Accurate detection of maternal antibodies to HIV in newborn whole blood dried on filter paper

Analysis of Biological Samples Using Paper Spray Mass Spectrometry: An Investigation of Impacts by the Substrates, Solvents and Elution Methods

Paper spray has been developed as a fast sampling ionization method for direct analysis of raw biological and chemical samples using mass spectrometry (MS). Quantitation of therapeutic drugs in blood samples at high accuracy has also been achieved using paper spray MS without traditional sample preparation or chromatographic separation. The paper spray ionization is a process integrated with a fast extraction of the analyte from the raw sample by a solvent, the transport of the extracted analytes on the paper, and a spray ionization at the tip of the paper substrate with a high voltage applied. In this study, the influence on the analytical performance by the solvent-substrate systems and the selection of the elution methods was investigated. The protein hemoglobin could be observed from fresh blood samples on silanized paper or from dried blood spots on silica-coated paper. The on-paper separation of the chemicals during the paper spray was characterized through the analysis of a mixture of the methyl violet 2B and methylene blue. The mode of applying the spray solvent was found to have a significant impact on the separation. The results in this study led to a better understanding of the analyte elution, on-paper separation, as well as the ionization processes of the paper spray. This study also help to establish a guideline for optimizing the analytical performance of paper spray for direct analysis of target analytes using mass spectrometry.

Decline in the prevalence of HIV and sexually transmitted infections among female sex workers in Benin over 15 years of targeted interventions

BACKGROUND

An HIV-preventive intervention targeting the sex work milieu and involving fully integrated components of structural interventions, communication for behavioral change and care for sexually transmitted infections (STIs), was implemented in Benin by a Canadian project from 1992 to 2006. It first covered Cotonou before being extended to other main cities from 2000. At the project end, the Beninese authorities took over the intervention, but structural interventions were interrupted and other intervention components were implemented separately. We estimated time trends in HIV/STI prevalence among female sex workers (FSWs) from 1993 to 2008 and assessed the impact of the change in intervention model on trends.

METHODS

Six integrated biological and behavioral surveys were carried out among FSWs. Time trend analysis controlled for potential sociodemographic confounders using log-binomial regression.

RESULTS

In Cotonou, from 1993 to 2008, there was a significant decrease in HIV (53.3%-30.4%), gonorrhea (43.2%-6.4%), and chlamydia (9.4%-2.8%) prevalence (all adjusted P = 0.0001). The decrease in HIV and gonorrhea prevalence was also significant in the other cities between 2002 and 2008. In 2002, gonorrhea prevalence was lower in Cotonou than elsewhere (prevalence ratio = 0.53, 95% confidence interval: 0.32 to 0.88). From 2005 to 2008, there was an increase in gonorrhea prevalence (prevalence ratio = 1.76, 95% confidence interval: 1.17 to 2.65) in all cities combined.

CONCLUSIONS

Our results suggest a significant impact of this targeted preventive intervention on HIV/STI prevalence among FSWs. The recent increase in gonorrhea prevalence could be related to the lack of integration of the intervention components.

Prevalence of hepatitis C virus antibody in newborn infants in southern California in 2003

The prevalence of hepatitis C virus (HCV) antibody in newborn infants in 3 counties in southern California in 2003 was found to be 2.5 per 1000 live births using dried blood spot testing. With advances in HCV antiviral therapy providing decreasing morbidity from chronic HCV infection, prenatal HCV screening to identify both mothers and at-risk infants should be reconsidered.

Feasibility of detecting human immunodeficiency virus type 1 drug resistance in DNA extracted from whole blood or dried blood spots

Due to high cost, availability of human immunodeficiency virus type 1 (HIV-1) drug resistance testing in resource-poor settings is still limited. We therefore evaluated the usefulness of viral DNA extracted from either whole blood or dried blood spots (DBS). Samples were collected from 50 patients receiving therapy and 10 therapy-naïve patients. Amplification and sequencing of RNA and DNA was performed using an in-house assay. Protease (PR) and reverse transcriptase (RT) sequences of plasma viral RNA were obtained for 96.6% and 89.7%, respectively, of the 29 patients with a detectable viral load. For cellular viral DNA, useful PR and RT sequences were obtained for 96.6% and 93.1% of the whole-blood-cell samples and for 93.1% and 93.1% of the DBS samples, respectively. For the 31 patients with an undetectable viral load, PR and RT sequences were obtained for 67.7% and 61.3% of the whole-blood-cell DNA preparations and for 54.8% and 58.1% of the DBS DNA preparations, respectively. A good correlation between RNA and DNA sequences was found; most discordances were caused by the detection of mixed amino acids. Of the RT drug-resistant mutations, 13 (38.2%) were seen in RNA only, 6 (17.6%) in DNA only, and 15 (44.1%) in both. Repeated amplification and sequencing of DNA extracts revealed a lack of reproducibility for the detection of drug resistance mutations in a number of samples, indicating a possible founder effect. In conclusion, this study shows the feasibility of genotypic drug resistance testing on whole blood cells or DBS and its possible usefulness for HIV-1 subtyping or examining the overall distribution of drug resistance in a population. For individual patients, RNA sequencing was shown to be superior to DNA sequencing, especially for patients who experienced early treatment failure. The use of DNA extracted from whole blood or DBS for the detection of archived drug resistance mutations deserves further study.

Evaluation of the dried blood spot filter paper technology and five testing strategies of HIV-1 and HIV-2 infections in West Africa

Simple robust approaches are needed to monitor the prevalence and incidence of HIV in Africa. The aim of this study was to evaluate the use of dried blood spot (DBS) as an alternative to serum or plasma for sentinel surveillance. Paired DBS and blood samples were obtained from 200 patients attending a genito-urinary medicine clinic in West Africa. The gold standard of diagnosis was based on the combination of 3 enzyme-linked immunosorbent assays (ELISA) using serum. The presence of HIV antibodies in eluates of dried blood spots was detected by ELISA, Gelatin Particle Assay (GPA) and Pepti-Lav 1-2 in 5 different testing strategies. All 200 eluates were tested individually, and in addition pools of 5 eluates each were tested. The sensitivity of the testing strategies ranged from 95.0% (83.1 - 99.4%) to 100% and the specificity from 97.5% (93.7 - 99.3%) to 100%. Testing in pools of 5 did not affect sensitivity. Dried blood spots were easy to work with. Test kit and laboratory consumable costs varied between 492 pounds and 1037 pounds (unpooled strategies) and 163 pounds and 421 pounds (pooled). The monospecific ELISAs used in this study are no longer in production; currently available differentiating assays need to be tested. DBS are recommended for sentinel surveillance in Africa.

Whole blood samples as an alternative to serum for detection of immunity to measles virus by ELISA

The aim of this study was to evaluate enzyme linked immunosorbent assay (ELISA) as a testing strategy for detection of antibodies against measles virus from microquantities of blood soaked onto filter paper. We studied 165 healthy children in the age group of 1 to 2 years, attending the outpatient department of pediatrics. Two sets of samples were collected from each child. One by venipuncture and the other on Whatman filter paper-3 discs of 20 mm size by finger or heel prick so that each strip is completely soaked with blood on both sides. These were tested for measles virus antibodies by ELISA using Melotest measles IgG commercial ELISA kit manufactured by Melotec S. A. (Barcelona, Spain). The resulting sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the filter paper (FP) ELISA compared to serum ELISA was 100, 90, 97.8, and 100%, respectively. The correlation coefficient r = 0.93% (p < 0.001) and the agreement between the two techniques was 98% as calculated by the Kappa statistical method. The present study has found filter paper testing by ELISA to be a promising qualitative technique for detection of immunity against measles.

HIV prevalence in pregnant women in Europe: differences in assessment methods and prevalence levels across countries

OBJECTIVE

To describe methods used to assess HIV prevalence and to assess prevalence levels and time trends among pregnant women in various European countries.

METHODS

We used the European HIV Prevalence Database to examine annual HIV prevalence data in pregnant women for the years 1990 to 1996 (20 countries).

RESULTS

In Western Europe, prevalences were generally obtained through unlinked anonymous surveys, whereas in most Central, and Eastern European countries, they were based on testing programs (voluntary or mandatory). Prevalences (per 10,000) were highest (i.e., 10-30/10,000) in large western urban areas including Amsterdam, Barcelona, London, Milan, Paris, and Rome; between 1 and 2 in Scandinavian countries; and down to 0.5/10,000 in Central and Eastern European countries (except Ukraine, 1996: 5/10,000). Prevalences decreased in Rome, whereas they increased in London, the Czech Republic, and since 1995 in Russia and Ukraine; elsewhere, no time trends were detected.

CONCLUSIONS

Methodologic differences and potential biases should be considered when comparing these data. HIV prevalence in pregnant women is useful for monitoring the AIDS epidemic and for assessing and improving prevention. Efforts should be made to offer voluntary counseling and testing to women at risk for HIV and provide treatment to those who are infected.

Prevalence of human immunodeficiency virus infection and drug use in pregnant women: a critical review of the literature

Many studies have been undertaken in the last 10 years to determine the prevalence of both human immunodeficiency virus (HIV) infection and drug use in pregnant women. These studies could have a serious impact on the delivery of health care as well as the development of health policy. We provide an overview of the key findings from these studies and a critical review of their strengths and weaknesses. For example, although many prevalence studies were conducted with enough participants to reach statistical significance, flaws in study design limit the generalizability of the findings. In addition, the development of profiles, risk groups, or characteristics was an unsuccessful method of identifying pregnant women at risk for drug use or HIV infection. These findings have implications for the type of screening procedures that are undertaken in the clinical setting and the development of health policy at various levels of government. We also conclude that the issue of stigma and discrimination in relation to drug and HIV testing, as well as race, gender, and socioeconomic status, must be addressed. Finally, we outline how these studies could have a significant effect on the health of pregnant women.

Interpreting HIV seroprevalence data from pregnant women

HIV prevalence estimates for pregnant women from unlinked anonymous surveys are becoming increasingly available and can be used to determine the prevalence of HIV in women in the same population. The ratio of prevalence in pregnant women to that in all women is influenced by HIV-related risk behaviours that are different for pregnant and nonpregnant women and also by differences in fertility level among infected and uninfected women. This ratio is affected by biases that are likely to be culturally and socially specific. A model is proposed for the qualification and quantification of these biases and hence the estimation of general female population prevalence from serosurveillance data on pregnant women.

Impact of incomplete coverage of neonatal dried blood spot screening on estimating HIV-1 seroprevalence

The aim of this study was to determine the extent to which selective under-coverage of births to mothers more likely to be at risk of HIV-1 infection will result in a significant under-estimation of the true neonatal seroprevalence. Census data, local birth statistics, maternity data and data from the prevalence monitoring programme were used to produce a model to predict the effects of under-coverage in the uptake of neonatal metabolic screening which has been observed in babies with a mother of ethnic group black African. The adjustment factor which allows for under-coverage is the relative inclusion ratio (RIR); the probability that samples from a group at different risk of HIV infection were included in the survey divided by the probability of inclusion for samples from all other babies. The RIR was found to be close to unity (0.97), indicating a minimal bias. Under usual conditions only if the relative inclusion ratio (RIR) declined to values of 0.87 or below would there be a substantial bias. Despite some selective under representation, the results obtained from the Unlinked Anonymous HIV Monitoring Programme Dried Blood Spot Survey would seem to identify levels of prevalence in the population of child-bearing women with a good degree of accuracy and remains a useful tool for resource allocation, planning of services, provision of care and counselling.

Temporal and geographical trends of anti-HIV-1 antibodies screening among newborns in Italy, 1990-1993. Italian Collaborative Study Group for HIV Prevalence in Newborns

To describe the dynamic of HIV-1 prevalence in Italian childbearing women and to estimate the future incidence of pediatric AIDS due to vertical transmission, dried-blood specimens collected from a consecutive sample of newborns in all Italian regions were examined for the presence of anti-HIV-1 antibodies (HIV-Ab) after the routine neonatal screening program was completed. Of 555,722 blood samples collected and examined for HIV-Ab between 1990 and 1993, 550 (0.099%) were positive. Nationwide, the HIV seroprevalence decreased between 1990 and 1992 (0.124% in 1990, 0.100% in 1991, 0.085% in 1992), and increased, as compared with that in the previous year, in 1993 (0.096%). In an univariate analysis, HIV seroprevalence was positively was positively associated with being born in regions having higher AIDS cumulative incidence and in metropolitan areas, but negatively associated with year of delivery. In a multiple logistic regression analysis, only the AIDS cumulative incidence level of the delivery area and being born in a metropolitan area remained independently associated with HIV seroprevalence. Our results show significant geographical variation in the spread of HIV infection among childbearing women in Italy and provide useful indications to target prevention and care strategies for HIV-infected women and their children and to estimate the potential impact of implementing programs aimed at preventing vertical transmission of HIV infection.

Mother-to-infant HIV transmission: timing, risk factors and prevention

Identifying when--during pregnancy, delivery or the postnatal period--transmission of human immunodeficiency virus (HIV) from mother to infant usually takes place is critical to the development of methods to prevent maternal-infant transmission. Evidence is reviewed in this paper as to whether transmission occurs prepartum (early or late in gestation), intrapartum, or postpartum with breast feeding. Evidence in support of the notion of prepartum transmission has come from isolation of HIV from aborted fetal organs, comparison of maternal-child viral genotypes and study of neonatal cell-mediated immune responses. Evidence against prepartum transmission is that fewer than half of the children later known to be HIV-infected can be identified by virological tests carried out close to birth. A reduced rate of transmission in infants delivered by Caesarean section, and a reduced risk of transmission to second-born twins delivered vaginally, offers support to the view that intrapartum factors influence the risk of HIV transmission. Transmission through breast feeding can occur if a mother is infected postpartum and seems to pose some additional risk if she is already infected at parturition. The risk of infection increases with the stage of maternal HIV disease, but specific immunological, clinical and viral characteristics need to be investigated further. A clinical trial of zidovudine, used during late pregnancy and delivery and given to the infant at birth, has reported a significant reduction in transmission. Primary prevention of HIV infection in women remains a principal priority.