Chin-Yih Ou

Molecular Epidemiology of HIV Transmission in a Dental Practice

Human immunodeficiency virus type 1 (HIV-1) transmission from infected patients to health-care workers has been well documented, but transmission from an infected healthcare worker to a patient has not been reported. After identification of an acquired immunodeficiency syndrome (AIDS) patient who had no known risk factors for HIV infection but who had undergone an invasive procedure performed by a dentist with AIDS, six other patients of this dentist were found to be HIV-infected. Molecular biologic studies were conducted to complement the epidemiologic investigation. Portions of the HIV proviral envelope gene from each of the seven patients, the dentist, and 35 HIV-infected persons from the local geographic area were amplified by polymerase chain reaction and sequenced. Three separate comparative genetic analyses—genetic distance measurements, phylogenetic tree analysis, and amino acid signature pattern analysis—showed that the viruses from the dentist and five dental patients were closely related. These data, together with the epidemiologic investigation, indicated that these patients became infected with HIV while receiving care from a dentist with AIDS.

Independent introduction of two major HIV-1 genotypes into distinct high-risk populations in Thailand.

To investigate the genetic heterogeneity and epidemiological distribution of human immunodeficiency virus type 1 (HIV-1) in Thailand, we determined proviral sequences for 63 HIV-1-infected patients in various risk groups from all over the country between April and July, 1991. Two distinct genotypes of HIV-1, A and B, were found to segregate by mode of transmission. Of 29 sexually infected patients, 25 (86%) had HIV-1 of genotype A and 4 (14%) had genotype B. Among 29 injecting drug users, probably parenterally infected, only 7 (24%) had genotype A and 22 (76%) had genotype B. This segregation is unlikely to have arisen by chance (p < 0.001). No patient was found to have dual infection. Nucleotide divergence averaged 3.4% among genotype-A-infected patients and 3.5% among genotype-B-infected patients, but 22.0% between the genotypes. 37 of 40 isolates (both genotypes) had the GPGQ tetrapeptide at the tip of the V3 loop, which is common in African HIV-1 strains but rare in North American and European strains, where the GPGR motif predominates. These findings suggest that the waves of HIV-1 infection in injecting drug users and in sexually infected patients in Thailand may not be epidemiologically linked. The nucleotide divergence data point to the separate introductions of the two genotypes in Thailand. Further studies in Thailand and neighbouring countries will be useful in the design and selection of candidate HIV vaccines.

Use of the polymerase chain reaction for early detection of the proviral sequences of human immunodeficiency virus in infants born to seropositive mothers

Abstract The early diagnosis of infection with human immunodeficiency virus (HIV) in infants born to infected mothers is essential for early treatment, but current tests cannot detect HIV infection in newborns because of the presence of maternal antibodies. We used the polymerase chain reaction, a new technique that amplifies proviral sequences of HIV within DNA, to detect HIV infection in peripheral-blood mononuclear cells obtained from infants of seropositive women during the neonatal (age less than 28 days) and postneonatal periods. In blood obtained during the neonatal period, the polymerase chain reaction was positive in five of seven infants in whom the acquired immunodeficiency syndrome (AIDS) later developed (a mean of 9.8 months after the test). The test was also positive in one of eight newborns who later had nonspecific signs and symptoms suggestive of HIV infection (mean follow-up, 12 months). No proviral sequences were detected in neonatal samples from nine infants who remained well (mean fol...

Transmission of Human Immunodeficiency Virus in a Dental Practice

OBJECTIVE To determine if patients of a dentist with the acquired immunodeficiency syndrome (AIDS) became infected with human immunodeficiency virus (HIV) during their dental care and, if so, to identify possible mechanisms of transmission. DESIGN Retrospective epidemiologic follow-up of the dentist, his office practice, and his former patients. SETTING The practice of a dentist with AIDS in Florida. PARTICIPANTS A dentist with AIDS, his health care providers and employees, and former patients of the dentist, including eight HIV-infected patients. MEASUREMENTS Identification of risks for HIV transmission (if present), degree of genetic relatedness of the viruses, and identification of infection control and other office practices. RESULTS Five of the eight HIV-infected patients had no confirmed exposures to HIV other than the dental practice and were infected with HIV strains that were closely related to those of the dentist. Each of the five had invasive dental procedures, done by the dentist after he was diagnosed with AIDS. Four of these five patients shared visit days (P greater than 0.2). Breaches in infection control and other dental office practices to explain these transmissions could not be identified. CONCLUSION Although the specific incident that resulted in HIV transmission to these patients remains uncertain, the epidemiologic evidence supports direct dentist-to-patient transmission rather than a patient-to-patient route.

Highly specific V3 peptide enzyme immunoassay for serotyping HIV-1 specimens from Thailand.

ObjectiveTo develop and evaluate a simple V3 peptide-based enzyme immunoassay (EIA) for large-scale serotyping of HIV-1 specimens from Thailand. DesignSerologic reactivities with synthetic peptides derived from the V3 loop of gp120 were used for typing HIV-1 specimens. MethodsSynthetic peptides PND-A and PND-B, derived from the consensus amino-acid sequences of the V3 loop of gp120 from two major genomic variants of HIV-1 in Thailand (A and B), were evaluated in an EIA on 61 Thai HIV-1 sera for which genotypes had been determined by polymerase chain reaction. The peptide EIA was then applied to sera from 188 HIV-1-infected patients, selected in non-random, convenience samples of known risk groups from four geographic regions of Thailand. ResultsThe sensitivities and specificities of PND-A and PND-B were 86% (30 out of 35) and 96% (25 out of 26) and 92% (24 out of 26) and 94% (33 out of 35), respectively, with 100% predictive values of a monoreactive positive test for both peptides. The assay classified 101 specimens as serotype A, 39 as serotype B, eight as serotype AB (dually reactive), and 40 as untypable (non-reactive). Excluding dual reactors and non-reactors, 92% (77 out of 84) of specimens from patients probably infected by sexual contact were serotype A; conversely, 76% (28 out of 37) of injecting drug users were serotype B. ConclusionThe serologic results corroborated previous findings, in a smaller subset of samples, of an apparent segregation of viral subtypes by mode of transmission, suggesting two separate HIV-1 epidemics in Thailand. This peptide EIA could be a valuable epidemiologic tool in determining the dynamics of the rapid spread of HIV-1 in Thailand.

Dried blood spots collected on filter paper: an international resource for the diagnosis and genetic characterization of human immunodeficiency virus Type-1

The collection of dried blood spots (DBS) on filter paper provides a powerful approach for the development of large-scale, population-based screening programs. DBS methods are particularly valuable in developing countries and isolated rural regions where resources are limited. Large numbers of field specimens can be economically collected and shipped to centralized reference laboratories for genetic and (or) serological analysis. Alternatively, the dried blood can be stored and used as an archival resource to rapidly establish the frequency and distribution of newly recognized mutations, confirm patient identity or track the origins and emergence of newly identified pathogens. In this report, we describe how PCR-based technologies are beginning to interface with international screening programmes for the diagnosis and genetic characterization of human immunodeficiency virus type 1 (HIV-1). In particular, we review recent progress using DBS specimens to resolve the HIV-1 infection status of neonates, monitor the genetic evolution of HIV-1 during early infancy and establish a sentinel surveillance system for the systematic monitoring of HIV-1 genetic variation in Asia.

A prospective population-based study of HIV perinatal transmission.

Objective:To estimate the perinatal HIV transmission rate and describe the natural history of infant HIV infection in a situation in which HIV status is known in more than 95% of delivering women. Design:A cohort of HIV-exposed infants born between 7 July 1987 and 30 June 1990, whose mothers were identified by routine voluntary universal HIV testing, were followed using clinical and laboratory measures. Setting:Grady Memorial Hospital, a major health-care site for individuals of lower socioeconomic status in Atlanta, Georgia, USA, with approximately 7000 deliveries per year. Patients:HIV-exposed infants (n=165), 98% of whom were African American. Results:Annual maternal HIV seroprevalence increased from 0.58 to 0.86%. The annual proportion of HIV-positive women having a second delivery increased from 4.3 to 25%. Clinical outcome was known for 132 out of 165 infants (22 infected and 110 uninfected), the transmission rate was 17% (confidence interval, 11–24%). The rate declined to 11% by the third year of the study. Gestational growth, prematurity and mode of delivery were unrelated to infant outcome. There was a trend for intravenous drug use to be more common in mothers of infected infants (P=0.08). After 35 months median follow-up of infected infants, eight out of 22 (36%) had an opportunistic infection (seven Pneumocystis carinii pneumonia); three out of 22 (14%) had lymphocytic interstitial pneumonia, and 10 out of 22 (45%) were asymptomatic or had only nonspecific symptoms. Cumulative mortality in infected infants was 9, 32 and 32% by 1, 2 and 3 years of age, respectively. Conclusion:In this cohort of HIV-exposed infants, perinatal HIV transmission was 17% overall. Factors affecting the transmission rate and possible future changes in the rate require further study.

Diagnosis of Perinatal Human Immunodeficiency Virus Infection by Polymerase Chain Reaction and p24 Antigen Detection after Immune Complex Dissociation in an Urban Community Hospital

Results of polymerase chain reaction (PCR) and p24 antigen detection after immune complex dissociation (p24-ICD) were compared with antibody results after 18 months of age for human immunodeficiency virus (HIV) diagnosis in 345 prospectively followed, perinatally exposed infants. Of 59 infected and 286 uninfected infants tested at 1-6 months of age, sensitivity and specificity were, respectively, 100% and > 97% for PCR and 90% and > 97% for p24-ICD. Testing was done on > or = 2 occasions in the first 6 months of life in 43 infected infants; 77% had > or = 2 positive results with the same test. Of these infants, 68% had 2 positive p24-ICD tests. In uninfected infants, 96% had only negative tests; none had > 1 positive. By 6 months, all uninfected infants with > or = 2 PCR results could have been diagnosed. HIV status can be determined by PCR by age 6 months in most HIV-exposed infants. p24-ICD should not be used alone, because of its lower sensitivity, but may be useful in areas without advanced laboratory support.

Lack of detectable human immunodeficiency virus infection in antibody-negative children born to human immunodeficiency virus-infected mothers.

More than one-half of the children born to women with human immunodeficiency virus (HIV) infection are not infected with HIV. Most of these children, although born antibody-positive, lose maternal antibody and remain asymptomatic. However, it has been unclear how many antibody-negative children of HIV-infected women may truly be infected despite the loss of passively acquired maternal antibody. One hundred nine children who lost maternal antibody after birth to HIV-infected women recruited in four United States maternal HIV transmission studies were examined for HIV infection. Polymerase chain reaction (PCR) was used to determine whether children had HIV proviral DNA in peripheral blood mononuclear cells. A total of 268 samples from 109 children were tested. Clinical status and other laboratory findings were also evaluated. The median age at last follow-up was 25 months (range, 12 to 48 months). One hundred seven (98%) children were negative by PCR on all samples tested. None (95% confidence interval, 0.0 to 1.9%) of 109 children had a repeatedly positive PCR. Two children had single positive PCR results that could not be confirmed on subsequent testing. No other laboratory or clinical findings supported HIV infection in either of these children. The loss of HIV antibody in an asymptomatic child born to an HIV-infected woman strongly suggests that the child is not infected with HIV. Single positive PCR results, particularly in the absence of other clinical or laboratory evidence of HIV infection, should not be used alone to diagnose HIV infection.

MagaZorb: A simple tool for rapid isolation of viral nucleic acids

Abstract Effective isolation of nucleic acids from samples containing viral materials is an essential step for accurate diagnosis of viral infections. The necessity of this critical step before analytical identification and diagnosis of viral infections is paramount to screening programs and to identifying and monitoring epidemics and pandemics. With molecular assays rapidly evolving into routine practice, clinical laboratories face several challenges, including presence of small amounts of viral nucleic acids in abundant levels of genomic DNA and total RNA, processing of various sample types, and carry-over of polymerase chain reaction inhibitors, which could significantly affect polymerase chain reaction and microarray results. MagaZorb nucleic acid isolation technology overcomes these challenges and offers a simple and reliable method for isolation of highquality and high-yield nucleic acids. Although the MagaZorb technology is readily adaptable to automated platforms, it is also well suited to laboratories in remote areas of resource-poor countries, because a simple magnet is the only device required to perform the procedure manually. Performance characteristics and clinical application of the MagaZorb technology are briefly described here.