Exploration of an Efficient Simultaneous Molecular Detection Method of HIV, HCV, and Syphilis from a Single Dried Blood Spot / 生物医学与环境科学（英文）

Objective@#The aim of the present study was to evaluate the performance of the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA using one dried blood spot (DBS) as an alternative sample to plasma.@*Method@#A total of 571 paired DBS/plasma samples were collected from men who have sex with men (MSM) and injection drug users (IDUs), and serological and molecular assays were performed. Using plasma results as the reference standard, the performance of DBS tests for HIV-1 RNA, HIV-1 DNA, and HCV RNA was evaluated. Pearson's correlation coefficients and Bland-Altman analysis were performed to assess the correlation and concordance between DBS and plasma.@*Results@#Among paired plasma/DBS samples with detectable HIV-1 RNA and HCV RNA, five samples (5/32) were not detectable in DBS, while measurable HIV-1 RNA levels were present in plasma (1.44 to 3.99 log @*Conclusion@#The performance of the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA using one DBS was acceptable. DBS, as an alternative sample to plasma, may be a viable option for the simultaneous detection of HIV-1 RNA, HIV-1 DNA, and HCV RNA in resource-limited settings or for individuals living in areas that are difficult to access.

Hepatitis C viral load in HCV-monoinfected and HCV/HIV-1-, HCV/HTLV-1/-2-, and HCV/HIV/HTLV-1/-2-co-infected patients from São Paulo, Brazil

ABSTRACT Co-infections of hepatitis C virus (HCV) and either human immunodeficiency virus type 1 (HIV-1), human T-cell lymphotropic virus type 1 (HTLV-1) or type 2 (HTLV-2) have been described as having an impact on HCV viremia and subsequent disease progression. HCV load in serum samples from 622 patients (343 males, 279 females; median age 50.8 years) from São Paulo/southeast Brazil was analyzed using the Abbott Real Time HCV assay (Abbott Molecular Inc., IL, USA). Samples were obtained from HCV-monoinfected (n = 548), HCV/HIV-1- (n = 41), HCV/HTLV-1- (n = 16), HCV/HTLV-2- (n = 8), HCV/HIV/HTLV-1- (n = 4), and HCV/HIV/HTLV-2-co-infected (n = 5) patients, and results were compared among the groups and according to sex. The median HCV load in HCV-monoinfected patients was 5.23 log10 IU/mL and 0.31 log10 higher in men than in women. Increases in viral load of 0.51 log10, 0.54 log10, and 1.43 log10 IU/mL were detected in HCV/HIV-1-, HCV/HTLV-1- and HCV/HIV/HTLV-1-co-infected individuals, respectively, compared with HCV-monoinfected counterparts. In contrast, compared to HCV/HIV co-infected patients, HCV/HTLV-2-co-infected patients had an HCV load of 5.0 log10 IU/mL, whereas HCV/HIV/HTLV-2-co-infected patients had a median load 0.37 log10 IU/mL lower. Significant differences in HCV loads were detected, with males and HCV/HIV-1- and HCV/HIV/HTLV-1-co-infected patients presenting the highest values. Conversely, females and HCV/HTLV-2-co-infected patients exhibited lower HCV loads. Overall, HCV viremia is increased in HIV and/or HTLV-1-co-infection and decreased in HTLV-2 co-infection.

Optimización de recursos para determinar la carga viral de HIV-1 en un país con pocos recursos / Optimizing resources to reduce costs to determine HIV viral load in limited resources settings

Resumen Introducción. Las metas globales para controlar la epidemia de HIV contemplan que la carga viral sea indetectable en 90 % de las personas en tratamiento. El costo de la medición de la carga viral en lotes de muestras puede reducirse y, así, aumentar la cobertura cuando los recursos son limitados; sin embargo, su eficacia disminuye al aumentar la prevalencia del fracaso del tratamiento antirretroviral. Objetivo. Evaluar estrategias para disminuir la proporción de pacientes con fracaso del tratamiento antirretroviral en los lotes de muestras y, de esta manera, aumentar el ahorro en las pruebas de carga viral. Materiales y métodos. Las estrategias evaluadas fueron: a) la organización de los lotes de muestras según el esquema de tratamiento antirretroviral, y b) la exclusión de aquellos pacientes con antecedente reciente de fracaso del tratamiento antirretroviral, aquellos con menos de 12 meses de tratamiento antirretroviral y aquellos sin tratamiento antirretroviral previo. Los resultados de los lotes se compararon con los resultados individuales. Resultados. El valor diagnóstico negativo fue similar para los pacientes con esquema de primera línea (100,0 %; IC95% 99,5-100,0) o de segunda línea de tratamiento (99,4 %; IC95% 96,9-99,9). La incidencia del fracaso del tratamiento antirretroviral fue menor en los pacientes con tratamiento de primera línea (p<0,01), lo cual permitió un mayor ahorro en las pruebas de laboratorio en este grupo (74,0 %; IC95% 71,0-76,7) que en los pacientes con tratamiento de segunda línea (50,9 %; IC95% 44,4-57,3) (p<0,01). Conclusión. La selección de las muestras que se incluyeron en los lotes para determinar la carga viral del HIV según el tipo de esquema de tratamiento, permitió maximizar el porcentaje de ahorro en pruebas de laboratorio.

Abstract Introduction: HIV viral load testing is a key factor to evaluate the accomplishment of the UNAIDS target of 90% of viral suppression among people receiving antiretroviral therapy. Pooled samples are a potentially accurate and economic approach in resource-constrained settings, but efficiency can be negatively affected by high prevalence rates of virological failure. Objective: Strategies were assessed to increase the relative efficiency of pooled HIV viral load testing in resource-constrained settings. Materials and methods: We evaluated two strategies: a) plasma samples were not included in pools if patients had <12 months on antiretroviral therapy, patients had previous viral load >1,000 copies/ml, or were antiretroviral therapy naïve patients, and b) plasma pools were organized separately for first and second-line antiretroviral therapy regimens. Individual viral load tests were used to compare pooled results. Results: Negative predictive values were similar for patients on first (100.0%; 95% CI 99.5 to 100.0) and second-line antiretroviral therapy regimens (99.4%; 95% CI 96.9 to 99.9). However, the incidence of virological failure among individuals on first-line antiretroviral therapy was lower than second-line antiretroviral therapypatients (p <0.01), resulting in greater savings in laboratory tests in patients on first-line antiretroviral therapy (74.0%; 95% CI 71.0 to 76.7) compared with the group of patients on second-line antiretroviral therapy (50.9%; 95% CI 44.4 to 57.3) (p<0.01). Conclusion: Selecting the samples to be included in the pools and selecting the pools according to ART regimens are criteria that could lead to decreased spending on laboratory tests for HIV viral load determination in resource-constrained settings.

Sensibilidad del equipo Cobas AmpliScreenTM HIV-1 Test, v1. 5, para la detección de HIV-1 / Sensitivity of the COBAS AmpliScreenTM HIV-1 Test v1.5 for HIV-1 detection

Las técnicas de amplificación de ácidos nucleicos (NAT) se incorporaron en los bancos de sangre para reducir el riesgo residual de transmisión de infecciones por vía transfusional. La cocirculación de distintas variantes del HIV-1 en Argentina indica la necesidad de evaluar la sensibilidad de los ensayos serológicos y moleculares disponibles para su detección. En este trabajo se evaluó la sensibilidad del equipo COBAS AmpliScreenTM HIV-1 Test, versión 1.5 (Roche), para detectar ARN viral en plasmas de individuos infectados con HIV-1 de Argentina. Los resultados demuestran que esta técnica tiene una alta sensibilidad para detectar ARN de HIV-1 en las condiciones ensayadas: para ensayo de mini-pooles (pooles ≥ 50 copias de ARN/ml), la sensibilidad fue ≥ 92 %, y para procedimiento estándar (plasmas ≥ 207 copias de ARN/ml), la sensibilidad fue 100 %. Además, la técnica COBAS AmpliScreenTM HIV-1 Test, versión 1.5 (Roche), es adecuada para la detección de las variantes de HIV-1 prevalentes

The introduction of nucleic acid amplification techniques (NAT) in blood banks was intended to reduce the residual risk of transfusion-transmitted infections. Co-circulation of a great diversity of HIV-1 variants in Argentina portrays the need to assess the sensitivity of serological and molecular assays available for their detection. In this study, we evaluated the sensitivity of the COBAS AmpliScreenTM HIV-1 Test, version 1.5 (Roche) for the detection of HIV-1 RNA in plasma samples of infected individuals from Argentina. The results of this study reveal that this technique has high sensitivity for the detection of HIV-1 RNA under assay conditions: using mini-pool testing, pools ≥ 50 RNA copies per ml achieved ≥ 92 % sensitivity, whereas in the standard procedure, samples ≥ 207 RNA copies/ ml achieved 100 % sensitivity. Moreover, the COBAS AmpliScreenTM HIV-1 Test, version 1.5 (Roche) is suitable for detecting prevailing HIV-1 variants

A robust HIV-1 viral load detection assay optimized for Indian sub type C specific strains and resource limiting setting

BACKGROUND: Human Immunodeficiency Virus Type 1 (HIV-1) viral load testing at regular intervals is an integral component of disease management in Acquired Immunodeficiency Syndrome (AIDS) patients. The need in countries like India is therefore an assay that is not only economical but efficient and highly specific for HIV-1 sub type C virus. This study reports a SYBR Green-based HIV-1 real time PCR assay for viral load testing and is designed for enhanced specificity towards HIV-1 sub type C viruses prevalent in India. RESULTS: Linear regression of the observed and reference concentration of standards used in this study generated a correlation coefficient of 0.998 (p<0.001). Lower limit of detection of the test protocol was 50 copies/ml of plasma. The assay demonstrated 100% specificity when tested with negative control sera. The Spearman coefficient of the reported assay with an US-FDA approved, Taqman probe-based commercial kit was found to be 0.997. No significant difference in viral load was detected when the SYBR Green based assay was used to test infected plasma stored at -20°C and room temperature for 7 days respectively (Wilcoxon signed rank test, p=0.105). In a comparative study on 90 pretested HIV-1 positive samples with viral loads ranging from 5,000 - 25,000 HIV-1 RNA copies/ml and between two commercial assays it was found that the later failed to amplify in 13.33% and 10% samples respectively while in 7.77% and 4.44% samples the copy number values were reduced by >0.5 log value, a figure that is considered clinically significant by physicians. CONCLUSION: The HIV-1 viral load assay reported in this study was found to be robust, reliable, economical and effective in resource limited settings such as those existing in India. PCR probes specially designed from HIV-1 Subtype C-specific nucleotide sequences originating from India imparted specificity towards such isolates and demonstrated superior results when compared to two similar commercial assays widely used in India.

Individual donor nucleic acid testing for blood safety against HIV-1 and hepatitis B and C viruses in a tertiary care hospital.

Background. In July 2010, we started universal individual donor nucleic acid testing (ID-NAT) at our blood bank. This test simultaneously detects human immunodeficiency virus-1 (HIV-1), hepatitis B virus (HBV) and hepatitis C virus (HCV) in samples of donor blood. We continued to do the enzymelinked immunosorbent assay (ELISA) test for these agents, as per the guidelines of the Drug Controller General of India. We assessed the impact of ID-NAT in preventing transfusionassociated transmission of viruses. Methods. We used fourth generation ELISA to screen blood samples of all voluntary and replacement blood donors. ID-NAT was done by transcription-mediated amplification (TMA). Results. Of the 18 356 donors, ID-NAT could not be performed on 2 samples which were inadequate. Of the 18 354 donors tested by both ID-NAT and fourth generation ELISA, 7 were found to be NAT-positive but ELISA-negative (NAT yield) for HBV and HCV. The prevalence of NAT yield cases among routine donors was 1 in 2622 donations tested (0.038%). Since we supply blood as components (packed red cells, fresh frozen plasma and platelet concentrate), these 7 units of blood would have yielded 21 components and hence 21 patients could have been infected with HBV and HCV viruses. Conclusion. In the vast majority of blood units tested, the results of ELISA and ID-NAT for HIV-1, HBV and HCV were concordant. ID-NAT did detect the presence of viruses missed by ELISA in some blood units. It widespread use in blood banks would ensure safer blood transfusion.

[Multiplex RT-PCR assay for detection of Co-infection HIV-1 and HCV viruses in plasma samples]

HIV-1 and HCV infections especially in co-infected forms are among the most important infections transferred during blood transfusion. The screening of the blood products is valuable for preventing the transmission of infections. The aim of this study was to evaluate multiplex RT-PCR assay for detection of Co-infection HIV-1 and HCV Viruses in plasma samples. This laboratory study was done to evaluate the use of multiplex RT-PCR assay for simultaneous detection of HIV-1 and HCV genomes in plasma samples. The amplified genomes were detectable in 3% agarose gel base on difference in the numbers of nucleotides. The sensitivity and specificity of this assay was determined on healthy and infected subjects whome simultanously exhibit HIV-1 and HCV co-infection using plasma samples. The specificity results showed that the primers used in this assay have no interaction with each other and other possible interfering agents. The clinical sensitivity and specificity of the assay has been considered as 90% and 100%, respectively. Multiplex RT-PCR can be used for screening of blood donors due to high sensivity and specificity

Assessment of a self-deferral form for screening blood donors, Chiang Mai University Hospital, Thailand.

A self-deferral form has been used to screen Chiang Mai University Hospital blood donors and was improved in 2005. It has never been evaluated. The study aimed to assess the self-deferral form procedures in detecting infected donors. Sera from 5,083 donors, who passed the self-deferral screening form, were tested with the routine immuno-assays (serology) for HIV 1 and 2 antibodies, P24 antigen, HCV antibodies, HBV surface antigen, and syphilis. Antibody negative sera were also tested individually with the the Procleix Ultrio Assay for HIV-1 DNA, HCV RNA, and HBV DNA. The donors who had discrepant results between serology and NAT were evaluated with additional tests, including a more sensitive Alternative Nucleic Acid Test, AntiBcore IgM, AntiBcore IgG, HBsAg and Anti HBs. Among 5,083 donors, 331 (6.5%) had at least one positive marker. In multiple logistic regression analysis, the statistically significant factors (adjusted odds ratio and 95% CI) for infection were age 30 years or below [1.45 (1.03, 2.03)], male gender [2.73 (1.64, 4.56)], primary school or lower education [1.56 (1.09, 2.23)], first-time donation [1.82 (1.25, 2.67)], and frequent donation [0.80 (0.70, 0.92)]. The safest donors were females, older than 30 years, with an education more than primary school, and frequent donation. Because of missing responses to some sensitive questions, there remains a need for further improvement of the self-deferral form.

Evidence for lower CD4+ T cell and higher viral load in asymptomatic HIV-1 infected individuals of India: implications for therapy initiation.

PURPOSE: We have earlier documented that the south Indian population had lower CD4 counts. The aim of this study was to investigate a previous suggestion on a new CD4+ T cell cut off and association with HIV-1 RNA levels for decision on anti retroviral therapy in India (south). METHODS: We evaluated a new methodology i.e., artus real-time PCR and CD4+ T cell count by Guava EasyCD4 system. From 146 HIV infected individuals seen at a tertiary care centre, blood was collected for CD4+ T cell and HIV-1 RNA estimation. RESULTS: The receiver operating characteristic curve cut off value for the CD4 counts to distinguish between CDC clinical categories A and B was 243 cells/microL, and to distinguish B and C was 153 cells/microL. The RNA level that differentiated CDC A and B was 327473 RNA copies/mL, while for CDC B and C was 688543 copies/mL. There was a significant negative correlation (r = -0.55, P + T cell counts in HIV infected individuals. CONCLUSIONS: A majority with CD4 counts of 201-350 cells/microL in our population had higher viral load than the treatment threshold suggested by the International AIDS society and the above two methodologies are useful in monitoring HIV infections.

The use of dried blood spots on filter paper for the diagnosis of HIV-1 in infants born to HIV seropositive women.

Polymerase chain reaction (PCR) is the most sensitive test to diagnose HIV-1 infection among infants born to HIV seropositive mothers. The purpose of this study was to evaluate the use of dried blood spot (DBS) specimens for PCR and to compare it with whole-blood stored in tubes for HIV-1 DNA PCR. Five hundred and seventy-seven whole-blood infant samples were tested using HIV-1 qualitative in-house nested DNA PCR. Three hundred and fifty-nine samples were from infants at 48 hours of birth and 218 samples at second month. All positive samples tested from whole-blood and every fifth negative sample were coated onto filter paper. DNA was extracted from the filter paper and was amplified using in-house nested PCR. Among the whole-blood samples tested using HIV-1 DNA PCR, 19 of 359 (5.29%) samples were HIV-1 positive and 340 (94.7%) were negative at 48 hours of birth. At second month, 19 (8.7%) of the 218 samples were positive and 199 (91.2%) were negative. Using dried filter paper, 18 samples (95%) tested positive from 19 positive samples (using whole-blood) and 1 tested negative at 48 hours of birth. The 68 negative samples tested using whole-blood were also negative in the DBS test (sensitivity 95% and specificity 100%). At second month, 19 were positive and 40 samples (every fifth sample of 199) were negative (sensitivity and specificity, 100%). PCR performed using DNA extracted from filter paper permits the diagnosis of HIV-1 infection among infants born to HIV-1 seropositive mothers. This assay is simple, rapid, sensitive and specific and can be used in resource limited settings.

Genetic basis of HIV-1 resistance and susceptibility: an approach to understand correlation between human genes and HIV-1 infection.

HIV infection is the serious medical and public health issue of present generation. By 2005, it has already infected a cumulative total of more than sixty million people worldwide and the number of HIV positive cases are rising day by day. India is currently estimated to have about 5.1 million infected persons with HIV-1 or AIDS (second only to South Africa) and this number could increase to 24 million in the next ten years. This pandemic situation of the AIDS stimulated a plethora of longitudinal cohort studies which are designed to document medical heterogeneity as well as to mitigate the factors that regulate the HIV-1 infection, disease progression and the immune defenses. In recent years these genetic studies have led to the discovery of various MHC and non MHC encoded genes, which directly or indirectly influence the susceptibility and resistance to HIV infection and AIDS. These genes and their mutated forms and their products which play a major role in determining the susceptibility or resistance to HIV-1 infection and AIDS. These genes have been categorized into MHC or non MHC encoded genes. The MHC encoded genes which determine HIV resistance or susceptibility are HLA-B57, HLA-B58, HLA-B27, HLA-Bw4 and HLA-A11 in Southeast Asians. On the other hand, non MHC encoded genes are CCR5, CCR2, RANTES, CXCL12, CXCR6, CCL3L1, Interleukin-10 (IL-10), and interferon gamma. The site specific mutations in these genes determine the susceptibility or resistance to HIV-1 infection and AIDS. In future the study of host genes in relation to HIV-1 infection may provide the researchers to develop newer chemotherapeutic approaches to prevent or cure HIV-1 infection effectively.

Nucleic acid amplification technology Screening for hepatitis C virus and human immunodeficiency virus for blood donations

To investigate the performance of the commercial Roche COBAS AmpliScreen assay, and demonstrate whether the COBAS AmpliScreen human immunodeficiency virus-1 [HIV-1] test, v1.5, and COBAS AmpliScreen hepatitis C virus [HCV] v 2.0 for screening for HIV-1 and HCV RNA in the donated blood units from which plasma mini pools were collected, by nucleic acid amplification technology [NAT], could detect the positive pools and reduce the risk of transmission of infections for those routinely tested by serological assays. The study was performed on 3288 plasma samples collected from blood donors in a period of 13 months, from August 2004 to August 2005, at Al-Hada Armed Forces Hospital, Molecular Pathology Laboratory, Taif, Kingdom of Saudi Arabia. The samples were tested by the reverse transcriptase polymerase chain reaction [RT-PCR] after RNA extraction [this represents the major method in NAT assays], in parallel with the routine serological testing to detect qualitatively for HIV-1 and HCV. The NAT assays that include an automated COBAS AmpliPrep system for RNA extraction and COBAS Amplicor Analyzer using AmpliScreen kits for RT-PCR assays, and the routine serological screening assays for the detection of the HIV-1 and HCV RNA in the plasma samples from the blood donors have shown to be a reliable combination that would meet our requirements. The collected data further confirms the results from the serological assays and enables us to decrease the residual risk of transmission to a minimum with the finding of no seronegative window period donation. The results demonstrate that out of 3288 samples, the percentages of RT-PCR [NAT] negative blood donations that were also confirmed as seronegative were 99% for HCV, and 99.1% for HIV-1. The modified combined systems [automated COBAS AmpliPrep system for RNA extraction and COBAS Amplicor Analyzer using AmpliScreen kits for RT-PCR assays] for NAT screening assays has allowed the release of all blood donations supplied in the specified period of the study with no seronegative window period donations. This facilitates keeping the residual risk of transmission of HIV-1 and HCV to its minimum through blood transfusion

Coinfection with epstein barr virus in north Indian patients with HIV/AIDS.

Acquired immunodeficiency syndrome (AIDS) has emerged as a serious health problem in India. Although tuberculosis appears to be the commonest opportunistic infection, studies pertaining to opportunistic viruses are scant In the present study co infection with EBV was evaluated in patients with AIDS using a highly sensitive polymerase chain reaction besides anti Zebra antibody assays for diagnosis of an active EBV infection in 37 patients of full-blown AIDS and 32 healthy seropositives. Thirty healthy laboratory workers were used as controls. Out of 37 patients with AIDS, 12 were positive for anti Zebra antibodies and 23 were positive for EBV by the PCR reaction. Out of the 32 seropositives, 3 were positive for anti Zebra antibodies and 4 were positive by PCR assay. The difference between seropositives and AIDS was significant (p < .05). None of the controls were positive for an active EBV infection. It is concluded that active EBV infection is an important co infection in patients with AIDS and may contribute significantly to morbidity and mortality in these patients.

Application of laboratory methods for estimation of HIV-1 incidence.

Estimating HIV-1 incidence (rate of new HIV-1 infections) in various populations is important to understand the current status of transmission dynamics, identify high-risk populations, monitor prevention efforts and target resources on programmes that are most effective in reducing transmissions. Recent developments in our ability to detect and distinguish recent and longterm HIV-1 infections using laboratory tests have made the measurement of HIV-1 incidence realistic and practical. These approaches most commonly rely on the properties of early HIV-1 antibodies after seroconversion as characterized by their levels, antibody avidity/affinity or antibody classes/subclasses or epitope specificity. The sensitive/less-sensitive testing strategy provided simple laboratory tools to detect recent seroconversion in a cross-sectional population. These assays are based on differences in antibody titres in recent versus long-term infections and have been used for sometime for estimating population incidence. However, recent work demonstrated limitations of this approach which included subtype-dependent performance and significant variability of "window periods", precluding its use in many areas of the world. Recently an IgG-Capture BED-EIA was developed in our laboratory which detects the increasing HIV-IgG as proportion of total IgG following seroconversion and can be used to detect recent seroconversion. The format of the assay, which includes a multi-subtype derived antigen, allows high consistency and similar "window periods" in different subtypes. This assay is now available commercially and is made specifically for population estimates of HIV-1 incidence. Due to the presence of divergent HIV-1 subtypes and the rapidly expanding HIV epidemic, it is important that the method selected is robust, performs similarly in different subtypes and is widely applicable for meaningful incidence estimates, trend analysis and comparison between populations.

Prevalence of HBV, HCV, HIV - 1,2 and HTLV - I/II infections among blood donors in a teaching hospital in the central region of Saudi Arabia.

Several infectious diseases are transmissible by blood transfusion, especially viral infections. The most common blood-transmitted viruses are hepatitis B virus [HBV], hepatitis C virus [HCV] and human immunodeficiency virus [HIV]. These viruses cause fatal, chronic and life-threatening disorders. The prevalence of these viruses varies by nationality and geography. The purpose of this study was to establish the current prevalence of hepatitis viruses [B and C] and human retroviruses [HIV-1, 2 and human T-lymphotropic virus type I and II, HTLV-I /II] among blood donors at King Khalid University Hospital [KKUH], Riyadh, Kingdom of Saudi Arabia [KSA]. Serological markers of HBV, HCV, HIV 1, 2 and HTLV-I/II were studied in 24173 [23952 males and 221 females], 20423 Saudi and 3750 non-Saudi blood donors, using commercially available kits, over a period of 3 years from January 2000 to December 2002 at KKUH, Riyadh, KSA. The prevalence of confirmed-positive test results of these viruses was evaluated among different gender, ages and nationalities. During the study period, prevalence rates of HBV and HCV infections were 1.5% and 0.4%, and zero for retroviral infections. The prevalence was not significantly higher in male than in female donors. Hepatitis B surface antigen [HBsAg] and anti-HCV positivity tend to increase with increase in age. The prevalence of HBsAg and anti-HCV positivity was significantly more prevalent among non-Saudi compared to Saudi donors. This study highlights the prevalence rates of HBV and HCV among different groups. The prevalence varies from one group to another, being the lowest among Saudi and young donors. Therefore, extensive recruitment of Saudi and young donors should help ensure a long-term increase in the blood supply without jeopardizing safety

Anti-HIV-1 antibody testing using modified gelatin particle agglutination: a large field study.

Anti-HIV testing using gelatin particle agglutination (GPA) assay was investigated in parallel with ELISAs from routine service at Siriraj Hospital. In the first strategy, 174,032 sera from a patient population with an HIV-1 seroprevalence of 13.72 per cent were assayed using reduced volumes of GPA reagents, giving a cost reduction of 40 per cent. In the second strategy, 90,560 pregnant women and 48,936 emigrant workers with an HIV-1 seroprevalence of 2.2 per cent and 0.3 per cent, respectively, were tested in pools of 4 sera using the manufacturer's recommended volumes, giving a cost saving of 67 per cent. Overall, the sensitivity and specificity were almost identical with standard methods. Thus, parallel use of either modified GPA might be considered appropriate when testing large numbers of samples. However, both modified versions of GPA are not recommended as the first assay for diagnostic or blood bank screening especially in high prevalence of HIV infection.