Evaluation of three serological tests for the detection of human plague in northeast Brazil

The passive haemagglutination (PHA) test, enzyme-linked immunosorbent assay (ELISA) and the dot enzyme-immunosorbent assay (DOT-ELISA) were used to detect the levels of IgG antibodies against the Fraction 1 (F1) antigen of Yersinia pestis in sera of plague-infected patients from Northeast Brazil. Twenty three selected PHA-positive sera of subjects with bacteriological confirmation of plague were also positive in the DOT-ELISA but only 19 were detected by the conventional ELISA technique. Another group of 186 serum samples from subjects diagnosed as plague-infected by clinical and epidemiological parameters, but PHA-negative, were screened with DOT-ELISA and 11 gave positive results. The specificity of the assays on the serological detection of plague was confirmed in inhibition tests using purified F1 antigen. These results suggest that DOT-ELISA can be an useful, simple and more sensitive alternative for the serodiagnosis of plague in Northeast Brazil.

Detection of cytomegalovirus in urine of HIV-infected patients by DNA-DNA hybridization comparison with virus isolation, immunofluorescence and immunoperoxidase

Immunofluorescence and immunoperoxidase test directed against early viral antigens, and DNA-DNA hybridization were compared with viral isolation for their abilities to detect Cytomegalovirus (CVM) in the urine of 89 HIV infected patients. From the 100 urine samples collected, 70 were found positive by at least one method. Considering viral isolation as the "gold standard" technique, immunofluorescence and immunoperoxidase had a sensitivity of 92.3% and88% respectively, with a specificity in both cases of 95%. DNA-DNA hybridization showed a sensitivity of 90% but with lower (60%) specificity. All of the three assays were effective in detecting CVM from urine and the technical advantage of each is discussed.

Rapid in vitro detection of HIV-1-specific antibody secretion by cells-culture with virus antigens

The present report describes an alternative method for in vitro detection of HIV-1 -specific antibody secretion in 24h of culture employing as stimulant of peripheral blood mononuclear cells the disrupted inactivated whole virus adsorbed onto microwells in a commercial ELISA kit plates. The results obtained from this technique have showed high sensitivity and specificity since it was capable of detecting HIV-1 infection early after birth. There were neither false-positivity nor false-negativity when blood samples obtained from HIV-1 seronegative asymptomatic individuals, and HIV-1 seropositive adult patients were analized. This rapid, low cost, simple, highly sensitive and specific assay can be extremely useful for early diagnosis of pediatric HIV infection.

Detection of Babesia bigemina infection: use of a DNA probe - a review

The development of a repetitive DNA probe for Babesia bigemina was reviewed. The original plasmid (p(Bbi)16) contained an insert of B. bigemina DNA of approximately 6.3 kb. This probe has been evaluated for specificityand analytical sensitivity by dot hybridization with isolates from Mexico, the Caribbean region and Kenya. A partial restriction map has been constructed and insert fragments have been subcloned and utilized as specific DNA probes. A comparison of 32P labelled and non-radioactive DNA probes was presented. Non-radioctive detection systems that have been used include digoxigenin dUTP incorporation, and detection by colorimetric substrate methods. Derivatives from the original DNA probe have been utilized to detect B. bigemina infection in a) experimentally inoculated cattle, b) field exposed cattle, c) infected Boophilus microplus ticks, and d) the development of a PCR amplification system.

T lymphocytes and iron overload: novel correlations of possible significance to the biology of the immunological system

This paper is written in the context of our changing preception of the immunological system as a system with possible biological roles exceding the prevailung view of a system concerned principally with the defense against external pathogens. The view discussed here relates the immunological system inextricably to the metabolism of iron, the circulation of the blood and the resolution of the evolutionary paradox created by oxygen and iron. Indirect evidence for this inextricable relationship between the two systems can be derived from the discrepancy between the theoretical quasi-impossibility of the existence of an iron deficiency state in the adult and the reality of the WHO numbers of people in the world with iron deficiency anemia. With mounting evidence that TNF, IL-1, and T lymphocyte cytokines affect hemopoieisis and iron metabolism it is possible that the reported discrepancy is a reflection of that inextricable interdependence between the two systems in the face of infection. Further direct evidence for a relationship between T cell subset numbers and iron metabolism is presented from the results of a study of T cell populations in patients with hereditary hemochromatosis. The recent finding of a correlation between low CD8+ lymphocite numbers, liver demage associated with HCVpositivity and severity of iron overload in B-thalassemia major patients (umpublished data of RW Grandy; P. Giardina, M. Hilgartner) concludes this review.

Visceral leishmaniasis in Teresina, state of Piauí, Brazil: preliminary observations on the detection and transmissibility of canine and sandfly infections

A Leishmania donovani-complex specific DNA probe was usedto confirm the widespread dissemination of amastigotes in apparently normal skinof dogs with canine visceral leishmaniasis. When Lutzomyia longipalpis were fed on abnormal skin of five naturally infected dogs 57 of 163 (35 per cent) fliesbecame infected: four of 65 flies (6 per cent) became infected when fed on apparently normal skin. The bite of a single sandfly that had fed seven days previouslyon a naturally infected dog transmitted the infection to a young dog from a non-endemic area. Within 22 days a lesion had developed at the site of the infectivebite (inner ear): 98 days after infection organisms had not disseminated throughout the skin, bone marrow, spleen or liver and the animal was still serologically negative by indirect immunofluorescence and dot-enzyme-linked immunosorbent assay. When fed Lu. longipalpis were captured from a kennel with a sick dog known to be infected, 33 out of 49 (67 per cent) of flies contained promastigotes. In contrast only two infections were detected among more than 200 sandflies captured in houses. These observations confirm the ease of transmissibility of L.chagasi from dog to sandfly to dog in Teresina. It is likely that canine VL is the major source of human VL by the transmission route dog-sandfly-human. the Lmet2 DNA probe was a useful epidemiological tool for detecting L. chagasi in sandflies.

Comparative evaluation of a simple and sensitive assay for detection of orthomyxo and paramyxoviruses

Studies were done to evaluate comparatively the traditional HA assay and a more recently introduced lectin-neuraminidase (LN) methodologyin search of a simple and sensitive assay for virus detection during laboratorial diagnosis. The results proved the value of LN assay as a sensitive methodologyfor detection of virus particles, presenting results at least equal to those obtained by HA (hemagglutination) assay, with significant values of accumulated frequencies for LN/HA factors (ratios between LN and HA titers) higher than two. The accumulated values of frequencies for LN/HA factors as high as four were very significant, 72.7 (per cent) for influenzavirus and 60.7 (per cent) for Newcastle disease virus (NDV), moreover accumulated frequencies for LN/HA factors even as high as 32 were due to influenzavirus (45.4 per cent) and NDV (7.2 per cent) samples. After the storage period, most of those concentraded samples that even did not present HA titers could be detected through LN assay, demonstrating a lower threshold for virus detection.

Human papillomavirus detection in genital lesions by in situ hybridization and ultrastructural observations

Detection of papillomavirus DNA in sity hybridization technique was perfomed in 29 symptomatic patients (6 males and 23 females) during the period of 1989-1991 at the Clinic for Sexually Transmitted Diseases, Universidade Federal Fluminense, State of rio de Janeiro. All the male patients had condyloma acuminata. Only HPV 6/11 were found in these lesions. Clinical features inthe female patients included vulvar condyloma acuminata, bowenoid populosis, flat cervical condyloma, cervical condyloma acuminatum and cervical intraepithelialneoplasia grade II (CIN II). We also found cases of condyloma acuminata associated to vulvar intraepithelial neoplasia grade III (VIN III), as well as to vaginal invasive carcinoma. HPV 6/11 and 16/18 were found in vulvar condyloma acuminata. Mixed infection by 6/11-16/18 HPV were also seen in these lesions as well as in the patient who had cervical condyloma acuminatum. HPV 16/18 were found in the condyloma acuminatum plus VIN III and in the CIN II lesions. We have found HPV31/33/51 in the specimen of condyloma acuminatum plus invasive carcinoma. In order to investigate the ultrastructural aspects of HPV infection in genital tissue, the biopsies of three female patients were observed under electron microscope.Mature virus particles were found in the cells of a condyloma acuminatum as wellas in the condyloma acuminatum plus invasive carcinoma case. In another sample, chromosome breakages were found in the nuclei of the infected cells although no viral particles were observed.

Use of molecular probes and PCR for detection and typing of Leishmania - a mini-review

The use of molecular tools to detect and type Leishmania species in humans, reservoirs or sandflies has been pursued using different approaches. The polymerase chain reaction provided sensitivity to case this task, since the use of hybridization procedures alone employing specifics probes is hampered due to the low detection limit. In this report, we describe the different molecular targets used in our laboratory, aiming at the detection and specific typing of these protozoa. Different kits based on hybridization assays and PCR amplification using kinetoplast and nuclear targets are described and the results obtained from their use are reported.