Detection of antibodies to human immunodeficiency virus type 1 in oral fluids: a large-scale evaluation of immunoassay performance

A Review on Saliva-Based Health Diagnostics: Biomarker Selection and Future Directions

The human body has a unique way of saying when something is wrong with it. The molecules in the body fluids can be helpful in the early detection of diseases by enabling health and preventing disease progression. These biomarkers enabling better healthcare are becoming an extensive area of research interest. Biosensors that detect these biomarkers are becoming the future, especially Point Of Care (POC) biosensors that remove the need to be physically present in the hospital. Detection of complex and systemic diseases using biosensors has a long way to go. Saliva-based biosensors are gaining attention among body fluids due to their non-invasive collection and ability to detect periodontal disease and identify systemic diseases. The possibility of saliva-based diagnostic biosensors has gained much publicity, with companies sending home kits for ancestry prediction. Saliva-based testing for covid 19 has revealed effective clinical use and relevance of the economic collection. Based on universal biomarkers, the detection of systemic diseases is a booming research arena. Lots of research on saliva-based biosensors is available, but it still poses challenges and limitations as POC devices. This review paper talks about the relevance of saliva and its usefulness as a biosensor. Also, it has recommendations that need to be considered to enable it as a possible diagnostic tool.

Graphical Abstract

Urine and Saliva: Relevant Specimens for Malaria Diagnosis?

Blood remains the specimen of preference for malaria diagnosis, whether it is for microscopic, nucleic acid-based or biomarker detection of Plasmodium present in a patient. However, concerning the disadvantages of blood drawing, specimens that can be non-invasively collected under non-hygienic settings would come in handy for malaria diagnosis in endemic areas with limited resources. Although the current approaches using saliva or urine might not be as sensitive and specific as using blood, the potential of these two specimens should not be underestimated and efforts in developing diagnostic methods for Plasmodium detection specifically in these two specimens should continue without giving up. This review not only compiles and summarizes the sensitivity and specificity achieved by various detection approaches when using these samples for malaria diagnosis, it also intends to enhance the possibility of using saliva and urine for diagnostic purposes by describing how Plasmodium nucleic acid and antigens may likely be present in these samples. This review may hopefully encourage and motivate researchers in developing saliva- and urine-based diagnostic methods for Plasmodium detection to facilitate the control and eradication of malaria. In summary, the presence of Plasmodium DNA and antigens in urine and saliva makes these two specimens relevant and useful for malaria diagnosis.

Sensitive Serology Measurements in the Saliva of Individuals with COVID-19 Symptoms Using a Multiplexed Immunoassay

BACKGROUND

There are numerous benefits to performing salivary serology measurements for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen for coronavirus disease 2019 (COVID-19). Here, we used a sensitive multiplex serology assay to quantitate salivary IgG against 4 SARS-CoV-2 antigens: nucleocapsid, receptor-binding domain, spike, and N-terminal domain.

METHODS

We used single samples from 90 individuals with COVID-19 diagnosis collected at 0 to 42 days postsymptom onset (PSO) and from 15 uninfected control subjects. The infected individuals were segmented in 4 groups (0-7 days, 8-14 days, 15-21 days, and >21 days) based on days PSO, and values were compared to controls.

RESULTS

Compared to controls, infected individuals showed higher levels of antibodies against all antigens starting from 8 days PSO. When applying cut-offs with at least 93.3% specificity at every time interval segment, nucleocapsid protein serology had the best sensitivity at 0 to 7 days PSO (60% sensitivity [35.75% to 80.18%], ROC area under the curve [AUC] = 0.73, P = 0.034). Receptor-binding domain serology had the best sensitivity at 8 to 14 days PSO (83.33% sensitivity [66.44%-92.66%], ROC AUC = 0.90, P < 0.0001), and all assays except for N-terminal domain had 92% sensitivity (75.03%-98.58%) at >14 days PSO.

CONCLUSIONS

This study shows that our multiplexed immunoassay can distinguish infected from uninfected individuals and reliably (93.3% specificity) detect seroconversion (in 60% of infected individuals) as early as the first week PSO, using easy-to-collect saliva samples.

Self-collection of capillary blood and saliva to determine COVID-19 vaccine immunogenicity in patients with immune-mediated inflammatory diseases and health professionals

Introduction

Being able to independently determine vaccine induced antibody responses by minimal-invasive methods is of great interest to enable a flexible and effective vaccination strategy. This study aimed to evaluate (1) the accuracy, feasibility, usability and acceptability of capillary blood and saliva self-sampling to determine SARS-CoV-2 antibody responses in patients with immune-mediated inflammatory diseases (IMIDs) and health professionals (HP).

Methods

IMID patients and HP having received two doses of SARS-CoV-2 vaccines, self-collected capillary blood (Tasso+) and saliva samples. Capillary samples were considered interchangeable with venous blood if three criteria were met: Spearman's correlation coefficient (r) > 0.8, non-significant Wilcoxon signed-rank test (i.e., p > 0.05), and a small bias or 95% of tests within 10% difference through Bland-Altman. Participants completed a survey to investigate self-sampling usability (system usability scale; SUS) and acceptability (net promoter score; NPS). Study personnel monitored correct self-sampling completion and recorded protocol deviations.

Results

60 participants (30 IMID patients and 30 HP) were analyzed. We observed interchangeability for capillary samples with an accuracy of 98.3/100% for Anti-SARS-CoV-2 IgG/IgA antibodies, respectively. Fifty-eight capillary blood samples and all 60 saliva samples were successfully collected within the first attempt. Usability of both self-sampling procedures was rated as excellent, with significantly higher saliva ratings (p < 0.001). Capillary self-sampling was perceived as significantly (p < 0.001) less painful compared to traditional venous blood collection. Participants reported a NPS for capillary and saliva self-sampling of +68% and +63%, respectively. The majority of both groups (73%) preferred capillary self-sampling over professional venous blood collection.

Conclusion

Our results indicate that capillary self-sampling is accurate, feasible and preferred over conventional venous blood collection. Implementation could enable easy access, flexible vaccination monitoring, potentially leading to a better protection of vulnerable patient groups. Self-collection of saliva is feasible and safe however more work is needed to determine its application in clinical practice.

Saliva-based SARS-CoV-2 serology using at-home collection kits returned via mail

Serology provides tools for epidemiologic studies, and may have a role in vaccine prioritization and selection. Automated serologic testing of saliva, especially specimens that are self-collected at home and sent to a laboratory via the mail without refrigeration, could be a highly-scalable strategy for population-wide testing. In this prospective study, non-vaccinated patients were recruited after PCR testing to self-collect saliva and return their specimens via mail. Longitudinal specimens were analyzed in order to monitor seroconversion in the weeks after a diagnostic PCR test for SARS-CoV-2. Diverse users self-collected saliva and returned specimens via mail in compliance with shipping regulations. At our pre-established threshold (0.963 AU/mL), salivary IgG reactivity to full-length spike protein achieved 95.8% sensitivity and 92.4% specificity at 2–4 weeks after diagnostic testing, which is comparable to the typical sensitivity and specificity achieved for serum testing. Reactivity to N antigen also was detected with 92.6% sensitivity and 90.7% specificity at 4–8 weeks after diagnostic testing. Moreover, serologic testing for endemic coronaviruses performed in multiplex with SARS-CoV-2 antigens has the potential to identify samples that may require retesting due to effects of pre-analytical factors. The easy-to-use saliva collection kit, coupled with thresholds for positivity and methods of flagging samples for retest, provides a framework for large-scale serosurveillance of SARS-CoV-2.

Ultrasensitive detection of salivary SARS-CoV-2 IgG antibodies in individuals with natural and COVID-19 vaccine-induced immunity

We assessed the feasibility of a highly sensitive immunoassay method based on single molecule array (Simoa) technology to detect IgG and IgA antibodies against SARS-CoV-2 spike protein receptor binding domain (RBD) in saliva from individuals with natural or vaccine-induced COVID-19 immunity. The performance of the method was compared to a laboratory-developed SARS-CoV-2 RBD total antibody enzyme-linked immunosorbent assay (ELISA). Paired serum and saliva specimens were collected from individuals (n = 40) prior to and 2 weeks after receiving an initial prime COVID-19 vaccine dose (Pfizer/BioNTech BNT162b2 or Moderna mRNA-1273). Saliva was collected using a commercially available collection device (OraSure Inc.) and SARS-CoV-2 RBD IgG antibodies were measured by an indirect ELISA using concentrated saliva samples and a Simoa immunoassay using unconcentrated saliva samples. The IgG results were compared with paired serum specimens that were analyzed for total RBD antibodies using the ELISA method. The analytical sensitivity of the saliva-based Simoa immunoassay was five orders of magnitude higher than the ELISA assay: 0.24 pg/mL compared to 15 ng/mL. The diagnostic sensitivity of the saliva ELISA method was 90% (95% CI 76.3-97.2%) compared to 91.7% (95% CI 77.5-98.2%) for the Simoa immunoassay without total IgG-normalization and 100% (95% CI 90.3-100%) for the Simoa immunoassay after total IgG-normalization when compared to the serum ELISA assay. When analyzed using the SARS-CoV-2 RBD IgG antibody ELISA, the average relative increase in antibody index (AI) between the saliva of the post- and pre-vaccinated individuals was 8.7 (AIpost/pre). An average relative increase of 431 pg/mL was observed when the unconcentrated saliva specimens were analyzed using the Simoa immunoassay (SARS-CoV-2 RBD IgGpost/pre). These findings support the suitability of concentrated saliva specimens for the measurement of SARS-CoV-2 RBD IgG antibodies via ELISA, and unconcentrated saliva specimens for the measurement of SARS-CoV-2 RBD IgG and IgA using an ultrasensitive Simoa immunoassay.

Quantitative serology for SARS-CoV-2 using self-collected saliva and finger-stick blood

Convenient and widespread serology testing may alter the trajectory of the COVID-19 pandemic. This study seeks to leverage high-throughput, multiplexed serologic assays, which have been adopted as benchmarks for vaccine efficacy, to support large-scale surveys of SARS-CoV-2 immunity using finger-stick blood and/or saliva. Specifically, we optimized MSD's serology assays, which were analytically validated for serum, to test self-collected finger-stick blood and saliva samples to identify prior infection. We show that these assays can be used with FDA-registered specimen collection devices to obtain quantitative measurements for self-collected samples. First, we show that salivary antibodies are stable without refrigeration or preservatives for at least 5 days. We selected classification thresholds for antibodies against SARS-CoV-2 N, RBD and Spike in finger-stick blood and saliva that provided 98% specificity in a set of individuals without known COVID-19 exposure. Using matched samples, we show that testing of saliva and finger-stick blood equivalently identified individuals with humoral responses to CoV-2 antigens. Moreover, we piloted a simple saliva collection kit that can be used to safely send samples through the mail using written instructions only. This work establishes key parameters to robustly assay self-collected finger-stick blood and saliva using quantitative immunoassays that could support large-scale serology testing.

Comparison of conventional and non-invasive diagnostic tools for detecting Plasmodium falciparum infection in southwestern Cameroon: a cross-sectional study

Background

Malaria remains a significant health challenge in sub-Saharan Africa, with early diagnosis critical to reducing its morbidity and mortality. Despite the increasing Plasmodium spp. diagnostic capabilities, access to testing is limited in some cases by the almost absolute requirement for blood from potentially infected subjects as the only sample source for all conventional methods. A rapid test on non-invasive specimen with comparable performance to microscopy for the screening or diagnosis of all participants is invaluable. This study sought to compare conventional and non-invasive diagnostic tools for detecting Plasmodium falciparum.

Methods

This was a cross-sectional study, carried out between March and August 2019 to evaluate and compare the diagnostic performance of a PfHRP2/pLDH-based malaria rapid diagnostic test (mRDT) on patients’ blood, saliva and urine relative to conventional light microscopy and nested PCR at outpatient clinics in the Buea and Tiko health districts of Southwestern Cameroon. The significance of differences in proportions was explored using the Pearson’s χ² test whereas differences in group means were assessed using analyses of variance.

Results

A total of 359 individuals of both sexes, aged 1–92 years, were enrolled into the study. Of the 301 individuals tested by light microscopy and mRDTs on blood, saliva and urine, 84 (27.9%), 81 (26.9%), 87 (28.9%) and 107 (35.5%) respectively were positive. However, only 34.3%, 90.5%, 91.4%, 83.9% and 65.4% febrile, light microscopy and mRDT positives on blood, saliva and urine respectively had P. falciparum infection as confirmed by PCR. The sensitivity and specificity of presumptive diagnosis, light microscopy and mRDT on blood, saliva and urine were 86.9% and 19.7%, 77.8% and 96.1%, 75.8% and 96.6%, 74.5% and 93.1%, and 70.7% and 81.8%, respectively. The agreement between mRDT on saliva (k = 0.696) and microscopy (k = 0.766) compared to PCR was good.

Conclusion

The study highlighted the low performance of presumptive diagnosis, reinforcing the need for parasitological tests prior to antimalarial therapy. The higher PfHRP2/pLDH mRDT parasite detection rates and sensitivity in saliva compared to urine suggests that the former is a practical adjunct to or alternative worth optimising for the routine diagnosis of malaria.

Graphic Abstract

Flow chart for diagnosis of P. falciparum infection by light microscopy, rapid diagnostic tests and nested PCR.

Role of Primary Health Care teams in rapid testing for Sexually Transmitted Infections

ABSTRACT This research aims at describing the professional practices of Primary Health Care teams regarding rapid tests for STDs. It follows a descriptive study under a quantitative approach; participants include 18 municipalities, 94 Basic Health Units, and 100 staff teams working on Family Health Strategies. The sample was composed of the managers and the staff members directly involved in the testing, while the variables included adhesion to the tests and factors regarding the testing process. Data collection was performed in loco through a semi-structured instrument. Rapid tests were offered by 93% of the teams, 78.5% offering the tests to any users. In 89.2% of the staff teams, the nurse was solely responsible for collecting tests; 55.9% of members did not feel confident about reporting on a positive result, while 63.1% of those who considered the community health agent the main form of outreach assessed their performance as inadequate. Treatment against syphilis accounts for 50.5%. There is fair adhesion to testing by part of the staff teams; the focus on the nurse, however, leads to an increase in their workload, highlighting their protagonism, leading to a reflection on professional practices and paving the way for different realities to be further investigated

Evaluation and diagnostic usefulness of saliva for detection of HIV antibodies: A cross-sectional study

Background:

Use of saliva as a specimen for detection of antibodies to infectious agents has generated particular interest in AIDS research community since 1980s. HIV specific antibodies of immunoglobulin isotypes IgA, IgG, and IgM are readily found in salivary secretions.

Aim and Objectives:

In the present study, HIV specific antibodies were detected in saliva and serum samples of HIV patients by ELISA in confirmed HIV seropositive patients and efficacy of saliva was established in diagnosis of HIV.

Methods:

The 100 saliva and serum samples were collected from age and sex matched confirmed HIV seropositive subjects and 100 Healthy Controls without any infections. HIV antibodies were determined by enzyme-linked immunosorbent assay (ELISA) using Genscreen HIV 1/2 Kit.

Results:

The results were found to be 99% sensitive and 100% specific for saliva samples, while it was 100% sensitive and specific for serum samples.

Conclusion:

Saliva can be used as alternative to blood for detection of HIV antibodies as saliva collection is painless, non-invasive, inexpensive, simple, and rapid. Salivary antibody testing may provide better access to epidemic outbreaks, children, large populations, hard-to-reach risk groups and may thus play a major role in the surveillance and control of highly infectious diseases.

Brief Report: Diagnostic Accuracy of Oral Mucosal Transudate Tests Compared with Blood-Based Rapid Tests for HIV Among Children Aged 18 Months to 18 Years in Kenya and Zimbabwe

Gaps persist in HIV testing for children who were not tested in prevention of mother-to-child HIV transmission programs. Oral mucosal transudate (OMT) rapid HIV tests have been shown to be highly sensitive in adults, but their performance has not been established in children.

Use of the Bio-Rad Geenius HIV-1/2 supplemental assay for the testing of oral fluids for the presence of HIV antibody

There is currently an absence of products which are cleared by the FDA to provide supplemental testing for oral fluid for HIV antibody. We created a procedure for the use of the BioRad Geenius HIV-1/2 as a supplemental antibody test for oral fluid specimens. The modified procedure was evaluated for its ability to detect HIV-1 antibody in oral fluid in specimens that were found to be repeatedly reactive for HIV-1 antibody by way of the Avioq HIV-1 enzyme immunoassay (EIA). Evaluated were oral fluid specimens analyzed at a local public health laboratory which were stored frozen and oral fluid specimens collected prospectively. Prospectively collected specimens were from patients whose HIV status was subsequently assessed through blood-based testing. For retrospective specimens found repeatedly EIA reactive, and positive by Western blot, the modified Geenius was found positive in 37/38 instances (97.4 %). Those specimens with a mean EIA signal-to-cutoff (S/CO) greater than 3.00 were found to be positive by Geenius in 34/34 (100 %) of instances. For specimens found repeated reactive by EIA and positive by Western blot with mean S/CO less than or equal to 3.00, the Geenius was positive in 4/5 instances (80 %) of instances. For prospectively collected specimens, the Geenius accurately confirmed infection in 22/24 cases (92 %) while prospective specimens found repeatedly reactive by EIA without supplemental Geenius testing were confirmed positive in 29/37 instances (78 %). A modified usage of the Geenius HIV-1/2 Supplemental Assay antibody test may provide utility in the supplementation of testing of oral fluid for the presence of HIV-1 antibody.

Noninvasive Detection of Antibodies to Human T-Cell Lymphotropic Virus Types 1 and 2 by Use of Oral Fluid

Human T-lymphotropic viruses type 1 and 2 (HTLV-1/2) are prevalent in endemic clusters globally, and HTLV-1 infects at least 5 to 10 million individuals. Infection can lead to inflammation in the spinal cord, resulting in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or adult T cell leukemia/lymphoma (ATL). Obtaining venous blood for serological screening, typically performed using enzyme immunoassays (EIAs), is invasive, sometimes socially unacceptable, and has restricted large-scale seroprevalence studies. Collecting oral fluid (OF) is a noninvasive alternative to venesection. In this study, an IgG antibody capture EIA was developed and validated to detect anti-HTLV-1/2 IgG in OF. OF and plasma specimens were obtained from seropositive HTLV-1/2-infected patients attending the National Centre for Human Retrovirology (n = 131) and from HTLV-1/2-uninfected individuals (n = 64). The assay showed good reproducibility and high diagnostic sensitivity (100%) and specificity (100%) using both OF and plasma. The Murex HTLV I+II commercial assay was evaluated and did not detect anti-HTLV-1/2 IgG in 14% (5/36) of OF specimens from seropositive donors. The reactivities of OF and plasma in the IgG capture correlated strongly (r = 0.9290) and were not significantly affected by delayed extraction when held between 3°C and 45°C for up to 7 days to simulate field testing. The use of OF serological screening for HTLV-1/2 infection could facilitate large-scale seroprevalence studies, enabling active surveillance of infection on a population level.

Analysis of False-Negative Human Immunodeficiency Virus Rapid Tests Performed on Oral Fluid in 3 International Clinical Research Studies

Background.

The OraQuick Advance Rapid HIV-1/2 Test is a point-of-care test capable of detecting human immunodeficiency virus (HIV)-specific antibodies in blood and oral fluid. To understand test performance and factors contributing to false-negative results in longitudinal studies, we examined results of participants enrolled in the Botswana TDF/FTC Oral HIV Prophylaxis Trial, the Bangkok Tenofovir Study, and the Bangkok MSM Cohort Study, 3 separate clinical studies of high-risk, HIV-negative persons conducted in Botswana and Thailand.

Methods.

In a retrospective observational analysis, we compared oral fluid OraQuick (OFOQ) results among participants becoming HIV infected to results obtained retrospectively using enzyme immunoassay and nucleic acid amplification tests on stored specimens. We categorized negative OFOQ results as true-negative or false-negative relative to nucleic acid amplification test and/or enzyme immunoassay, and determined the delay in OFOQ conversion relative to the estimated time of infection. We used log-binomial regression and generalized estimating equations to examine the association between false-negative results and participant, clinical, and testing-site factors.

Results.

Two-hundred thirty-three false-negative OFOQ results occurred in 80 of 287 seroconverting individuals. Estimated OFOQ conversion delay ranged from 14.5 to 547.5 (median, 98.5) days. Delayed OFOQ conversion was associated with clinical site and test operator (P < .05), preexposure prophylaxis (P = .01), low plasma viral load (P < .02), and time to kit expiration (P < .01). Participant age, sex, and HIV subtype were not associated with false-negative results. Long OFOQ conversion delay time was associated with antiretroviral exposure and low plasma viral load.

Conclusions.

Failure of OFOQ to detect HIV-1 infection was frequent and multifactorial in origin. In longitudinal trials, negative oral fluid results should be confirmed via testing of blood samples.

Current diagnostic methods for HIV

Detection of HIV infection is essential for diagnosis and monitoring of the infection. There are different types of diagnostic tools available that are based on detection of HIV-specific antibodies, viral antigen or nucleic acid. Sensitivities and specificities of assays utilized for HIV detection have improved. Newer HIV testing technologies such as third-generation enzyme immunoassay which detect HIV-specific IgG and IgM antibodies, fourth-generation enzyme immunoassay which detect both anti-HIV antibodies and HIV p24 antigen and nucleic acid based tests for HIV RNA have significantly decreased the window period. This review provides an overview of current technologies for the detection and monitoring of HIV infection and recent advances in the field of HIV diagnosis.

Comparison of HIV oral fluid and plasma antibody results during early infection in a longitudinal Nigerian cohort

BACKGROUND

Oral fluid (OF) testing is a less-invasive alternative to blood-based testing for HIV. The performance of HIV OF tests has not been extensively evaluated in serially collected paired specimens from seroconverters.

OBJECTIVE

To compare paired OF and plasma test performance in a cohort of HIV-1 seroconverters from Nigeria.

STUDY DESIGN

Paired plasma and OF specimens from 14 seroconverters collected during 24 months of longitudinal follow up were included in the study. Plasma and OF were tested using Avioq HIV-1 Microelisa System, and first reactivity in plasma and OF specimens was compared. OF specimens reactive by Avioq were subsequently tested by OraSure HIV-1 Western blot. Genetic Systems HIV-1 Western blot was also performed on the corresponding plasma of the first 2 Avioq-OF positive time-points.

RESULTS

Of the 14 seroconverters, 5 (35.7%) had concordant results between plasma and OF for all time points tested, whereas 9 (64.3%) showed reactivity on plasma before OF specimens early in infection. The median delay between plasma and OF reactivity was 29 days (range: 0 day-20 months) (p<0.0039); the median overall delay for OF compared to RNA testing was 69.5 days. Delayed antibody response with OF was observed in both males and females regardless of viral load or HIV subtypes.

CONCLUSIONS

Results demonstrate decreased sensitivity of OF testing compared to blood-based testing with specimens obtained early after HIV infection. Programs that utilize OF testing in populations with increased risk of incident HIV infection should understand these limitations of OF testing.

Evaluation of performance and acceptability of two rapid oral fluid tests for HIV detection in Mozambique

Simplified HIV testing based on oral fluid (OF) may allow the expansion of HIV infection counseling and testing (CT) while reducing the risk due to exposure to needles and blood collection. This study evaluated the performance and acceptability of two OF tests (the OraQuick Advance Rapid HIV-1/2 and the Chembio DPP HIV-1/2) from May to September 2009 in two CT sites in Maputo City, Mozambique, compared with results for the national testing algorithm. OF testing was conducted in parallel with whole blood-based testing according to the national HIV algorithm. Blood samples were collected as dried blood spot (DBS) specimens from all participants for quality assurance. HIV infection results were delivered according to the national algorithm. According to the national HIV algorithm, 512 (30.5%) samples were reactive, 1,151 (68.7%) were nonreactive, and 13 (0.8%) were discordant. All discordant cases were retested with an enzyme immunoassay followed by Western blotting, and five (38.5%) were confirmed as HIV positive. The OraQuick OF test showed 518 (30.9%) reactive samples and 1,158 (69.1%) nonreactive samples, with a sensitivity and specificity of 99.8% and 99.8%, respectively. The Chembio DPP OF test showed 519 (31.0%) reactive samples and 1,157 (69.0%) nonreactive samples with a sensitivity and specificity of 100% and 99.8%, respectively. The participants perceived blood testing (49.9%) to be more accurate than OF testing (46.8%). The OF tests showed high performance for the diagnosis of HIV infection when examined individually and in an algorithm, compared with results according to the national testing algorithm.

Detection of human immunodeficiency virus using oral mucosal transudate by rapid test

CONTEXT

On the cusp of the fourth decade of the acquired immunodeficiency syndrome epidemic, the world has turned the corner - it has halted and began to reverse the spread of human immunodeficiency virus (HIV). Oral fluid-based Rapid tests have potential advantages over blood-based tests hence the time is ripe for their use to scale up HIV screening and testing programmes.

AIMS AND OBJECTIVES

To detect HIV using oral mucosal transudate (OMT) and to assess the sensitivity and specificity of the HIV Rapid test using OMT.

SETTINGS AND DESIGN

OraQuick Rapid HIV-1/2 Diagnostic test was evaluated in sera and oral fluids from 83 subjects.

MATERIALS AND METHODS

The study group comprised of 50 HIV seropositive subjects and the control group comprised of 33 seronegative subjects. Serum samples were collected using the standard phlebotomy technique and oral samples were collected using OraQuick Rapid HIV 1/2 Antibody test OMT collecting device.

STATISTICAL ANALYSIS USED

The statistical analysis was done using statistical package for social sciences version 16.0, SPSS Inc., 233 South Wacker Drive, 11(th) Floor, Chicago, IL 60606-6412. The Sensitivity, specificity, positive predictive value, negative predictive value were used.

RESULTS

All the subjects who tested either positive/reactive or negative/non-reactive with Western blot/enzyme-linked immunosorbent assay (ELISA) produced similar results with Rapid test using OMT in study, our study also revealed that the subjects whether on anti-retroviral therapy or not had 100% sensitivity and specificity with the Rapid test using OMT.

CONCLUSIONS

The Rapid test using OMT is highly accurate as the diagnostic efficacy in our study was 100% for HIV antibody detection and produced similar results to that of conventional Western blot/ELISA tests.

Detecting viruses by using salivary diagnostics

BACKGROUND

Diagnostics that involve the use of oral fluids have become increasingly available commercially in recent years and are of particular interest because of their relative ease of use, low cost and noninvasive collection of oral fluid for testing.

TYPES OF STUDIES REVIEWED

The authors discuss the use of salivary diagnostics for virus detection with an emphasis on rapid detection of infection by using point-of-care devices. In particular, they review salivary diagnostics for human immunodeficiency virus, hepatitis C virus and human papillomavirus. Oral mucosal transudate contains secretory immunoglobulin (Ig) A, as well as IgM and IgG, which makes it a good source for immunodiagnostic-based devices.

CLINICAL IMPLICATIONS

Because patients often visit a dentist more regularly than they do a physician, there is increased discussion in the dental community regarding the need for practitioners to be aware of salivary diagnostics and to be willing and able to administer these tests to their patients.

HIV diagnosis and testing: what every healthcare professional can do (and why they should)

Over the last thirty years, the human immunodeficiency virus (HIV) epidemic has matured. In the United States, HIV has changed from an explosive outbreak to an endemic disease; currently, an estimated 1.1 million people are infected with HIV, including a substantial number who are unaware of their status. With recent findings demonstrating the high transmissibility of HIV early in infection, and the potential benefit of early initiation of treatment, it is essential to identify as many infected individuals as possible. The Centers for Disease Control and Prevention (CDC) has expanded HIV testing to include any healthcare setting, including dental offices. Testing advances, including oral testing, have reduced the window period of HIV infection. Dental care represents a key, reliable, independent, and confidential link between the healthcare system and the general population that has been under-utilized in the effort to control the HIV epidemic. HIV testing is straightforward, and knowledge of the types of testing will afford dentists an important opportunity to help advance and preserve the health of their patients and to promote the public health of their community. Here, we review the basics of HIV testing and discuss new changes in the approach to HIV diagnostics.

Detection of human immunodeficiency virus using oral mucosal transudate by rapid test

CONTEXT

On the cusp of the fourth decade of the acquired immunodeficiency syndrome epidemic, the world has turned the corner - it has halted and began to reverse the spread of human immunodeficiency virus (HIV). Oral fluid-based Rapid tests have potential advantages over blood-based tests hence the time is ripe for their use to scale up HIV screening and testing programmes.

AIMS AND OBJECTIVES

To detect HIV using oral mucosal transudate (OMT) and to assess the sensitivity and specificity of the HIV Rapid test using OMT.

SETTINGS AND DESIGN

OraQuick Rapid HIV-1/2 Diagnostic test was evaluated in sera and oral fluids from 83 subjects.

MATERIALS AND METHODS

The study group comprised of 50 HIV seropositive subjects and the control group comprised of 33 seronegative subjects. Serum samples were collected using the standard phlebotomy technique and oral samples were collected using OraQuick Rapid HIV 1/2 Antibody test OMT collecting device.

STATISTICAL ANALYSIS USED

The statistical analysis was done using statistical package for social sciences version 16.0, SPSS Inc., 233 South Wacker Drive, 11(th) Floor, Chicago, IL 60606-6412. The Sensitivity, specificity, positive predictive value, negative predictive value were used.

RESULTS

All the subjects who tested either positive/reactive or negative/non-reactive with Western blot/enzyme-linked immunosorbent assay (ELISA) produced similar results with Rapid test using OMT in study, our study also revealed that the subjects whether on anti-retroviral therapy or not had 100% sensitivity and specificity with the Rapid test using OMT.

CONCLUSIONS

The Rapid test using OMT is highly accurate as the diagnostic efficacy in our study was 100% for HIV antibody detection and produced similar results to that of conventional Western blot/ELISA tests.

HIV prevalence and risk among heterosexual methamphetamine injectors in California

This study funded by Centers for Disease Control compares HIV prevalence and risk behavior among heterosexual methamphetamine (n = 428) and nonmethamphetamine (n = 878) injectors in California, USA, during 2001-2003. While HIV was not highly prevalent among methamphetamine injectors (3%), sexual and injection risk behaviors were highly prevalent (ranging from 21% to 72%). In multivariate analyses, methamphetamine injectors had higher odds than nonmethamphetamine injectors of unprotected vaginal intercourse and sex with five or more sexual partners in the past 6 months and of distributive and receptive syringe sharing in the past 30 days. There was no significant difference in HIV sero-status by methamphetamine use. Suggestions are made for designing HIV prevention programs. The study's limitations are noted.

Detection of HIV-1 in Saliva: Implications for Case-Identification, Clinical Monitoring and Surveillance for Drug Resistance

Background:

Saliva tests that detect antibodies are used to diagnose HIV infection. The goal of this study was to determine whether saliva could be used for nucleic acid-based tests to measure HIV-1 virus load (VL) and detect drug resistance.

Methods:

69 HIV infected individuals provided 5-10 ml of saliva and blood samples. Viral RNA was isolated from saliva and dried blood spots using the Nuclisens extraction. Saliva VL was measured using a modified Amplicor assay, and genotyping was performed using an in-house RT-PCR/sequencing protocol. Plasma VLs were obtained from concurrently drawn clinical tests.

Results:

Thirty-six of 47 (77%) plasma viremic patients had measurable saliva HIV-1 RNA. Paired plasma and saliva HIV RNA levels were significantly correlated (Spearman’s correlation = .6532, p<.0001), but saliva VL was typically lower. Three of 22 patients with undetectable plasma VL (<50 copies/ml) had detectable saliva HIV RNA. Eleven of 30 patients with undetectable saliva RNA had detectable plasma HIV-1 RNA. Comparison of the protease and reverse transcriptase gene sequences from paired saliva and plasma of 20 patients showed less than 1% difference overall, and few resistance-related amino acid differences

Conclusions:

Most patients with plasma virus >50 copies/mL had detectable saliva HIV RNA, and the genotypic data was highly concordant between saliva and plasma. In patients with high levels of plasma HIV RNA, saliva might be useful in identifying viremia and evaluating drug resistance.

Feasibility of a Population Based Survey on HIV Prevalence in Barbados, and Population Preference for Sample Identification Method

OBJECTIVE

To predict response rate and validity of a population-based HIV prevalence survey in Barbados using oral fluid, and the method of sample identification preferred by participants.

METHODS

Persons age 18 to 35 randomly selected from the voters' register to participate in a study of the prevalence of chlamydia and gonorrhoea (STI) were invited to answer a questionnaire.

RESULTS

Of 496 persons selected for the STI study, 88 did not participate, and a further 10 did not answer the questionnaire, leaving 398 respondents. 329 persons or 66% (60% men, 73% women, p = 0.003) of the original 496 persons said that they would be willing to take part in an HIV survey using oral fluid. People indicating willingness to take part in an HIV survey did not differ significantly from non-respondents and those indicating unwillingness to participate by a number of demographic and STI risk factors including age, education level, partnership status, number of partners, condom use, drug use, and STI infection status. For persons willing to participate in a HIV survey, confidential linked sample identification was acceptable to 99.0% (95% CI +/- 1.0), and unlinked identification to 1.6% (95% CI +/- 1.3).

CONCLUSION

The HIV prevalence estimated by a linked survey would have a reasonable response rate and be valid, as likelihood of participation is not related to infection risk.

Oral fluid tests for screening of human immunodeficiency virus-exposed infants

In high human immunodeficiency virus (HIV) prevalence settings, routine screening of infants attending immunization visits could improve identification of HIV-exposed infants to receive an early diagnosis and appropriate interventions. This first assessment of 2 rapid oral fluid HIV tests in early infancy demonstrates a sensitivity of <90% for detection of HIV-exposure resulting in failure to detect at least 1 in 10 HIV-infected infants.

Assessment of sensitivity and specificity of first, second, and third generation EIA for the detection of antibodies to HIV-1 in oral fluid

The performances of three blood-based immunoassays test kits were compared with regard to their ability to detect HIV-1 antibody in oral fluid. It was found that these three kits differ in their ability to detect HIV-1 antibody. Notably, a third generation EIA which has been shown to possess superior sensitivity for antibody detection in plasma appears to possess no sensitivity advantage for detecting HIV-1 antibody in oral fluid.

Micro- and nanotechnology for viral detection

Since the identification of viruses at the start of the 20th century, detecting their presence has presented great challenges. In the past two decades, there has been significant progress in viral detection methods for clinical diagnosis and environmental monitoring. The earliest advances were in molecular biology and imaging techniques. Advances in microfabrication and nanotechnology have now begun to play an important role in viral detection, and improving the detection limit, operational simplicity, and cost-effectiveness of viral diagnostics. Here we provide an overview of recent advances, focusing especially on advances in simple, device-based approaches for viral detection.

Changes in HIV prevalence and risk among new injecting drug users in a Russian city of high HIV prevalence

OBJECTIVE

To measure HIV prevalence and associated risk factors among recent initiates into drug injecting in 2001 and 2004 in Togliatti City, Russian Federation.

DESIGN

Two unlinked, anonymous, cross-sectional, community-recruited surveys of injecting drug users (IDUs) with oral fluid samples for anti-HIV testing.

METHODS

IDUs completed an interviewer-administered questionnaire, and oral fluid samples were tested for antibodies to HIV. Demographic characteristics and injecting risk behaviors were compared between subsamples of IDUs who reported injecting for 3 years or less in each of the survey years, 2001 (n = 138) and 2004 (n = 96). Univariable and multivariable analyses explored risk factors with anti-HIV among these new injectors.

RESULTS

Among IDUs overall, although HIV prevalence was high, a lower prevalence was found in 2004 (38.5%, 95% confidence interval [CI]: 34.1 to 42.9) than in 2001 (56%, 95% CI: 51.2 to 60.8). A significantly lower prevalence of HIV was found among new injectors in 2004 (11.5%, 95% CI: 5.0 to 17.9) than in 2001 (55.2%, 95% CI: 46.7 to 63.8). Proportionally, fewer new injectors reported injecting daily, injecting with used needles/syringes, and frontloading in 2004 compared with 2001. Decreased odds of anti-HIV were associated with being recruited in 2004 and with a history of drug treatment. Increased odds of HIV were associated with exchanging sex, duration of injection, and frontloading.

CONCLUSIONS

Findings indicate a decrease in HIV prevalence among new injectors between 2001 and 2004 and emphasize the role of provision of needle/syringes through pharmacies and providing access to voluntary HIV testing. These findings have implications for other cities in which explosive HIV outbreaks have occurred.

Detection of Plasmodium falciparum histidine-rich protein II in saliva of malaria patients

Detection of Plasmodium falciparum parasites in patients with malaria necessitates drawing blood, which increases the risk of accidental infections and is poorly accepted in communities with blood taboos. Thus, non-invasive, cost-effective malaria tests that minimize the need for blood collection are needed. Plasmodium falciparum histidine-rich protein II (PfHRP II) levels in plasma and saliva were compared in malaria-positive and -negative patients in Ghana. Plasma and saliva obtained from 30 thick-film positive and 10 negative children were evaluated for PfHRP II by ELISA. Among the 30 children with positive blood smear, 16 (53%) were PfHRP II positive in plasma and 13 (43%) had PfHRP II positive saliva. The sensitivity of PfHRP II detection was 53% for plasma and 43% for saliva. The specificity was 100% with no false positive for both plasma and saliva when compared with blood smear. Thus, rapid detection of PfHRP II antigen in saliva may be a useful non-invasive and cost-effective malaria diagnostic technique.

Prevalence of human immunodeficiency virus, Chlamydia trachomatis, and Neisseria gonorrhoeae and risk factors for sexually transmitted infections among immigrant female sex workers in Catalonia, Spain

OBJECTIVES

To determine the prevalence of human immunodeficiency virus (HIV), Chlamydia trachomatis (CT), and Neisseria gonorrhoeae (NG) among immigrant female sex workers (FSW) according to their geographic area of origin and identify possible risk factors independently associated with current infection with CT and/or NG.

STUDY DESIGN

Cross-sectional study of 357 FSW in Catalonia in 2005. Information on sociodemographic and sex work characteristics, use of alcohol and drugs, sexual practices, and the use of social and health care services was collected. Oral fluid and urine samples were collected to determine the prevalence of HIV and CT/NG, respectively. Factors independently associated with CT/NG were assessed using multivariate logistic regression models.

RESULTS

A total of 36.4% of women were from Eastern Europe, 34.5% from Latin America, and 29.1% from Africa. Overall CT and NG prevalence were 5.9% [95% confidence interval (CI): 3.7-8.9] and 0.6% (95% CI: 0.1-2.0), respectively. No differences were observed by geographic origin. Three African women were HIV positive (overall HIV prevalence was 0.8%, 95% CI: 0.2-2.4). In multivariate analysis, younger age and unprotected sex with clients were associated with the presence of CT/NG.

CONCLUSIONS

The prevalence of sexually transmitted infections among FSW in Catalonia was lower than in other European countries. Even though the prevalence of HIV was only 0.8%, it could increase in the future given the high vulnerability of these women and their wide geographic mobility. It is necessary to continue with the work carried out by nongovernmental organizations (harm reduction programs, outreach programs, and safe sex workshops) as well as to facilitate the access to health centers, especially for the youngest women.

Repeat confirmatory testing for persons with discordant whole blood and oral fluid rapid HIV test results: findings from post marketing surveillance

Background

Reactive oral fluid and whole blood rapid HIV tests must be followed with a confirmatory test (Western blot (WB), immunofluorescent assay (IFA) or approved nucleic acid amplification test (NAAT)). When the confirmatory result is negative or indeterminate (i.e. discordant with rapid result), repeat confirmatory testing should be conducted using a follow-up specimen. Previous reports have not described whether repeat testing adequately resolves the HIV-infection status of persons with discordant results.

Methodology

Post-marketing surveillance was conducted in 368 testing sites affiliated with 14 state and 2 city health departments from August 11, 2004 to June 30, 2005 and one health department through December 31, 2005. For persons with discordant results, data were collected on demographics, risk behaviors, HIV test results and specimen types. Persons with repeat confirmatory results were classified as HIV-infected or uninfected. Regression models were created to assess risk factors for not having repeat testing.

Principal Findings

Of 167,371 rapid tests conducted, 2589 (1.6%) were reactive: of these, 2417 (93%) had positive WB/IFA, 172 (7%) had negative or indeterminate WB/IFA. Of 89/172 (52%) persons with a repeat confirmatory test: 17 (19%) were HIV-infected, including 3 with indeterminate WB and positive NAAT; 72 (81%) were uninfected, including 12 with repeat indeterminate WB. Factors associated with HIV-infection included having an initial indeterminate WB/IFA (vs. negative) (p<0.001) and having an initial oral fluid WB (vs. serum) (p<0.001). Persons who had male-female sex (vs. male-male sex) were at increased risk for not having a repeat test [adjusted OR 2.6, 95% CI (1.3, 4.9)].

Conclusions

Though only half of persons with discordant results had repeat confirmatory testing, of those who did, nearly one in five were HIV-infected. These findings underscore the need for rapid HIV testing programs to increase repeat confirmatory testing for persons with discordant results. Because of the lower sensitivity of oral fluid WBs, confirmatory testing following a reactive rapid test should be conducted using serum or plasma, when possible.

Pilot of non-invasive (oral fluid) testing for HIV within a clinical setting

BACKGROUND

The objectives of the present study were: to determine the sensitivity and specificity of oral fluid testing compared with the performance of standard blood-based HIV enzyme immunoassay; to assess the feasibility of oral fluid specimen collection from clients for the purposes of HIV testing within a clinical setting; and to assess the clinical and laboratory impact regarding staffing, material resources, expertise and funding of oral fluid testing.

METHODS

A parallel comparative trial of oral fluid and blood testing was conducted among a group of HIV positive clients and a group of unknown HIV serostatus clients where each client was offered both tests. An ambulatory HIV clinic recruited 175 known HIV positive clients and 179 persons were recruited through an inner city sexual health clinic while attending for routine sexual health checks. Client responses to oral fluid collection were assessed. The sensitivity and specificity of oral fluid testing were calculated.

RESULTS

Of the 176 confirmed HIV reactive blood test results, the OraSure (OraSure Technologies, Beaverton, OR, USA) assay failed to detect only one of these, demonstrating a sensitivity of 99.4%. Of the 178 blood specimens that were tested as non-reactive by the AxSYM (Abbott Laboratories, Abbott Park, IL, USA) Combo system, OraSure recorded four of the corresponding oral fluid specimens as reactive (assumed to be false-positive), giving a specificity of 97.6%. Although evaluation of patients undergoing the test showed a large proportion (88.6%) preferred the OraSure test to conventional blood testing, a large minority of these (22.6%) made such a preference conditional on the OraSure test being as reliable as current blood testing.

CONCLUSIONS

This limited clinic based trial of oral fluid testing for HIV antibodies among an outpatient population has demonstrated the potential of oral fluid as a specimen for HIV testing. However, the lower performance of the test compared with current serum-based tests may limit the usefulness of OraSure to epidemiological studies or as an alternative screening tool in outreach settings among higher risk populations.

Detecting Unsuspected HIV Infection With a Rapid Whole-Blood HIV Test in an Urban Emergency Department

OBJECTIVE

To evaluate and compare HIV screening and provider-referred diagnostic testing as strategies for detecting undiagnosed HIV infection in an urban emergency department (ED).

METHODS

From January 2003 through April 2004, study staff offered HIV screening with rapid tests to ED patients regardless of risks or symptoms. ED providers could also refer patients for diagnostic testing. Patients aged 18 to 54 years without known HIV infection were eligible.

RESULTS

Of 4849 eligible patients approached for screening, 2824 (58%) accepted and were tested; 414 (95%) of 436 provider-referred patients accepted and were tested. Thirty-five (1.2%) screened patients and 48 (11.6%) provider-referred patients were infected with HIV (P < 0.001). Of these, 18 (51%) screened patients and 24 (50%) referred patients reported no traditional risk factors; 27 (77%) screened patients and 38 (79%) referred patients entered HIV care. Of HIV-infected patients with CD4 cell counts available, 14 (45%) of 31 screened patients and 37 (82%) of 45 provider-referred patients had <200 cells/microL (P < 0.001).

CONCLUSIONS

ED screening detects HIV infection and links to care patients who may not be tested through risk- or symptom-based strategies. The diagnostic yield was higher among provider-referred patients, but screening detected patients earlier in the course of disease.

Effects of sex work on the prevalence of syphilis among injection drug users in 3 Russian cities

OBJECTIVES

We examined risk factors for syphilis infection among injection drug users in 3 Russian Federation cities, focusing particular attention on the potential roles of gender and sex work.

METHODS

We conducted a cross-sectional survey of injection drug users in Moscow, Volgograd, and Barnaul, collecting behavioral data and testing for antibodies to Treponema pallidum. Associations between presence of antibodies to T pallidum and covariates were explored.

RESULTS

Overall, the prevalence of antibodies to T pallidum was 11% (95% confidence interval=9.7%, 13.1%). Syphilis was associated with involvement in sex work and with gender in Moscow and Barnaul but not in Volgograd. Female injection drug users not involved in sex work were more likely than men to be younger and to have recently begun to inject; female injection drug users involved in sex work were more likely than those not involved in sex work to inject daily.

CONCLUSIONS

Syphilis transmission dynamics varied by region. Sex work can increase syphilis risk among injection drug users, potentially feeding the momentum of sexually transmitted HIV and syphilis among noninjectors. Targeted interventions are needed to reduce both sexual and injection risk behaviors among injection drug users.

Factores asociados a la práctica de compartir jeringuillas usadas entre usuarios de droga por vía parenteral reclutados en la calle

BACKGROUND AND OBJECTIVE

To estimate the prevalence of risk behaviors related to drug use and to identify factors associated with of accepting and passing on used syringes among intravenous drug users (IDU) recruited in Barcelona city and other surrounding areas in 2004.

SUBJECTS AND METHOD

A cross-sectional study of IDU recruited from the streets by ex-IDU interviewers. A standardized and anonymous questionnaire which explored behaviors in the previous 6 months was used. Saliva samples were collected to determine human immunodeficiency virus (HIV) prevalence. Logistic regression models were used to identify determinants of accepting and passing on used syringes.

RESULTS

Of the 300 participants, 17.7% and 13.3% accepted and passed on used syringes, respectively. 74.8% practiced front-backloading (to prepare the drug solution in a syringe and then divide it up into other syringes) and 77.9% shared other equipment. The prevalence of HIV was 57.7%. The predictors of accepting used syringes were using more than 4 drugs (odds ratio [OR] = 5.6), having a positive hepatitis C virus status (OR = 7.3), practising front/backloading (OR = 12.6) and having an IDU steady partner (OR = 2.9); and with passing on used syringes were practicing front/backloading (OR = 4.9), having an IDU steady partner (OR = 5.8), and having sexual risk behaviors with casual partners (OR = 4.0). Starting to inject drugs older than 15 years of age was a protective factor (OR = 0.2).

CONCLUSIONS

The prevalence of risk behaviors related to drug use remains high, especially indirect sharing, just as the prevalence of HIV and hepatitis C virus. Prevention programs should be targeted to IDU, especially to young IDU, polydrug users and those who have an IDU steady partner.

A combined HIV-1 protein bead array for serology assay and T-cell subset immunophenotyping with a hybrid flow cytometer: a step in the direction of a comprehensive multitasking instrument platform for infectious disease diagnosis and monitoring

BACKGROUND

A new generation of bench-top flow cytometers with digital signal processing to perform suspension array technology (SAT) based bead array assays as well as leukocyte immunophenotyping is now available. These hybrid instruments provide an opportunity for the development of a more cost effective multitasking platform to support infectious disease treatment in resource limited countries.

METHODS

We report the development and testing of two modules compatible with the hybrid flow cytometers. The first module is an eleven HIV-1 protein bead array (PBA) for the detection of circulating antibodies and the second is a cell based T-cell enumeration assay.

RESULTS

The HIV-1 PBA was tested in parallel with two enzyme immunoassays (EIAs) for the detection of plasma antibodies from 4 HIV-1 seroconversion panels and a low antibody titer panel. The PBA as well as the two EIAs performed equally for the detection of antibody positive samples from all seroconversion panels. One antibody positive sample from the low antibody titer panel was missed by the PBA together with one of the two EIAs tested. A parallel analysis of the HIV-1 PBA with Western blot (a confirmatory test for HIV infection) using plasma from nine HIV-1(+) individuals showed that the HIV-1 PBA detected more of the gp41 and gp120 antibody positive samples. Preliminary CD4 T-cell immunophenotyping results from 14 HIV(+) and 10 HIV(-) whole blood specimens with the hybrid flow cytometer platform compared well to conventional flow cytometry data.

CONCLUSION

The successful combination of bead and cell based assays on a single hybrid instrument demonstrated the potential utility of a multitasking platform. The results presented are providing groundwork for future development of more cost effective modular architecture for a flexible flow cytometry based platform.

Immunological and molecular detection of human immunodeficiency virus in saliva, and comparison with blood testing

In order to test the detection feasibility of human immunodeficiency virus (HIV) in saliva, a three-method blind screening analysis was conducted. Sixty-eight individuals were studied, comprising 34 HIV carriers and 34 noncarriers (controls) of matched gender and age. An oral examination preceded saliva and blood sampling of studied individuals. All samples were tested blind for HIV by using two immunological methods [Oraquick-compatible enzyme-linked immunosorbent assay (ELISA) and a fluorescent immunoenzymatic method (ELFA)], confirmed by western blotting, and a simple molecular method (polymerase chain reaction amplification of a relatively constant viral DNA region), confirmed by DNA hydridization. Compared with the controls, about twice as many HIV carriers had oral health problems, including periodontal disease. ELFA resulted in 33/34 positives and 34/34 negatives in saliva, while it detected 34/34 positives and 34/34 negatives in blood. ELISA performed even better, with correct assignment of all positives and negatives in both saliva and blood. The PCR method, at three annealing temperatures, surprisingly detected all positive samples, while it gave no false-positive result. In conclusion, the detection of anti-HIV in saliva may achieve accuracy of 97.1-100%, comparable with that in blood. Furthermore, this study suggests that a highly accurate molecular method of HIV detection may be feasible, although the studied carriers had rather homogeneous characteristics.

Detection of Ebola virus in oral fluid specimens during outbreaks of Ebola virus hemorrhagic fever in the Republic of Congo

BACKGROUND

Patients who have refused to provide blood samples has meant that there have been significant delays in confirming outbreaks of Ebola virus hemorrhagic fever (EVHF). During the 2 EVHF outbreaks in the Republic of Congo in 2003, we assessed the use of oral fluid specimens versus serum samples for laboratory confirmation of cases of EVHF.

METHODS

Serum and oral fluid specimens were obtained from 24 patients with suspected Ebola and 10 healthy control subjects. Specimens were analyzed for immunoglobulin G antibodies by enzyme-linked immunosorbent assay (ELISA) and for Ebola virus by antigen detection ELISA and reverse-transcriptase polymerase chain reaction (RT-PCR). Oral fluid specimens were collected with a commercially available collection device.

RESULTS

We failed to detect antibodies against Ebola in the oral fluid specimens obtained from patients whose serum samples were seropositive. All patients with positive serum RT-PCR results also had positive results for their oral fluid specimens.

CONCLUSIONS

This study demonstrates the usefulness of oral fluid samples for the investigation of Ebola outbreaks, but further development in antibodies and antigen detection in oral fluid specimens is needed before these samples are used for filovirus surveillance activities in Africa.

Prevalence of HIV, hepatitis C and syphilis among injecting drug users in Russia: a multi-city study

OBJECTIVES

To estimate the prevalence of HIV, hepatitis C virus (HCV) and syphilis in injecting drug users (IDUs) in Russia.

METHODS

Unlinked anonymous cross-sectional survey of 1473 IDUs recruited from non-treatment settings in Moscow, Volgograd and Barnaul (Siberia), with oral fluid sample collection for HIV, HCV antibody (anti-HIV, anti-HCV) and syphilis testing.

RESULTS

Prevalence of antibody to HIV was 14% in Moscow, 3% in Volgograd and 9% in Barnaul. HCV prevalence was 67% in Moscow, 70% in Volgograd and 54% in Barnaul. Prevalence of positive syphilis serology was 8% in Moscow, 20% in Volgograd and 6% in Barnaul. Half of those HIV positive and a third of those HCV positive were unaware of their positive status. Common risk factors associated with HIV and HCV infection across the cities included both direct and indirect sharing of injecting equipment and injection of home-produced drugs. Among environmental risk factors, we found increased odds of anti-HIV associated with being in prison in Moscow, and some association between official registration as a drug user and anti-HIV and anti-HCV. No associations were found between sexual risk behaviours and anti-HIV in any city.

CONCLUSIONS

HIV prevalence among IDUs was markedly higher than city routine surveillance data suggests and at potentially critical levels in terms of HIV prevention in two cities. HCV prevalence was high in all cities. Syphilis prevalence highlights the potential for sexual risk and sexual HIV transmission. Despite large-scale testing programmes, knowledge of positive status was poor. The scaling-up of harm reduction for IDUs in Russia, including sexual risk reduction, is an urgent priority.

Evaluation of commercial assay detecting specific immunoglobulin g in oral fluid for determining measles immunity in vaccinees

A commercial assay for detection of measles immunoglobulin G (IgG) in oral fluid was evaluated in a highly vaccinated cohort using serum IgG as gold standard. In contrast to previous studies from cohorts protected by natural immunity, antibody prevalence was significantly underestimated (-7.4%; confidence interval: -1.5 to -13.2%; P = 0.01) due to a reduced sensitivity when antibody levels were low.

Oral fluid human immunodeficiency virus tests: improved access to diagnosis for infants in poorly resourced prevention of mother to child transmission programs

BACKGROUND

Perinatal exposure of infants in low resource settings generates the bulk of pediatric human immunodeficiency virus (HIV) disease globally. The HIV status of these infants is established by testing serum for anti-HIV antibodies at 12 months of age in Prevention of Mother to Child Transmission (PMTCT) programs because polymerase chain reaction testing is unavailable. The diagnostic accuracy of 2 oral fluid (OF) HIV tests has not been previously evaluated in children.

METHODS

A serum and 2 OF HIV tests were performed at 12 months of age in a cohort of 321 vertically exposed children in a prospective, longitudinal study at a secondary level hospital in Johannesburg, South Africa during a 14-month period preceding October 2003. The 3 HIV tests were performed independently of each other by personnel blinded to the child's true HIV infection status, the reference standard used for comparison.

RESULTS

HIV testing was performed at a median age of 12.1 months. The true HIV infection status of 310 of 321 (97%) children was determined. In comparison with serum testing results, OF HIV tests reduced the percentage of children requiring repeat HIV tests from 45% to 8-12%. The abilities of OF and serum to predict an HIV-uninfected status were comparable with negative predictive values >99%. Interpretation of HIV tests in conjunction with simple clinical assessment further improved the predictive value of the test.

CONCLUSIONS

OF HIV tests perform well in children and have the potential to increase accessibility and acceptability of HIV diagnosis for infants in the context of PMTCT programs in low resource settings.

Evidence of autoantibodies to glutamic acid decarboxylase in oral fluid of type 1 diabetic patients

Circulating antibodies to glutamic acid decarboxylase (GADab) are a major indicator for autoimmune destruction of pancreatic islet cells (type 1 diabetes). Previously reported detection of GADab in oral fluid, however, was assayed by enzyme-linked immunosorbent assay (ELISA) with low diagnostic sensitivity and high non-specific binding. We re-assessed oral fluid GADab detection using a different sampling technique and a more robust assay. Type 1 diabetic subjects (n = 32; mean age +/- SD: 13.9 +/- 3.7 years) provided Orasure oral fluid and venous blood samples. Orasure collections were assayed for total immunoglobulin G (IgG), then concentrated to 1/10 of their volume using mini-centrifugal protein concentrators. All samples were assayed by a GAD65 antibody radio-immunoprecipitation method. Oral fluid antibodies were detected ( > 99th percentile of radio-binding (%counts per min (%cpm)) for seronegatives) in 10/16 seropositive subjects, with %cpm (median: 6.4%; range: 4.6-25.8) significantly greater (P < 0.001) than for seronegatives (median: 4.7%; range: 3.4-5.7). A highly significant correlation (Spearman's rho: 0.85; P<0.001) was demonstrated between %cpm of concentrates and respective serum titres for seropositive diabetics. Median IgG concentration of Orasure collections was 22.8 mg/l (range: 9.4-168.0). GADab recovery from Orasure collectors was estimated at 90%. This is the first confirmatory detection of diabetes-specific autoimmune markers in oral fluid. Acceptable correlation between concentrated oral fluid radio-binding and serum titre was achieved. Improved antibody recovery and assay re-optimisation could provide a basis for more extensive studies that may lead to an alternative non-invasive screening method for pre-clinical autoimmune diabetes.

Influence of host factors on immunoglobulin G concentration in oral fluid specimens

The influence of host factors (tobacco use, dentition, bleeding gums, oral rinsing, nasal medications, and time since the last meal) on immunoglobulin G (IgG) concentration in oral fluids (OF) was determined by univariate and multivariate analysis. Significant differences in IgG concentration were found to be associated with human immunodeficiency virus (HIV) status (HIV antibody positive, +16.60 microg/ml, P = 0.0001), sex (female, +1.23 microg/ml, P = 0.004), dentition (+2.83 microg/ml, edentulous versus dentulous, P = 0.0001), bleeding gums (+6.35 microg/ml, P = 0.0001), and time since the last meal (+3.55 microg/ml, >6 h, P = 0.0001). These factors could impact diagnostic methods that rely on the immunoglobulin concentration in OF specimens.