Immunofluorescence assay reactivity patterns of serum samples presenting indeterminate Western blot results for antibodies to HIV-1 and HTLV-I/II in Cordoba, Argentina.

Serum samples (n: 110) from blood donors and high risk individuals from Cordoba, Argentina with indeterminate HIV-1 and HTLV-I/II Wb profiles were studied for specific antibodies to HTLV-I/II and HIV-1 by indirect immunofluorescence assay (IFA) and for the presence or absence of HIV-1 and HTLV-I/II specific bands by Wb. This study was carried out in order to characterize their putative reactions with HIV-1 and HTLV-I/II proteins and to resolve the retrovirus infection status of these individuals. Results indicated that blood donors sera displaying indeterminate HIV-1 or HTLV-I/II Wb patterns were not immunoreactive to HTLV-I/II and HIV-1 on IFA. However, a high rate of indeterminate HIV-1 and HTLV-I/II Wb samples from high risk individuals had positive HTLV-I/II and HIV-1 IFA results respectively. Our study supports the growing evidence that HTLV-HIV indeterminate seroreactivity in low risk population is due to a cross reaction against nonviral antigens, and in high risk populations the indeterminate samples show serological cross-recognition between HIV-1 proteins and HTLV-I/II proteins on Wb. These results point out the necessity to investigate the HTLV-I/II reactivity in indeterminate HIV-1 samples and vice versa in order to confirm the diagnosis. Finally, this study shows the potential usefulness of IFA in elucidating the status of HIV-1 and HTLV-I/II infection of individuals with indeterminate Wb profiles, thus enabling resolution of retrovirus infection status.

[HTLV-I/II seroprevalence and risk factors associated with infection in a blood donor population in Córdoba, Argentina]. / Seroprevalencia de HTLV-I/II y factores de riesgo asociados a la infección en la población de donantes de sangre de Córdoba, Argentina.

In this study we have determined the seroprevalence of infections by HTLV-I/II in the blood donor population from the city of Córdoba. A total of 5476 blood donor sera were screened for HTLV-I/II antibodies by particle agglutination assay (PA) (SERODIA HTLV-I, Fujirebio INC, Tokyo, Japan). The reactive sera samples were confirmed by an "in house" indirect immunofluorescence assay (IFA). 14 out of 5476 blood donors studied were PA reactive and were confirmed positive by IFA, showing a prevalence of 0.26% (95% confidence interval: 0.126%-0.394%). All the positive samples, except one, met the criteria for HTLV-I. Although one HTLV-I infected donor was an intravenous drug abuser and two donors were born in highly endemic areas for HTLV-I, no specific risk factors were identified among the others. The demonstration that HTLV-I circulates in blood donor population of Córdoba, points out that the systematic screening of blood for HTLV-I/II antibodies must be implemented in the blood banks, in an attempt to prevent the spread of infections with this oncogenic virus in Argentina.

Seroprevalencia de HTLV-I/II y factores de riesgo asociados a la infección en la población de donantes de sangre de Córdoba, Argentina / HTLV-I/II seroprevalence and risk factors associated with infection in a blood donor population in Córdoba, Argentina

In this study we have determined the seroprevalence of infections by HTLV-I/II in the blood donor population from the city of Córdoba. A total of 5476 blood donor sera were screened for HTLV-I/II antibodies by particle agglutination assay (PA) (SERODIA HTLV-I, Fujirebio INC, Tokyo, Japan). The reactive sera samples were confirmed by an "in house" indirect immunofluorescence assay (IFA). 14 out of 5476 blood donors studied were PA reactive and were confirmed positive by IFA, showing a prevalence of 0.26 (95 confidence interval: 0.126-0.394). All the positive samples, except one, met the criteria for HTLV-I. Although one HTLV-I infected donor was an intravenous drug abuser and two donors were born in highly endemic areas for HTLV-I, no specific risk factors were identified among the others. The demonstration that HTLV-I circulates in blood donor population of Córdoba, points out that the systematic screening of blood for HTLV-I/II antibodies must be implemented in the blood banks, in an attempt to prevent the spread of infections with this oncogenic virus in Argentina.(AU)

Seroprevalencia de HTLV-I/II y factores de riesgo asociados a la infección en la población de donantes de sangre de Córdoba, Argentina / HTLV-I/II seroprevalence and risk factors associated with infection in a blood donor population in Córdoba, Argentina

In this study we have determined the seroprevalence of infections by HTLV-I/II in the blood donor population from the city of Córdoba. A total of 5476 blood donor sera were screened for HTLV-I/II antibodies by particle agglutination assay (PA) (SERODIA HTLV-I, Fujirebio INC, Tokyo, Japan). The reactive sera samples were confirmed by an "in house" indirect immunofluorescence assay (IFA). 14 out of 5476 blood donors studied were PA reactive and were confirmed positive by IFA, showing a prevalence of 0.26 (95 confidence interval: 0.126-0.394). All the positive samples, except one, met the criteria for HTLV-I. Although one HTLV-I infected donor was an intravenous drug abuser and two donors were born in highly endemic areas for HTLV-I, no specific risk factors were identified among the others. The demonstration that HTLV-I circulates in blood donor population of Córdoba, points out that the systematic screening of blood for HTLV-I/II antibodies must be implemented in the blood banks, in an attempt to prevent the spread of infections with this oncogenic virus in Argentina.

Seroprevalencia de HTLV-I/II y factores de riesgo asociados a la infección en la población de donantes de sangre de Córdoba, Argentina. / [HTLV-I/II seroprevalence and risk factors associated with infection in a blood donor population in Córdoba, Argentina]

In this study we have determined the seroprevalence of infections by HTLV-I/II in the blood donor population from the city of Córdoba. A total of 5476 blood donor sera were screened for HTLV-I/II antibodies by particle agglutination assay (PA) (SERODIA HTLV-I, Fujirebio INC, Tokyo, Japan). The reactive sera samples were confirmed by an [quot ]in house[quot ] indirect immunofluorescence assay (IFA). 14 out of 5476 blood donors studied were PA reactive and were confirmed positive by IFA, showing a prevalence of 0.26

(95

confidence interval: 0.126

-0.394

). All the positive samples, except one, met the criteria for HTLV-I. Although one HTLV-I infected donor was an intravenous drug abuser and two donors were born in highly endemic areas for HTLV-I, no specific risk factors were identified among the others. The demonstration that HTLV-I circulates in blood donor population of Córdoba, points out that the systematic screening of blood for HTLV-I/II antibodies must be implemented in the blood banks, in an attempt to prevent the spread of infections with this oncogenic virus in Argentina.

Evaluación de los equipos comerciales utilizados en los bancos de sangre de Córdoba para la detección de anticuerpos anti HTLV-I/II / Evaluation of commercial equipment used in blood banks in Córdoba for the detection of anti-HTLV-I/II antibodies

In order to assess the efficiency of currently used screening tests, Abbott HTLV-I/HTLV-II EIA, Vironostika HTLV-I/II Organon Teknika, Particle Agglutination (PA) assay Serodia Fujirebio Inc. (Tokyo, Japan) for HTLV-I/II antibody detection in blood donors samples, a panel of 100 sera from different blood banks of Córdoba city were studied. An "in house" indirect immunofluorescence assay (IFA) was used as reference test. The correlation rates were: 66 for Abbott HTLV-I/HTLV-II EIA, 97 for Vironostika HTLV-I/II Organon Teknika EIA and 99 for PA Serodia. Vironostika HTLV-I/II Organon Teknika EIA and PA Serodia assay proved to be more reliable for HTlV-I/II antibody screening in blood donors from Córdoba, yielding a very low rate of false positive results as compared with Abbot HTLV-I/HTLV-II EIA.(AU)

Evaluación de los equipos comerciales utilizados en los bancos de sangre de Córdoba para la detección de anticuerpos anti HTLV-I/II / Evaluation of commercial equipment used in blood banks in Córdoba for the detection of anti-HTLV-I/II antibodies

In order to assess the efficiency of currently used screening tests, Abbott HTLV-I/HTLV-II EIA, Vironostika HTLV-I/II Organon Teknika, Particle Agglutination (PA) assay Serodia Fujirebio Inc. (Tokyo, Japan) for HTLV-I/II antibody detection in blood donors samples, a panel of 100 sera from different blood banks of Córdoba city were studied. An "in house" indirect immunofluorescence assay (IFA) was used as reference test. The correlation rates were: 66 for Abbott HTLV-I/HTLV-II EIA, 97 for Vironostika HTLV-I/II Organon Teknika EIA and 99 for PA Serodia. Vironostika HTLV-I/II Organon Teknika EIA and PA Serodia assay proved to be more reliable for HTlV-I/II antibody screening in blood donors from Córdoba, yielding a very low rate of false positive results as compared with Abbot HTLV-I/HTLV-II EIA.

[Evaluation of commercial equipment used in blood banks in Córdoba for the detection of anti-HTLV-I/II antibodies]. / Evaluación de los equipos comerciales utilizados en los bancos de sangre de Córdoba para la detección de anticuerpos anti HTLV-I/II.

In order to assess the efficiency of currently used screening tests, Abbott HTLV-I/HTLV-II EIA, Vironostika HTLV-I/II Organon Teknika, Particle Agglutination (PA) assay Serodia Fujirebio Inc. (Tokyo, Japan) for HTLV-I/II antibody detection in blood donors samples, a panel of 100 sera from different blood banks of Córdoba city were studied. An "in house" indirect immunofluorescence assay (IFA) was used as reference test. The correlation rates were: 66% for Abbott HTLV-I/HTLV-II EIA, 97% for Vironostika HTLV-I/II Organon Teknika EIA and 99% for PA Serodia. Vironostika HTLV-I/II Organon Teknika EIA and PA Serodia assay proved to be more reliable for HTlV-I/II antibody screening in blood donors from Córdoba, yielding a very low rate of false positive results as compared with Abbot HTLV-I/HTLV-II EIA.

Evaluación de los equipos comerciales utilizados en los bancos de sangre de Córdoba para la detección de anticuerpos anti HTLV-I/II. / [Evaluation of commercial equipment used in blood banks in Córdoba for the detection of anti-HTLV-I/II antibodies]

In order to assess the efficiency of currently used screening tests, Abbott HTLV-I/HTLV-II EIA, Vironostika HTLV-I/II Organon Teknika, Particle Agglutination (PA) assay Serodia Fujirebio Inc. (Tokyo, Japan) for HTLV-I/II antibody detection in blood donors samples, a panel of 100 sera from different blood banks of Córdoba city were studied. An [quot ]in house[quot ] indirect immunofluorescence assay (IFA) was used as reference test. The correlation rates were: 66

for Abbott HTLV-I/HTLV-II EIA, 97

for Vironostika HTLV-I/II Organon Teknika EIA and 99

for PA Serodia. Vironostika HTLV-I/II Organon Teknika EIA and PA Serodia assay proved to be more reliable for HTlV-I/II antibody screening in blood donors from Córdoba, yielding a very low rate of false positive results as compared with Abbot HTLV-I/HTLV-II EIA.

Diarrhea and enteric emerging viruses in HIV-infected patients.

To evaluate the prevalence of enteric viruses and their possible association with diarrhea, 244 stool samples were collected from HIV-infected and uninfected patients with or without diarrhea (subgroups I-a, Ib, II-a, and II-b, respectively). Subjects were screened by polyacrylamide gel electrophoresis, latex agglutination, and enzyme immunoassays for rotaviruses, adenoviruses, picobirnaviruses, and astroviruses. Enteric viruses were found significantly more often in specimens from HIV patients (20%) than in specimens from uninfected HIV patients (0%) (p < 0.05). Picobirnavirus was detected in 14.63% of 82 HIV-infected patients with diarrhea, but it was detected neither in those without diarrhea (0%) (p < 0.05) nor in the groups of uninfected HIV subjects (0%) (p < 0.05). Nor could astrovirus (subgroups I-a [4.00%] versus subgroup I-b [5.26%],p > 0.05) or enteric adenovirus (subgroup I-a [1.22%] versus subgroup I-b [0%], p > 0.05) be linked to the diarrhea disorder in HIV-infected patients. Rotaviruses were not detected in any of the clinical subgroups studied. Enteric viruses were detected in 15 of 93 (16.13%) of the HIV-infected patients with CD4+ T cell count <200/microl and 3 of 19 (15.79%) of those HIV-infected individuals with a CD4+ T cell count 200-499/microl, showing no significant difference (p > 0.05). According to our data, unusual enteric viruses such as picobirnavirus, astrovirus, and enteric adenovirus occur in HIV-infected population in Córdoba, Argentina. However, only picobirnaviruses could be significantly associated with diarrhea in these patients.

Efficiency of indirect immunofluorescence assay as a confirmatory test for the diagnosis of human retrovirus infection (HIV-1 and HTLV-I/II) in different at risk populations

We compared the indirect immunofluorescence assay (IFA) with Western blot (Wb) as a confirmatory method to detect antibodies anti retrovirus (HIV-1 and HTLV-I/II). Positive and negative HIV-1 and HTLV-I/II serum samples from different risk populations were studied. Sensitivity, specificity, positive, negative predictive and kappa index values were assayed, to assess the IFA efficiency versus Wb. The following cell lines were used as a source of viral antigens: H9 ( HTLV-III b); MT-2 and MT-4 (persistently infected with HTLV-I) and MO-T (persistently infected with HTLV-II). Sensitivity and specificity rates for HIV-1 were 96.80% and 98.60% respectively, while predictive positive and negative values were 99.50% and 92.00% respectively. No differences were found in HIV IFA performance between the various populations studied. As for IFA HTLV system, the sensitivity and specificity values were 97.91% and 100% respectively with positive and negative predictive values of 100% and 97.92%. Moreover, the sensitivity of the IFA for HTLV-I/II proved to be higher when the samples were tested simultaneously against both antigens (HTLV-I-MT-2 and HTLV-II-MO-T). The overall IFA efficiency for HIV-1 and HTLV-I/II-MT-2 antibody detection probed to be very satisfactory with an excellent correlation with Wb (Kappa indexes 0. 93 and 0.98 respectively). These results confirmed that the IFA is a sensitive and specific alternative method for the confirmatory diagnosis of HIV-1 and HTLV-I/II infection in populations at different levels of risk to acquire the infection and suggest that IFA could be included in the serologic diagnostic algorithm.

Prevalence of antibody to human T cell lymphotropic virus types 1/2 among aboriginal groups inhabiting northern Argentina and the Amazon region of Peru.

We carried out a seroepidemiologic survey to define the prevalence of human T cell lymphotropic virus types 1/2 (HTLV-1/2) infections among aboriginal populations from isolated regions of northern Argentina and the Amazon region of Peru. Antibodies against HTLV were measured with agglutination tests and confirmed with by an immunofluorescence assay (IFA) and Western blotting. Five (6.94%) of 72 samples from the Tobas Indians in Argentina were positive by the IFA; two samples were typed as HTLV-1 (2.78%), two as HTLV-2 (2.78%), and one (1.39%) could not be typed because it had similar antibody titers against both viruses. No positive samples were found among 84 Andinos Puneños and 47 Matacos Wichis Indians. Seroprevalences of 2.50% (1 of 40) and 1.43% (1 of 70) for HTLV-1 were observed among Wayku and San Francisco communities in the Amazon region of Peru, and seroprevalences of 4.54% (1 of 22) and 2.38% (1 of 42) for HTLV-2 were observed among Boca Colorada and Galilea communities. No serologic evidence of human immunodeficiency virus (HIV) infection was found among the Indians tested. These results indicated the presence of HTLV-1 and HTLV-2 in the indigenous populations of Argentina and Peru. Moreover, the lack of HIV infection indicates that the virus has probably not yet been introduced into these populations.

Detection of picobirnavirus in HIV-infected patients with diarrhea in Argentina.

Diarrhea due to enteric pathogens is an important complication of advanced HIV infection. Picobirnaviruses are agents recently linked with human enteritis. In total, 197 fecal samples collected from HIV-infected and noninfected patients with and without diarrhea were investigated for the presence of rotavirus and picobirnavirus by polyacrylamide gel electrophoresis. Picobirnavirus was detected in 8.8% of 57 HIV-infected patients with diarrhea, but it was detected in neither those without diarrhea (p<.018) nor in the group of subjects uninfected with HIV (p<.022). All genomic electropherotypes of picobirnavirus strains had a wide pattern. Picobirnavirus genome segments varied in size between 2.4 and 2.7 and 1.6 and 1.9 kbp for the slow and fast migrating bands, respectively. Rotaviruses were not detected in any of the clinical groups studied. Two methods for the extraction of nucleic acid-phenol/chloroform and guanidinium thiocynate (GTC)/silica-were compared. Detection of picobirnavirus by polyacrylamide gel electrophoresis was 2.5 times more sensitive following guanidinium thiocynate RNA extraction. This investigation offers preliminary results about the circulation of picobirnavirus in HIV-infected patients in Córdoba, Argentina.

PIP: In 1988, a new group of viruses containing a bisegmented double-stranded RNA genome was described and named "picobirnavirus" (PBV). Viruses with similar properties have subsequently been found in fecal specimens collected from HIV-infected and noninfected patients with gastrointestinal symptoms in several countries. The present study used polyacrylamide gel electrophoresis (PAGE) to examine fecal specimens from 197 HIV infected and noninfected adults, with and without diarrhea, from Cordoba, Argentina, for rotavirus and PBV. PBVs were detected in the stools of 5 HIV-infected patients with diarrhea (8.8%), but in none of the other subgroups (HIV-positive patients without diarrhea, HIV-negative patients with diarrhea, HIV-negative patients without diarrhea). 3 of the 5 stool samples positive for PBV were also positive for intestinal parasites (mixed infection), but these parasites were found with equal frequency in HIV-infected patients without diarrhea. Rotaviruses were not detected in any of the subgroups. PBV genome segments varied in size between 2.4-2.7 and 1.6-1.9 kbp for the slow and fast migrating bands, respectively. PBV detection by the PAGE technique was 2.5 times more sensitive after guanidinium thiocyanate RNA extraction. Further research is required to determine the duration of excretion of PBVs in HIV-infected patients with diarrhea and understand the immune response to infection.

Loss maternally derived measles immunity in Argentinian infants.

BACKGROUND: Measles immunization of children at 1 year of age with a single dose of the current vaccine has successfully reduced measles incidence in Argentina. However, the optimal schedule of measles vaccination of young infants would balance the risk of early loss of maternal antibody in the majority of infants with the risk of primary vaccine failure because of passive measles immunity. This study is the first to document a significant association between loss of passive measles antibody and age among infants born in 1995 and 1996 in Córdoba City, Argentina. METHODS: This is a seroprevalence study of 340 infants to investigate the duration of transplacentally derived measles antibody, assayed by a neutralization test, during the first 8 months of age in Córdoba City, Argentina. RESULTS: The proportion with detectable neutralizing measles antibodies decreased from 85% at 1 month of age to 8% at 8 months of age. The simple logistic model with age (in weeks) as the only variable showed that the decline in the proportion of infants with a positive antibody titer was sharpest during the second and fifth months of age (6.6 and 6.8% per week during a 4-week period, respectively). CONCLUSIONS: These findings suggest that 80% of infants are susceptible to measles infection for at least 3 months before routine immunization at 12 months of age.

Culture amplification in human colon adenocarcinoma cell line (CaCo-2) combined with an ELISA as a supplementary assay for accurate diagnosis of rotavirus.

Culture amplification in colon adenocarcinoma cell line (CaCo-2) combined with enzyme immunoassay (Pathfinder ELISA) was developed as a supplementary tool for rotavirus diagnosis. One hundred and thirty stools in which results by polyacrylamide gel electrophoresis (PAGE) were in agreement with those obtained by ELISA were amplified in the CaCo-2 cell line. After the first passage 100% specimens were revealed as positive by ELISA. This result was confirmed by PAGE and direct electron microscopy (EM) which increased the rates of rotavirus detection up to 100% after the third and fifth cell passages, respectively. All of the amplified negative stools were confirmed as negative. Among discordant results, three of the eight specimens positive by ELISA but negative by PAGE were confirmed as true positive after the third cell passage. False positive ELISA results could be discarded when the samples were culture amplified and retested by the same ELISA. Using the CaCo-2 amplification-ELISA as supplementary assay, sensitivity and specificity were 1.000 and 0.953 for ELISA and 0.917 and 1.000 for PAGE, respectively. The combined CaCo-2 cell line amplification-immunoassay method proved to be suitable both to evaluate increase in sensitivity of newly developed rotavirus assays and for rotaviral amplification before antigen assays.

Kinetics study of human retrovirus antigens expression in T lymphocytic cell lines by indirect immunofluorescence assay.

Indirect immunofluorescence assay (IFA) is a well-accepted assay for the confirmation of human retrovirus infection. Fluctuations in HIV-1 antigen expression in infected E-B2 cells depending on several factors have been reported. Cells kept in log phase expressed the highest levels of viral antigen. Thus, we studied the time kinetics of IFA positivity in MT-2 (HTLV-I), MO-T (HTLV-II), CEM, and H9 (HIV-1) cell lines. Uninfected T cell line, HT, was used as nonspecific control. Reference HTLV-I/II and HIV-1 serum panels from the Centers for Disease Control and Prevention (CDC) were tested by conventional IFA procedure on slides of each cell line made on different days. On the second day after subculture, HTLV-I strongly positive sera reacted on MT-2 and MO-T cells with a bright pericytoplasmic fluorescence pattern. Weakly positive sera showed a faint staining from the fifth day on, when all the sera showed the highest degree of fluorescence. With HIV-1 cell lines, sera predominantly reacted with a diffuse cytoplasmic pattern, although some sera showed a granular and pericytoplasmic capping staining. The highest degree of fluorescence was found at 3-5 days after subculture. We demonstrated that the sensitivity of the IFA for the detection of antibodies against human retroviruses depended on the day when the slides were assayed and on the serum antibody titer. The fifth day was the most appropriate for HTLV-I/II and HIV-1/H9 systems, whereas for HIV-1/CEM, the fourth day was better. Furthermore, the intensity of the immunofluorescence pattern differed with the antibody titers and the level of antigens expressed on the four cell lines studied. The IFA, improved in our laboratory, proved to be very sensitive, specific, and rapid and could be used as a supplementary/confirmatory assay for retrovirus infection.

Immunoglobulin M antibody response to measles virus following natural virus infection, primary vaccination, and reexposure to the virus.

Evaluation of the measles virus ELISA kit (Merck) to detect specific IgM as an indicator of primary measles antibody response was carried out. A modification of the manufacturer's cutoff value interpretation was introduced to allow for equivocal results in addition to positive and negative ones. With this modification, the test assayed gave an overall reproducibility of 96.16%. The IgM seropositivity rate for seroneutralization-confirmed measles cases was 100% for naturally infected measles subjects and 90% for primary measles vaccinated subjects. Individuals with positive neutralizing antimeasles antibodies in close contact with a confirmed measles case gave the following measles IgM ELISA results: 54.54% negative, 9.09% positive, and 36.36% equivocal, showing a booster with IgM antibody response on reexposure to the virus. Positive subjects with neutralizing antimeasles antibodies without recent contact with a measles case gave negative IgM results. IgM seropositivity was strongly associated with IgG seroconversion and clinical measles (p < 0.0001). The technique assayed performed adequately for the confirmation of both measles natural infection and primary vaccination and for the differentiation of primary and secondary antibody response, taking into account the modification in the cutoff value interpretation introduced and providing that the serum samples are obtained between days 5 and 30 after onset of rash.

Rapid vertical agarose: silver stain detection of rotavirus.

Human rotaviruses (HRV) are the most important etiologic agents of acquired diarrhea in infants and young children worldwide. Therefore, the early diagnosis is essential for effective patient management and infection control. We have developed a rapid, simple technique for the diagnosis of rotavirus based on the sensitive detection of rotavirus double-stranded RNA genome segments separated in vertical agarose gels and developed by silver staining (AGE-SS). This method also has the ability to detect differences in the electrophoretic mobility of RNA bands among group C rotaviruses, reovirus, and group A rotaviruses. The results indicate that this assay is as sensitive and specific as the polyacrylamide gel electrophoresis and silver stain method (PAGE/SS) and it could be applied on large scale for the screening of stool suspected of rotaviral diarrhea. This assay does not need sophisticated equipment and the cost per sample is minimal compared with other available assays.