Epstein-Barr virus DNA in the blood of infants, young children, and adults by age and HIV status.

Polymerase chain reaction (PCR) methodology was used to detect Epstein-Barr virus (EBV) DNA in peripheral blood mononuclear cells (PBMCs) from children and adults whose HIV status (i.e., infected or uninfected) is known. Initial EBV infections especially occurred in children between the ages of 7 and 24 months. EBV-positive children with vertically acquired HIV infection tended to have a detectable blood level of EBV DNA for a period of years, and their EBV DNA blood levels often exceeded 10,000 copies/0.1 ml of blood--hundreds of times higher than levels typically found in EBV-positive, HIV-uninfected children of the same age. EBV DNA was found in PBMCs in 26% of 49 HIV-infected mothers who were sampled during their pregnancy, but the median EBV DNA level in their EBV-positive samples was low--only 50 copies/0.1 ml blood. In limited tests with specimens from children infected with both HIV and EBV, high blood levels of EBV DNA unexpectedly appeared to be associated with decreased blood levels of HIV DNA (p = .063).

HIV DNA blood levels in vertically infected pediatric patients: variations with age, association with disease progression, and comparison with blood levels in infected mothers.

Blood levels of HIV DNA in our vertically infected pediatric patients typically followed a characteristic age-related pattern: continuously increasing with increasing age to a peak between ages 4 and 8 months, and thereafter rather steadily declining. Median HIV DNA levels peaked about 3 months earlier in children who by age 24 months developed more severe rather than less severe HIV disease. Children at particular risk of developing severe HIV disease by age 24 months commonly had > 800 HIV DNA copies per 0.1 ml of blood at age 3 weeks to 2 months, > 1,000 copies at 2 to 4 months, and > 2,500 copies at ages 4 to 6 months. Near the time of delivery mothers who transmitted HIV had significantly higher median blood levels of HIV DNA than mothers who did not transmit, but median HIV DNA levels in infected mothers as a group were low compared with those in pediatric patients > or = 1 month of age.

Human immunodeficiency virus infection in infants during the first 2 months of life. Reliable detection and evidence of in utero transmission.

OBJECTIVE: To evaluate the clinical utility of a polymerase chain reaction (PCR) method for detecting human immunodeficiency virus (HIV) infection in infants 2 months of age or younger who were born to HIV-positive mothers. DESIGN: Prospective, longitudinal study lasting 3 years. The PCR tests were performed with coded peripheral blood mononuclear cell lysates, and results were compared with findings using Centers for Disease Control and Prevention (CDC) (Atlanta, Ga) criteria defining HIV infection in children. SETTING: Hospitals, particularly a pediatric hospital in Washington, DC. PATIENTS: Newborns, young infants, and HIV-infected mothers. OUTCOME MEASURE: Presence or absence of pediatric HIV infection using CDC criteria compared with a diagnosis based on the detected presence or absence of HIV proviral DNA using PCR testing. RESULTS: One or more blood samples obtained by 62 days of age from 30 (94%) of 32 HIV-infected infants were positive for HIV by routine PCR testing. Blood samples from 32 infants now confirmed to be uninfected tested negative for HIV. Human immunodeficiency virus DNA was detected in blood samples obtained within 48 hours of birth from eight of nine infected infants. In six of these newborns as well as most older infants, HIV DNA was present in such quantity that it was detectable in specimens equivalent to 0.01 mL or less of the original blood sample. CONCLUSIONS: Our PCR procedure can reliably detect the presence or absence of HIV infection during the first 2 months of life. The frequent presence and not uncommon high titer of HIV DNA within 48 hours of birth suggest that much of the transmission of HIV from mother to infant occurs well before birth.

Detection of human immunodeficiency virus type 1 infection in young pediatric patients by using polymerase chain reaction and biotinylated probes.

Polymerase chain reaction (PCR) testing using up to four primer pairs and biotinylated probes was 97.9% sensitive (188 of 192 specimens positive) and 100% specific (267 of 267 specimens negative) for detecting the presence or absence of human immunodeficiency virus (HIV) DNA in peripheral blood mononuclear cells from pediatric patients whose HIV status has been confirmed. SK38/39 and SK145/150 were the most sensitive primer pairs, respectively detecting HIV DNA in 95.6 and 95.9% of peripheral blood mononuclear cell specimens from HIV-infected children and collectively detecting all adequately tested PCR-positive specimens. Primer pairs SK29/30 and SK68/69 respectively detected HIV DNA in only 76.4 and 76.6% of HIV-positive specimens. Among infants born to HIV-seropositive mothers, 30 who subsequently were confirmed to be infected were sampled when they were less than or equal to 6 months of age; in all but one infant, HIV DNA was found in the first specimen collected. Among the nine youngest infected infants tested, all were PCR positive by 38 days of age. PCR methods thus have reliably detected vertically transmitted HIV infection early in life.

Glucosidase I, a transmembrane endoplasmic reticular glycoprotein with a luminal catalytic domain.

We have analyzed the functional domain structure of rat mammary glucosidase I, an enzyme involved in N-linked glycoprotein processing, using biochemical and immunological approaches. The enzyme contains a high mannose type sugar chain that can be cleaved by endo-beta-N-acetyl-D-glucosaminidase H without significantly affecting the catalytic activity. Based on trypsin digestion pattern and the data on membrane topography, glucosidase I constitutes a single polypeptide chain of 85 kDa with two contiguous domains: a membrane-bound domain that anchors the protein to the endoplasmic reticulum and a luminal domain. A catalytically active 39-kDa domain could be released from membranes by limited proteolysis of saponin-permeabilized membranes with trypsin. This domain appeared to contain the active site of the enzyme and had the ability to bind to glucosidase I-specific affinity gel. Phase partitioning with Triton X-114 indicated the amphiphilic nature of the native enzyme, consistent with its location as an integral membrane protein, whereas the 39-kDa fragment partitioned in the aqueous phase, a characteristic of soluble polypeptide. These results indicate that glucosidase I is a transmembrane protein with a luminally oriented catalytic domain. Such an orientation of the catalytic domain may facilitate the sequential processing of asparagine-linked oligosaccharide, soon after its transfer en bloc by the oligosaccharyl transferase complex in the lumen of endoplasmic reticulum.

Studies on hormonal modulation of asparagine-linked glycoprotein biosynthesis in explant cultures of rat mammary gland.

Glucosidase I has been purified to homogeneity and polyclonal antibodies against the enzyme have been prepared. The anti-glucosidase I antibodies recognized a single band of 85 kDa on western blot at a dilution as high as 1:2000 and also inhibited the enzyme activity, suggesting the specificity of the antibodies. Con A-Sepharose binding experiment indicates that this enzyme itself is a high mannose type N-linked glycoprotein. The increase in the electrophoretic mobility of 85 kDa band following digestion with endoglycosidase H and F strengthened this observation. The presence of any O-linked sugar attached covalently to glucosidase I could not be detected by binding assays with O-linkage specific biotinylated lectins. The studies on developmental regulation suggest that the synthesis of glucosidase I is modulated with the ontogeny of the gland. Lactogenic hormones, viz. insulin, hydrocortisone and prolactin, appeared to regulate the synthesis of glucosidase I. The possible role of these hormones in the overall regulation of protein N-glycosylation has been discussed.

Developmental regulation of glucosidase I, an enzyme involved in the processing of asparagine-linked glycoproteins in rat mammary gland.

Glucosidase I involved in the processing of N-linked glycoproteins was purified to homogeneity from the lactating rat mammary gland. The purified enzyme exhibited a single band at 85 kDa on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Polyclonal antibodies raised against the enzyme recognized a similar band on Western blots and also inhibited the enzyme activity. The enzyme levels gradually increased until the midlactation stage and thereafter declined sharply during the period of postlactation. A similar profile of the levels of immunoreactive glucosidase I was observed. These findings suggest that the accumulation of glucosidase I is modulated as a function of gland ontogeny. The results on hormonal regulation of glucosidase I indicate that the synthesis of the enzyme is stimulated by a combination of insulin, hydrocortisone, and prolactin; additionally, epidermal growth factor may play a role in this regulation. The above observation was substantiated by immunoprecipitation of [35S]methionine-labeled microsomal extracts with anti-glucosidase I antibodies. The immunoprecipitation of soluble extracts from [35S]methionine-labeled tissue with anti-rat alpha-lactalbumin antibodies indicates that these hormones not only stimulate the synthesis of alpha-lactalbumin but also play an important role in its glycosylation.

Purification and characterization of UDP-N-acetyl-D-glucosamine:dolichol phosphate N-acetyl-D-glucosamine-1-phosphate transferase involved in the biosynthesis of asparagine-linked glycoproteins in the mammary gland.

The GlcNAc-1-P-transferase that initiates the dolichol cycle for the biosynthesis of asparagine-linked glycoproteins has been purified from the lactating bovine mammary gland. After solubilization from microsomes with 0.25% Nonidet P-40, the enzyme activity was stabilized with 20% glycerol, 20 micrograms/ml phosphatidylglycerol, 5 microM dolichol phosphate, and 2.5 microM UDP-GlcNAc. The purification protocol involved (NH4)2SO4 precipitation, gel filtration on Sephacryl S-300, DEAE-TSK, and hydroxylapatite chromatography. The purified enzyme was devoid of several readily detectable glycosyltransferases of the dolichol cycle. It showed two bands (A, 50 kDa and B, 46 kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis after either Coomassie Blue or silver staining. Antisera (anti-A and anti-B) raised against individual bands A and B inhibited the enzyme activity in solubilized microsomes. Each of the partially purified antibodies recognizes both bands A and B on Western blots of the enzyme; with the solubilized microsomes, the antibodies also recognize an additional polypeptide of approximately 70 kDa. When radioiodinated microsomes were immunoprecipitated with anti-B and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, again bands of 46, 50, and 70 kDa were observed. The peptide mapping of 50 and 46 kDa bands of the purified enzyme by chemical cleavage with N-chlorosuccinimide gave similar fragmentation patterns. The results indicate that either 70 kDa band is a precursor form of the enzyme or this polypeptide, representing the native enzyme or its subunit, is proteolyzed to smaller, enzymatically active peptide(s) of 50 and 46 kDa during purification despite the inclusion of several inhibitors against serine-proteases in all buffers used for tissue homogenization and enzyme purification. A number of properties of the purified enzyme, including its specific activation by Man-P-Dol were also characterized.