas as tecnicas de hemaglutinacao passiva reversa e inoculacao intravenosa em camundongos, sendo encontradas 12 (10,61%) amostras entero-toxigenicas. Diante destes resultados e chamada a atencao sobre o valor apenas relativo de uma coprocultura convencional para fins de diagnostico, ressaltando-se a importância da criacao de metodos simplificados que favorecam a deteccao e identificacao dos grupos de agentes enteropatogenicos estudados na presente pesquisa.

Erythrocyte receptors for cholera and heat-labile enterotoxins of Escherichia coli

Many serological reactions using red blood cells (RBC) such as radial immune haemolysis (RIH) and indirect haemagglutination (IH) tests have often been used for the detection of cholera toxin (CT) and heat-labile (LT) enterotoxin produced by porcine and human Escherichia coli strains. In these tests, the enterotoxins bind to sheep, bovine and guinea-pig RBC without any ligand. We studied several factors which might interfere with such binding, as well as the nature of the receptors involved. Treatment of erythrocytes with different enzymes revealed that proteolytic enzymes had no effect on the adsorption of enterotoxins to RBC. Conversely, treatment with neuraminidase increased the adsorption. Experiments carried out with delipidized RBC revealed that none of the enterotoxins under study bound to the cells thus treated. Pre-incubation of ganglioside fractions with the enterotoxins blocked RIH and IH reactions and the biological effect of them on Vero cells. Assaying RBC ganglioside fractions by thin-layer chromatography revealed the presence of GM1. Our results suggest that the receptors for GT and LT enterotoxins in sheep, bovine and guinea pig RBC are gangliosides: mainly GM1.

Use of an indirect haemagglutination test, for the detection of Clostridium perfringens type A enterotoxin

An indirect haemagglutination (IH) test is described for the detection of Clostridium perfringens type A enterotoxin, produced by strains isolated from human cases of food poisoning and from contaminated food. Though no strict relationship could be observed between titers in the IH test and the time it took mice to die from the intravenous inoculation of mice (IIM test), results of the supernatants examined by both methods demonstrated that the IH test was more sensitive than the IIM one. No unspecific reaction was obtained in the IH with a negative control and the inhibitions of the IH and IIM tests by specific antiserum against C. perfringens enterotoxin showed that the IH test is very specific. The IH assay is recommended for its sensitivity and easy performance by less-equipped laboratories, by these and other data.