Biomedical subjects

Y Tang

Publications and source records attributed to Y Tang.

At least 37 records · Page 2Linked to original sources

PubMed2005

A hypoxia-inducible vigilant vector system for activating therapeutic genes in ischemia.

Hypoxia represents an endogenous pathophysiological signal underlying cell growth, adaptation and death in a variety of diseases, including ischemic heart diseases, stroke and solid tumors. A vigilant vector system depends on a gene switch which can sense the hypoxia signal occurring in ischemic events and turn on/off protective gene expressions when necessary. This system uses the oxygen-dependent degradation domain derived from hypoxia-inducible factor 1alpha as the hypoxia sensor and a double-vector system as signal amplifier. For treating ischemic heart diseases, a cardiac-specific MLC-2v promoter is used to deliver transgenes specifically to the heart. When tested in cardiomyocyte cultures, it produced a rapid and robust gene induction upon exposure to low oxygen. In a mouse model for myocardial infarction, the vigilant vectors turned on therapeutic genes such as heme oxygenase-1 in response to ischemia, significantly reduced apoptosis in the infarct area and improved cardiac functions. The hypoxia-regulated gene transfer afforded by the vigilant vectors may provide a powerful tool for delivering therapeutic proteins specifically to ischemic tissues with optimal physiological control.

Animals↗

PubMed2005

Mobile classification in microarray experiments.

In a homogeneous group of samples, there are genes whose expression variations can be attributed to factors other than experimental errors. These factors can include natural biological oscillations or metabolic processes. These genes are rarely classified as 'interesting' based on their variability profile. However, their dynamic behaviour can tease out important clues about naturally occurring biological processes in the organism under study and can be used for group classification. Dynamical discriminate function analysis was developed on the concept that stable classification parameters (roots) can be derived from highly variable gene-expression data. Stability of these combinations implies a strongly compensatory relationship that may divulge functional interconnections.

Colitis, Ulcerative↗

PubMed2005

Pharmacological profile of a novel, non-TZD PPARgamma agonist.

AIM: The purpose of this study was to characterize a novel, non-thiazolidinedione (TZD) peroxisome proliferator-activated receptor (PPAR)gamma agonist, RWJ-348260, via both in vitro and in vivo approaches. METHODS: The in vitro PPARgamma activities of RWJ-348260 were assessed in PPARgamma-GAL4 co-transfection assay, PPARgamma receptor binding assay, aP2 gene induction assay and preadipocyte differentiation assay. The in vivo efficacy of the compound was determined in rodent genetic diabetes models [ob/ob mouse, db/db mouse and Zucker diabetic fatty (ZDF) rat] following multiple days of oral administration. RESULTS: RWJ-348260 selectively activated PPARgammain vitro. In vivo, RWJ-348260 produced significant decreases in plasma glucose, HbA1c, insulin and triglyceride levels. RWJ-348260 also dose-dependently improved oral glucose tolerance. In db/db mice, the compound up-regulated PPARgamma target genes in white adipose tissues. RWJ-348260 produced a lower extent of hepatocyte lipid deposition and a smaller increase in liver weight compared to rosiglitazone in db/db mice. While RWJ-348260 effectively normalized hyperglycaemia and dyslipidaemia, it did not change haematocrit, transaminase, alkaline phosphatase, total bilirubin levels or liver weights in ZDF rats. CONCLUSIONS: RWJ-348260 is a potent PPARgamma agonist with efficacious antidiabetic activity in diabetic animal models. The compound has an improved side-effect profile compared to rosiglitazone.

Adipocytes↗

PubMed2005

Development of antigen-capture enzyme-linked immunosorbent assay and RT-PCR for detection of turkey astroviruses.

Turkey astrovirus (TAstV) is an important agent of poult enteritis. The diagnosis of astroviruses has been dependent mainly on electron microscopy (EM) or immune EM (IEM). To develop other simple, rapid, and reliable diagnostic assays, two antigen-capture enzyme-linked immunosorbent assays (AC-ELISAs), polyclonal AC-ELISA and monoclonal AC-ELISA, were developed in this study. Monoplex and multiplex reverse transcription-polymerase chain reactions (RT-PCRs) were also developed using nondegenerate primer sets specific to the capsid region and degenerate primer pairs specific to the polymerase area of two TAstV. EM was included for comparison. Fecal or intestinal contents samples from naturally and experimentally infected poults with enteritis were examined using the developed assays. The polyclonal AC-ELISA had higher sensitivity and wider detection spectrum than the monoclonal AC-ELISA with group-specific monoclonal antibody (MAb), whereas the monoclonal AC-ELISA had very high specificity but lower sensitivity, which was estimated at 0.06 microg of viral proteins. Small round viruses (SRV) that could be astroviruses or other small viruses were detected in 34.4% of the samples examined by EM. The monoplex RT-PCR results amplified with primers SRV-1-3 and SRV-1-5 revealed that the positive rate of astroviruses was 45.3%, which was 10.9% higher than that of EM even if other SRVs were not excluded. Multiplex RT-PCR with SRV-1-3 and SRV-1-5 and AFCP-F1 and AFCP-R1 and the monoplex RT-PCR with degenerate primers verified that the positive rate of astroviruses was 59.4%, which was 25% higher than that of EM. Both RT-PCRs showed good specificity and wider detection spectrum compared with earlier published data.

Animals↗

PubMed2005

Isolation and characterization of H3N2 influenza A virus from turkeys.

Five 34-wk-old turkey breeder layer flocks in separate houses of 2550 birds each in a single farm in Ohio experienced a drop in egg production from late January to early February 2004. Tracheal swabs (n = 60), cloacal swabs (n = 50), and convalescent sera (n = 110) from the flocks were submitted to the laboratory for diagnostics. Virus isolation was attempted in specific-pathogen free embryonating chicken eggs and Vero and MDCK cells. Virus characterization was performed using agar gel immunodiffusion, the hemagglutination test, the hemagglutination inhibition test, the virus neutralization test, reverse transcription-polymerase chain reaction, sequencing, and phylogenetic analysis. A presumptive influenza virus was successfully propagated and isolated on the first passage in MDCK cells, but initially not in Vero cells or specific-pathogen free chicken embryos. After two passages in MDCK cells, it was possible to propagate the isolate in specific-pathogen free chicken embryos. Preliminary sequence analysis of the isolated virus confirmed that it was influenza A virus with almost 100% (235/236) identity with the matrix gene of a swine influenza A virus, A/Swine/Illinois/100084/01 (H1N2). However, it was not possible to subtype the virus using conventional serotyping methods. The results of genetic characterization of the isolated virus showed that it was the H3N2 subtype and was designated as A/Turkey/OH/313053/04 (H3N2). Phylogenetic analysis of the eight gene segments of the virus showed that A/Turkey/OH/313053/04 (H3N2) isolate was most closely related to the triple-reassortant H3N2 swine viruses [A/Swine/WI/14094/99 (H3N2)] that have been circulating among pigs in the United States since 1998, which contains gene segments from avian, swine, and human viruses. The A/Turkey/OH/313053/04 (H3N2) isolated from turkeys in this study was classified as a low pathogenic avian influenza A virus because it only caused a drop in egg production with minor other clinical signs and no mortality.

Animals↗

PubMed2005

Molecular characterization of the capsid gene of two serotypes of turkey astroviruses.

Astrovirus infections mainly cause acute gastroenteritis in children and young animals. Human astroviruses are well characterized antigenically and genetically. However, information on turkey astroviruses is limited. We isolated two astroviruses (TAstV1987 and TAstV2001) from turkeys and classified them as two different serotypes using a virus neutralization test. To elucidate the differences between these two isolates at the molecular level, further genetic characterization and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis were carried out. The sequences of the complete capsid protein gene of these two isolates were obtained by cloning and sequencing. The percentage nucleotide and predicted amino acid identities for these two sequences along with those of 16 other capsid protein gene sequences from human and animal astroviruses retrieved from GenBank were calculated using MegAlign. The results showed that TAstV1987 and TAstV2001 had 73.3% nucleotide and 82.8% amino acid identities, respectively. An unrooted Neighbor-joining phylogenetic tree of these sequences was generated using MEGA 3 software with 1000 bootstrap replicates. The results of evolutionary analysis showed that TAstV1987 was closely related genetically to another virus, designated TAstV-2, whereas TAstV2001 was not as close to TAstV-2 as TAstV1987. The analysis of the capsid proteins of the two viruses by SDS-PAGE revealed that they had different band patterns, indicating that their capsid proteins consisted of different viral proteins. The findings in this study revealed the molecular differences in the capsid protein gene of TAstV1987 and TAstV2001, which may provide the molecular basis of the antigenic differences between these two serotypes of turkey astroviruses.

Amino Acid Sequence↗

PubMed2005

Sonic hedgehog, the penis and erectile dysfunction: a review of sonic hedgehog signaling in the penis.

The sinusoid anatomy of the penis is complex and requires complicated interaction between smooth muscle and endothelium in order to maintain homeostasis in the adult. The morphogen, Sonic hedgehog (Shh), is a crucial regulator of these processes, along with its down stream targets patched (Ptc), Hox, bone morphogenetic proteins (BMP's), vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS). Shh is critical for patterning and establishing tissue identity of the penis during embryonic development, is a crucial regulator of penile postnatal differentiation of the sinusoid morphology of the corpora cavernosa, and plays a fundamental role in maintaining sinusoidal structures pertinent to erectile function in the adult rat. Shh and its targets are active in human penes, and decreased in human diabetic penes in parallel with observations in the rat, thus lending clinical significance to the role of abnormal Shh signaling in erectile dysfunction (ED). Application of exogenous Shh protein to rat corpora cavernosa, induces VEGF and NOS proteins, suggesting a potential mechanism through which decreased Shh protein can cause ED. The studies outlined in this review provide in depth analysis of the Shh pathway and signal transduction, its role in penile development, how Shh signaling is altered in a rat model of ED and neuropathy, how abnormal Shh signaling can cause ED, and the clinical significance of the Shh pathway to human ED. These studies will provide valuable insight, at the molecular level, into understanding the mechanisms that under lie ED and lead to new treatment strategies for diabetic impotence.

Animals↗

PubMed2004

Chronic exposure to high glucose impairs bradykinin-stimulated nitric oxide production by interfering with the phospholipase-C-implicated signalling pathway in endothelial cells: evidence for the involvement of protein kinase C.

AIMS/HYPOTHESIS: Overwhelming evidence indicates that endothelial cell dysfunction in diabetes is characterised by diminished endothelium-dependent relaxation, but the matter of the underlying molecular mechanism remains unclear. As nitric oxide (NO) production from the endothelium is the major player in endothelium-mediated vascular relaxation, we investigated the effects of high glucose on NO production, and the possible alterations of signalling pathways implicated in this scenario. METHODS: NO production and intracellular Ca(2+) levels ([Ca(2+)](i)) were assessed using the fluorescent probes 4,5-diaminofluorescein diacetate and fura-2 respectively. RESULTS: Exposure of cultured bovine aortic endothelial cells to high glucose for 5 or 10 days significantly reduced NO production induced by bradykinin (but not by Ca(2+) ionophore) in a time- and dose-dependent manner. This was probably due to an attenuation in bradykinin-induced elevations of [Ca(2+)](i) under these conditions, since a close correlation between [Ca(2+)](i) increases and NO generation was observed in intact bovine aortic endothelial cells. Both bradykinin-promoted intracellular Ca(2+) mobilisation and extracellular Ca(2+) entry were affected. Moreover, bradykinin-induced formation of Ins(1,4,5)P(3), a phospholipase C product leading to increases in [Ca(2+)](i), was also inhibited following high glucose culture. This abnormality was not attributable to a decrease in inositol phospholipids, but possibly to a reduction in the number of bradykinin receptors. The alterations in NO production, the increases in [Ca(2+)](i), and the bradykinin receptor number due to high glucose could be largely reversed by protein kinase C inhibitors and D: -alpha-tocopherol (antioxidant). CONCLUSIONS/INTERPRETATION: Chronic exposure to high glucose reduces NO generation in endothelial cells, probably by impairing phospholipase-C-mediated Ca(2+) signalling due to excess protein kinase C activation. This defect in NO release may contribute to the diminished endothelium-dependent relaxation and thus to the development of cardiovascular diseases in diabetes.

Animals↗

PubMed2004

HIV evolution: CTL escape mutation and reversion after transmission.

Within-patient HIV evolution reflects the strong selection pressure driving viral escape from cytotoxic T-lymphocyte (CTL) recognition. Whether this intrapatient accumulation of escape mutations translates into HIV evolution at the population level has not been evaluated. We studied over 300 patients drawn from the B- and C-clade epidemics, focusing on human leukocyte antigen (HLA) alleles HLA-B57 and HLA-B5801, which are associated with long-term HIV control and are therefore likely to exert strong selection pressure on the virus. The CTL response dominating acute infection in HLA-B57/5801-positive subjects drove positive selection of an escape mutation that reverted to wild-type after transmission to HLA-B57/5801-negative individuals. A second escape mutation within the epitope, by contrast, was maintained after transmission. These data show that the process of accumulation of escape mutations within HIV is not inevitable. Complex epitope- and residue-specific selection forces, including CTL-mediated positive selection pressure and virus-mediated purifying selection, operate in tandem to shape HIV evolution at the population level.

Adult↗

PubMed2004

Postnatal growth of cardiomyocytes in the left ventricle of the rat.

We studied the development of myocytes and interstitium using perfusion-fixed left ventricles obtained from normal female Wistar rats at 5 days (n = 5), 25 days (n = 5), and 125 days (n = 5) of age. Using design-based stereological methods and light microscopy, we estimated the following parameters: volume of left ventricle made up by myocytes, myocyte nuclei, and interstitium; total numbers of myocyte and non-myocyte nuclei; mean volumes of myocyte nuclei; the total volume, surface area, and length of fibers; and the mean star volumes of fibers. Some derived parameters were also calculated, namely, the mean myocardium volume per nucleus and the mean fiber cross-sectional area. We found that postnatal myocyte growth after day 5 in the young rat is largely hypertrophic, while interstitial growth is hyperplastic. The increase in left ventricular mass was 10-fold over the ages studied, whereas total length, surface area, and volume of fibers increased approximately 3-, 8-, and 11-fold over the period. Relative rates of growth implied that fiber growth was dominated by an increase in length compared to other dimensions. The total number of myocyte nuclei ( approximately 30 x 10(6)) did not change between 5 and 25 days of age, but then almost doubled in 125-day-old rats. The number of non-myocyte nuclei increased 9-fold over the period studied in an exponential manner. The mean myocyte nucleus volume tripled between the ages of 5 and 25 days and then remained the same. The volume-weighted mean nucleus volume was highly variable and showed no significant trend with age. Our results provide support for the claim made by some researchers that myocyte proliferation had ceased by day 5 after birth, but do not provide evidence for binucleation of myocytes between 5 and 25 days after birth. Reported numbers of myocyte nuclei express a net growth and do not rule out both myocyte death and creation throughout the early postnatal period. We clearly detect an increase in the number of myocyte nuclei from 25 to 125 days but are not able to state whether this increase reflects myocyte proliferation or myocyte binucleation. To determine this would require special double-staining techniques to delineate intercalated discs and myocyte membranes. Our results agree very well with the limited data available from other studies that have used unbiased stereology. It is important to use unbiased designs that consider anisotropy as well as heterogeneity of the heart in sampling schemes, and to determine absolute quantities to avoid problems associated with interpreting changes in density (the "reference trap").

Age Factors↗

PubMed2004

5alpha-Androstane-3alpha,17beta-diol activates pathway that resembles the epidermal growth factor responsive pathways in stimulating human prostate cancer LNCaP cell proliferation.

5alpha-Androstane-3alpha,17beta-diol (3alpha-diol) is considered to have no androgenic effects in androgen target organs unless it is oxidized to 5alpha-dihydrotestosterone (5alpha-DHT). We used microarray and bioinformatics to identify and compare 3alpha-diol and 5alpha-DHT responsive gene in human prostate LNCaP cells. Through a procedure called 'hypervariable determination', a similar set of 30 responsive genes involving signal transduction, transcription regulation, and cell proliferation were selected in 5alpha-DHT-, 3alpha-diol-, and epidermal growth factor (EGF)-treated samples. F-means cluster and networking procedures showed that the responsive pattern of these genes was more closely related between 3alpha-diol and EGF than between 5alpha-DHT and 3alpha-diol treatments. We conclude that 3alpha-diol is capable of stimulating prostate cell proliferation by eliciting EGF-like pathway in conjunction with androgen receptor pathway.

Anabolic Agents↗

PubMed2004

Valproic acid blood genomic expression patterns in children with epilepsy - a pilot study.

OBJECTIVE: Valproic acid (VPA) is a commonly used anticonvulsant with multiple systemic effects. The purpose of this pilot study is to examine the blood genomic expression pattern associated with VPA therapy in general and secondly VPA efficacy in children with epilepsy. MATERIALS AND METHODS: Using oligonucleotide microarrays, gene expression in whole blood was assessed in pediatric epilepsy patients following treatment with VPA compared with children with epilepsy prior to initiation of anticonvulsant therapy (drug free patients). RESULTS: The expression of 461 genes was altered in VPA patients (n = 11) compared with drug free patients (n = 7), among which a significant number of serine threonine kinases were down-regulated. Expression patterns in children seizure free on VPA therapy (n = 8) demonstrated 434 up-regulated genes, many in mitochondria, compared with VPA children with continuing seizures (n = 3) and drug free seizure patients (n = 7). CONCLUSION: VPA therapy is associated with two significant and unique blood gene expression patterns: chronic VPA monotherapy in general and a separate blood genomic profile correlated with seizure freedom. These expression patterns provide new insight into previously undetected mechanisms of VPA anticonvulsant activity.

Adolescent↗

PubMed2004

Immune escape precedes breakthrough human immunodeficiency virus type 1 viremia and broadening of the cytotoxic T-lymphocyte response in an HLA-B27-positive long-term-nonprogressing child.

The emergence of cytotoxic T-lymphocyte (CTL) escape mutations in human immunodeficiency virus type 1 (HIV-1) proteins has been anecdotally associated with progression to AIDS, but it has been difficult to determine whether viral mutation is the cause or the result of increased viral replication. Here we describe a perinatally HIV-infected child who maintained a plasma viral load of <400 copies/ml for almost a decade until a nonbinding escape mutation emerged within the immunodominant CTL epitope. The child subsequently experienced a reemergence of HIV-1 viremia accompanied by a marked increase in the number of CTL epitopes targeted. This temporal pattern suggests that CD8 escape can play a causal role in the loss of immune control.

Amino Acid Sequence↗

PubMed2004

Persistent recognition of autologous virus by high-avidity CD8 T cells in chronic, progressive human immunodeficiency virus type 1 infection.

CD8 T-cell responses are thought to be crucial for control of viremia in human immunodeficiency virus (HIV) infection but ultimately fail to control viremia in most infected persons. Studies in acute infection have demonstrated strong CD8-mediated selection pressure and evolution of mutations conferring escape from recognition, but the ability of CD8 T-cell responses that persist in late-stage infection to recognize viruses present in vivo has not been determined. Therefore, we studied 24 subjects with advanced HIV disease (median viral load = 142,000 copies/ml; median CD4 count = 71/ micro l) and determined HIV-1-specific CD8 T-cell responses to all expressed viral proteins using overlapping peptides by gamma interferon Elispot assay. Chronic-stage virus was sequenced to evaluate autologous sequences within Gag epitopes, and functional avidity of detected responses was determined. In these subjects, the median number of epitopic regions targeted was 13 (range, 2 to 39) and the median cumulative magnitude of CD8 T-cell responses was 5,760 spot-forming cells/10(6) peripheral blood mononuclear cells (range, 185 to 24,700). On average six (range, one to 8) proteins were targeted. For 89% of evaluated CD8 T-cell responses, the autologous viral sequence was predicted to be well recognized by these responses and the majority of analyzed optimal epitopes were recognized with medium to high functional avidity by the contemporary CD8 T cells. Withdrawal of antigen by highly active antiretroviral therapy led to a significant decline both in breadth (P = 0.032) and magnitude (P = 0.0098) of these CD8 T-cell responses, providing further evidence that these responses had been driven by recognition of autologous virus. These results indicate that strong, broadly directed, and high-avidity gamma-interferon-positive CD8 T-cells directed at autologous virus persist in late disease stages, and the absence of mutations within viral epitopes indicates a lack of strong selection pressure mediated by these responses. These data imply functional impairment of CD8 T-cell responses in late-stage infection that may not be reflected by gamma interferon-based screening techniques.

Amino Acid Sequence↗

PubMed2004

Antigenicity of two turkey astrovirus isolates.

Astroviruses are positive-sense single-stranded RNA viruses. These viruses cause gastroenteritis in humans and in a variety of animal species, including turkey poults. Only human astroviruses are well characterized antigenically. In the current study, two turkey astrovirus isolates, TAstV1987 and TAstV2001, were antigenically compared using cross-neutralization tests in turkey embryos, as well as cross-reactivity of the two isolates by an enzyme-linked immunosorbent assay (ELISA). The antigenic relatedness values (R) were calculated using the Archetti and Horsfall formula. The R value based on the cross-neutralization tests was 0.56%, which indicates that TAstV1987 and TAstV2001 belong to different serotypes; the R value of the two viruses based on ELISA was 70.7%, which suggests these two viruses share common antigen(s).

Animals↗

PubMed2003

Neurotoxicity of polycyclic aromatic hydrocarbons and simple chemical mixtures.

Polycyclic aromatic hydrocarbons (PAHs) are a major class of environmental pollutants. These chemicals are the products of incomplete combustion and are present in every compartment of the environment. While the carcinogenic potential of these chemicals has been investigated in numerous studies, very little is known about the potential of these chemicals to produce damage to neural cells. The objective of this study was to investigate the toxicity of several model PAHs and binary mixtures of these chemicals in neural cells. Chemicals tested included benzo[a]pyrene (BaP), chrysene, anthracene, and pentachlorophenol (PCP). Four end points, including amino acid incorporation, total protein, total cell count, and viable cells (trypan dye exclusion), were measured in SY5Y human neuroblastoma cells and C6 rat glioma cells. The most sensitive measure of PAH toxicity in neural cells was amino acid incorporation into proteins. BaP was the most toxic of all PAHs tested, and anthracene failed to produce a toxic response at any concentration tested. Without metabolic activation, BaP induced a significant cytotoxic response at a concentration of 30 microM. With activation (0.25% S9), BaP induced a response at concentration levels of 3 microM and 30 microM. Minimal toxicity was observed with chrysene at the highest concentration tested, and anthracene failed to produce a toxic response at any concentration tested. With mixtures of PAHs the majority of samples induced additive responses. The minimum concentration required to induce a significant response was reduced for the mixture of chrysene and BaP when compared to BaP alone. In addition, PCP appeared to increase the inhibition of acetylcholinesterase by mipafox. The data suggest that PAHs are capable of producing damage to neural cells only at concentrations that are near their solubility limits.

Amino Acids↗

PubMed2003

Estimating the sensitivity and specificity of matching name-based with non-name-based case registries.

Because non-name-based case registries have recently been used for reporting human immunodeficiency virus infection, this study attempted to define the sensitivity, specificity and accuracy of case registry matches using non-name-based registries. The AIDS, sexually transmitted disease (STD), and tuberculosis (TB) case registries were matched using all available information to establish the standard. The registries were then matched again using five increasingly less specific criteria to compare sensitivity, specificity and accuracy. The registries were then also transformed into non-name-based codes as if they were the HIV registry and matched again. With name-based registries, sensitivities increased as the matching criteria became less exacting, while the accuracy declined slightly. Specificities remained close to 100% due to the relatively small number of matched cases. Results from matches of non-name-based registry matches were similar to those of the name-based registry matches. Non-name reporting can be used for data matching with acceptable accuracy.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Comprehensive screening reveals strong and broadly directed human immunodeficiency virus type 1-specific CD8 responses in perinatally infected children.

Advances in antiviral therapy have dramatically shifted the demographics of pediatric human immunodeficiency virus type 1 (HIV-1) infection in the developed world, and a growing proportion of perinatally HIV-1-infected children are now entering their second or even third decade of life. Although cellular immune responses to HIV are known to be weak in early infancy, the magnitude, breadth, and specificity of responses later in childhood have not been characterized in detail. We performed a comprehensive characterization of HIV-1-specific CD8 responses in 18 perinatally infected children (age range, 6 to 17 years), most of whom were on antiviral therapy, using both previously defined HIV-1 epitopes and overlapping peptides spanning all HIV-1 proteins. Multispecific responses were detected in all subjects and accounted for a median of 0.25 to 0.3% of all peripheral blood mononuclear cells that was similar to the magnitude seen in HIV-infected adults. CD8 responses were broadly directed at an average of 11 epitopes (range, 2 to 27 epitopes) and targeted nearly all HIV-1 proteins, with the highest proportion in Gag. Responses were readily detected even in those children with suppressed viremia on highly active antiretroviral therapy, although the breadth (P = 0.037) and the magnitude (P = 0.021) were significantly lower in these subjects. Each child recognized only a small minority of the HIV-1 optimal epitopes defined for his or her class I HLA alleles. Together, these data indicate that perinatally infected children who survive infancy mount a robust HIV-1-specific CD8 response that is much stronger than previously thought and is comparable in magnitude and breadth to that of adults. Moreover, this response has the potential to be broadened to target more epitopes, making these children attractive candidates for immunotherapeutic interventions.

Adolescent↗