A rapid test for the detection of human immunodeficiency virus antibodies in cord blood

The performance of 5 rapid HIV tests using whole blood in infants and children: selecting a test to achieve the clinical objective

BACKGROUND

Rapid tests have the potential to improve the identification of HIV-infected children in resource-limited settings. However, they remain underutilized because of a lack of data on their performance in the field using whole blood specimens. This study aimed to assess the accuracy of rapid tests for detecting HIV exposure, excluding HIV infection in HIV-exposed infants, and diagnosing HIV infection in children older than 18 months of age.

METHODS

Five rapid tests (First Response, Pareekshak, Determine, Smart Check, and Insti) were performed using whole blood from children enrolled in a multisite, cross-sectional study in South Africa. HIV enzyme-linked immunosorbent assay and DNA polymerase chain reaction results defined HIV exposure and infection, respectively, and were the standards used for comparison.

RESULTS

Of the 851 children enrolled, 186 (21.9%) were infected with HIV. For detecting HIV exposure, Determine demonstrated the highest sensitivity of 99.3% (95% confidence interval, 98.0-99.8) in early infancy, but sensitivity declined with age as seroreversion occurred. After 8 months of age, all tests except First Response excluded HIV infection in 82% to 100% of HIV-uninfected infants and, in conjunction with a clinical assessment, did not miss any HIV-infected children. Insti was the only test that detected all HIV-infected infants, albeit on the smallest number of samples. The performance of all rapid tests in children older than 18 months of age was similar to that in adults.

CONCLUSIONS

Determine was the only rapid test that had a high enough sensitivity for detecting HIV exposure in early infancy, but it identified seroreversion later in life than the other tests. Insti warrants further investigation for both indications.

Detection of cytomegalovirus in the meconium of infected newborns by polymerase chain reaction

OBJECTIVE

Congenital cytomegalovirus (CMV) infection is a leading cause of hearing loss and mental retardation throughout the world. Detection of the CMV DNA by polymerase chain reaction (PCR) offers a sensitive, rapid, and specific means of identification. Meconium, the stool formed in utero, may be an ideal specimen for CMV detection. The objective of this study was to develop a PCR-based methodology for the detection of CMV in the meconium of neonates.

METHODS

Meconium was collected from 10 newborn infants (seven with positive viral cultures and three uninfected infants born to CMV-seropositive mothers). For each, DNA was isolated from meconium by organic extraction and attachment to a DNA-binding matrix, and PCR was performed using amplimers specific for the major intermediate early (MIE) and late antigenic (LA) regions of CMV.

RESULTS

Gel electrophoresis demonstrated an anticipated PCR product of 250 base pairs (bp) corresponding to the MIE region of CMV in all infected and positive control meconium samples. Furthermore, a single band of 150 bp corresponding to the LA region of CMV was also amplified in several of the infected infants. Conversely, no amplification of these antigenic regions was noted in either uninfected infants born to CMV-seropositive mothers or negative controls.

CONCLUSIONS

CMV is present within the meconium of infected neonates and is readily detectable by PCR.

Umbilical cord blood: an alternative to the transplantation of bone marrow stem cells

Recent in vitro analyses of human UCB have demonstrated the potential of UCB as a source for haematopoietic stem and progenitor cell harvest. Clinical data have further indicated that UCB can be given in vivo to fully and partially HLA-matched siblings or non-familial recipients for marrow reconstitution in genetic disorders as well as malignancies. In comparison to adult peripheral blood, UCB displayed decreased immune responses to alloantigens and was enriched in the numbers of CD34+ progenitor cells with high proliferative and long-term marrow reconstituting potential. Cord blood banks now store large transplantable resources of UCB that are analysed with respect to immunological parameters. Cryopreserved UCB cells may fill the gap in finding a stem-cell transplant for patients who lack a matched related or unrelated donor when a bone marrow transplant is needed.