RNA Polymerase Chain Reaction Research Articles

Gastrostomy tube insertion for improvement of adherence to highly active antiretroviral therapy in pediatric patients with human immunodeficiency virus.

Newer combination antiretroviral therapies used to treat human immunodeficiency virus (HIV)-infected individuals have resulted in dramatic delays in HIV progression, with reduction in mortality and morbidity. However, adherence to highly active antiretroviral therapy (HAART) may be problematic, particularly in HIV-infected children. Reasons for nonadherence include refusal, drug tolerability, and adverse reactions. We assess: 1) the potential benefits of gastrostomy tube (GT) for the improvement of adherence to HAART in HIV-infected children, and 2) the factors that may result in improved viral suppression after GT placement. The medical records of 17 pediatric HIV-infected patients, in whom GT was used to improve HAART adherence, were retrospectively reviewed for clinical and laboratory parameters. Each record was reviewed for the period of 1 year before and after GT insertion. The main outcome parameters were virologic (plasma HIV RNA polymerase chain reaction quantification) and immunologic (CD4 cell counts). Documentation of adherence to medications in medical records was also assessed during the study. Parental questionnaires were used to determine GT satisfaction and medication administration times. The Wilcoxon rank sum test was used to assess change in viral load (VL) and CD4 cell percentages. GT was well-tolerated with minor complications, such as local site tenderness, reported by 4 patients (23%). Before GT insertion, only 6 patients (35%) were documented as being adherent, compared with all patients after GT insertion. Ten patients (58%) had >/=2 log(10) VL decline after GT insertion (median: 3.2 log(10)), compared with 7 patients (42%) who had </=2 log(10) VL decline (median: 1.27 log(10)). Both groups of patients (responders and nonresponders) did not differ significantly in baseline parameters, such as VL, CD4 cell percentages, or previous drug therapy. However, in all 10 patients with >/=2 log(10) VL decline, therapy was changed at the time of or soon after GT insertion (median:.8 months; range: 0-6 months), compared with 7 patients with <2 log(10) VL decline who had therapy changed before GT insertion (median: 3.2 months; range: 1-8 months). Parental questionnaires reported significantly shorter medication administration times after GT insertion, with 70% of patients taking >5 minutes before GT, compared with 0% after GT. Questionnaires indicated satisfaction with GT, with perceived benefits being reduced medication administration time and improved behavior surrounding taking medications. GT is well-tolerated in pediatric HIV-infected patients and should be considered for selected patients to overcome difficulties with medication administration and to improve adherence. For maximal virologic response, combination therapy should be changed at the time of GT insertion.

Developmental expression of amphiphysin in the retinotectal system of the chick: from mRNA to protein.

The role of amphiphysin in clathrin-mediated endocytosis of synaptic vesicles is well established. However, it is still uncertain if the protein is also involved in developmental mechanisms, e.g. axon outgrowth and synapse formation. To investigate the developmental changes in the expression of amphiphysin we used the retinotectal system of the chick, a highly ordered and easily accessible primary neuronal pathway. Reverse transcription polymerase chain reaction (RT-PCR) of total RNA from chick retina and tectum revealed first transcripts for amphiphysin, dynamin and synaptotagmin at embryonic day 5 (E5) for both regions. Surprisingly, Western blots of the retina revealed an increase of protein expression for amphiphysin only after E11 in the retina and the tectum. Immunofluorescence for amphiphysin was not detectable before E10 in the developing chick retina, while other presynaptic proteins like synaptotagmin showed already intense signals in the inner and outer plexiform layers. Subsequently, amphiphysin immunoreactivity follows the expression of synaptotagmin and synaptic vesicle protein 2 (SV2) as seen in the retina and the tectum, and exhibits the same staining as the other proteins in the mature chick brain. Ultrastructural data revealed for the first time that amphiphysin is not only limited to conventional synapses but is also abundant in retinal ribbon terminals. Taken together our data reveal that: (i) there is a developmental delay between mRNA transcription and protein expression for key proteins involved in endocytosis; (ii) amphiphysin gets upregulated after synapse formation; and (iii) amphiphysin is present in the synaptic vesicle cycle in retinal ribbon synapses.

Heparin interference with reverse transcriptase polymerase chain reaction of RNA extracted from lungs after ischemia-reperfusion.

The reverse transcriptase polymerase chain reaction (RT-PCR) is a rapid and sensitive method for detecting gene expression. However, when we used this technique to study gene expression of cytokines in ischemic and ex-vivo-reperfused rat lungs as a model for transplantation, significant inhibition of RT-PCR reaction was observed. To optimize RT-PCR conditions, RNA was extracted from rat lungs after flushing, preservation, and reperfusion. RNA was further purified and PCR conditions were modified with various strategies. We found that heparinase I pretreatment completely overcame the inhibitory effects of RT-PCR using RNA extracted from lung tissues after ischemia-reperfusion. With this treatment, a dramatic increase in tumor necrosis factor-a (TNF-a) mRNA was revealed from lung tissues after ischemia-reperfusion. This result suggests that residual heparin in lung tissue interferes with RT-PCR. Because heparinization is routinely used during clinical and experimental organ transplantation, we recommend the treatment of RNA samples with heparinase prior to RT-PCR.

Human tumor growth is inhibited by a vaccinia virus carrying the E2 gene of bovine papillomavirus.

Papillomavirus is the etiologic agent associated with cervical carcinoma. The papilloma E2 protein is able to regulate negatively the expression of E6 and E7 papilloma oncoproteins. Therefore, a new, highly attenuated vaccinia virus known as modified vaccinia virus Ankara (MVA), which carries the papillomavirus E2 gene, was used for the treatment of tumors associated with human papillomavirus. Analysis of expression of the E2 gene from the recombinant vaccinia virus was performed by reverse transcription-polymerase chain reaction of RNA isolated from infected cells. Detection of the E2 protein was done by immunoprecipitation from proteins labeled with [(35)S]-methionine, isolated from infected cells. The therapeutic effect of the MVA E2 recombinant virus over human tumors was tested in nude mice bearing tumors generated by inoculation of HeLa cells. Series of 10 nude mice with tumors of different sizes were injected with MVA, MVA E2, or phosphate-buffered saline. Tumor size was monitored every week to assess growth. The MVA E2 recombinant virus efficiently expressed the E2 protein in BS-C-1 cells. This protein was able to repress, in vivo, the papillomavirus P105 promoter, which controls the expression of the E6 and E7 oncoproteins. In nude mice the MVA E2 virus reduced tumor growth very efficiently. In contrast, tumors continued to grow in mice treated with MVA or PBS. The life expectancy of MVA E2-treated mice was also increased three- to fourfold compared with that of animals that received MVA or PBS. The growth of human tumors was efficiently inhibited by the MVA E2 recombinant vaccinia virus. The absence of side effects in treated animals suggested that the MVA E2 virus is a safe biologic agent that could in the future be used in humans for the treatment of cervical carcinoma.

Early expression of angiogenesis factors in acute myocardial ischemia and infarction.

When the myocardium is deprived of blood, a process of ischemia, infarction, and myocardial remodeling is initiated. Hypoxia-inducible factor 1 (HIF-1) is a transcriptional activator of vascular endothelial growth factor (VEGF) and is critical for initiating early cellular responses to hypoxia. We investigated the temporal and spatial patterns of expression of the alpha subunit of HIF-1 (HIF-1alpha) and VEGF in specimens of human heart tissue to elucidate the early molecular responses to myocardial hypoxia. Ventricular-biopsy specimens from 37 patients undergoing coronary bypass surgery were collected. The specimens were examined by microscopy for evidence of ischemia, evolving infarction, or a normal histologic appearance. The specimens were also analyzed with the reverse-transcriptase polymerase chain reaction for HIF-1alpha and VEGF messenger RNA (mRNA) expression and by immunohistochemical analysis for the location of the HIF-1alpha and VEGF proteins. HIF-1alpha mRNA was detected in myocardial specimens with pathological evidence of acute ischemia (onset, <48 hours before surgery) or early infarction (onset, <24 hours before surgery). In contrast, VEGF transcripts were seen in specimens with evidence of acute ischemia or evolving infarction (onset, 24 to 120 hours before surgery). Patients with normal ventricles or evidence of infarction in the distant past had no detectable levels of either VEGF mRNA or HIF-1alpha mRNA. HIF-1alpha immunoreactivity was detected in the nuclei of myocytes and endothelial cells, whereas VEGF immunoreactivity was found in the cytoplasm of endothelial cells lining capillaries and arterioles. An increase in the level of HIF-1alpha is an early response to myocardial ischemia or infarction. This response defines, at a molecular level, one of the first adaptations of human myocardium to a deprivation of blood. HIF-1alpha is a useful temporal marker of acutely jeopardized myocardium.

Heparin interference with reverse transcriptase polymerase chain reaction of RNA extracted from lungs after ischemia-reperfusion

Heparin interference with reverse transcriptase polymerase chain reaction of RNA extracted from lungs after ischemia-reperfusion

Cloning, sequencing, and expression of the hepatitis E virus (HEV) nonstructural open reading frame 1 (ORF1)This work was performed at the Department of Pathology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India

Hepatitis E virus (HEV) causes enterically transmitted epidemic and sporadic viral hepatitis affecting millions of people in the developing world. Different geographical isolates of HEV show a high degree of homology at the nucleotide and amino acid levels. The ∼7.2 kb RNA genome has three open reading frames of which ORF1 is predicted to code for the viral nonstructural polyprotein. The expression, processing and properties of the nonstructural ORF1 polyprotein have not been reported so far. In this study, the complete HEV ORF1 was reconstructed from overlapping fragments amplified by polymerase chain reaction (PCR) of total RNA isolated from the bile fluid of a rhesus monkey experimentally infected with HEV isolate from an epidemic. The complete assembled ORF1 was sequenced using HEV specific primers. The ORF1 polyprotein was expressed in E. coli, in a cell free translation system and in HepG2 cells, and was characterized by western blotting and immunoprecipitation using acute phase patient serum as well as polyclonal antibodies raised against defined parts of the ORF1 polyprotein. The nonstructural polyprotein of HEV was expressed as a 186 kDa protein. No processing was observed into discrete units, either in-vitro based on a kinetic analysis, or in HepG2 cells based on immunoprecipitation. J. Med. Virol. 60:275–283, 2000. © 2000 Wiley-Liss, Inc.

Differentiation of Poaceae Potyviruses by Reverse Transcription‐Polymerase Chain Reaction and Restriction Analysis

Four potyviruses have been reported to infect Poaceae: maize dwarf mosaic virus (MDMV), sugarcane mosaic virus (SCMV), johnsongrass mosaic virus (JGMV) and sorghum mosaic virus (SrMV). A procedure was developed to assess the potential presence of potyviruses in a Poaceae‐infected sample, and then to determine which potyvirus species (one or more) were present. The first step was potyvirus‐group specific and following total RNA extraction, reverse transcription and polymerase chain reaction, it yielded a 327 nucleotide fragment spanning MVWCIEN to QMKAAA conserved motifs in the core of the capside gene. Enzymatic restriction of this fragment with the two endonucleases AluI and DdeI gave virus‐specific patterns. This method was shown to be efficient for dealing with well‐characterized strains and field collected isolates and useful for determining co‐infections and detecting a new potyvirus infecting maize.

CD4 count/viral load in HIV.

CD4 count/viral load in HIV.

Porcine reproductive and respiratory syndrome virus (PRRSV): kinetics of infection in lymphatic organs and lung.

SummaryPigs were infected by the oronasal route with European isolates of the porcine reproductive and respiratory syndrome virus (PRRSV; I10 and Cobbelsdorf). The kinetics of infection in lymphatic organs and the lung were analysed by immunofluorescence detection of virus antigen, re‐isolation of the virus and reverse transcription‐polymerase chain reaction (RT‐PCR) for PRRSV‐specific RNA. The kinetics of PRRSV infection proceeded in three phases, irrespective of the varying infestation of lymphatic organs within the first days post‐infection (p.i.). First, an early acute infection of lymphatic organs developed within the first week and was characterized by a high number of antigen‐positive macrophages. Second, a delayed acute infection of the lung was observed, which was most pronounced during the second and third week p.i. when a high number of infected alveolar macrophages was observed. The acute infection of lymphatic organs had resolved at this time. Infected cells in the lung were predominantly located in pneumonic lesions. Third, a persistent infection was demonstrated by RT‐PCR and immunohistology when the experiments were terminated at day 49 p.i. The virus persisted in lymphatic organs, especially in the tonsils, and in the lung. At this stage, indications for a re‐occurrence of acute infection were observed in restricted areas of the lung.

Characterization of an ascidian DEAD-box gene, Ci-DEAD1: specific expression in the germ cells and its mRNA localization in the posterior-most blastomeres in early embryos.

We isolated DEAD-box genes from three ascidian species (Ciona intestinalis, Ciona savignyi, and Halocynthia roretzi) by polymerase chain reaction methods. We obtained two types from each of C. intestinalis and C. savignyi, and four types from H. roretzi. The first type (DEAD1) belonged to the vasa subfamily, the second type (DEAD2) to the PL10 subfamily, the third type (DEAD3) to the p68 subfamily, and the forth type (DEAD4) did not belong to any of the subfamilies. We further analyzed in detail the expression pattern of C. intestinalis vasa-type gene (Ci-DEAD1) by in situ hybridization. In sections of the ovary and testis, the Ci-DEAD1-specific probe reacted intensely to small germ cells, oogonium, and/or oocyte and spermatogonium and/or spermatocyte, respectively. In whole-mount specimens of juveniles this probe specifically reacted to the primordial germ cells in the gonad rudiment. These gonad-specific expressions were confirmed by reverse transcriptase polymerase chain reaction of RNA from various tissues. The transcript was present in unfertilized eggs and in the central cytoplasm of blastomeres until the two-cell stage. During the second cleavage a part of the transcripts moved to the posterior region of embryos and, during early embryogenesis, was localized in the posterior-most blastomeres. In the tailbud, one or two hybridization signals were detected in the caudal endodermal strand. Based on these observations, we propose precursors of primordial germ cells in ascidians.

45-year follow-up of hepatitis C virus infection in healthy young adults.

The sequelae during the first two decades after acute hepatitis C virus (HCV) infection have been well studied, but the outcome thereafter is unknown. To conduct an extended study of the natural history of HCV infection by using archived serum specimens originally collected between 1948 and 1954. Retrospective cohort study. A university, a Veterans Affairs medical center, and a medical follow-up agency that had access to the serum specimens and accompanying demographic and medical records. 8568 military recruits who were evaluated for group A streptococcal infection and acute rheumatic fever between 1948 and 1954. Blood samples were taken from the recruits and, after testing, were stored frozen for almost 45 years. The presence of antibodies to HCV was determined by enzyme-linked immunoassay, supplementary recombinant immunoblot assay, and polymerase chain reaction for HCV RNA. Morbidity and mortality were also assessed. Of 8568 persons, 17 (0.2%) had positive results on enzyme-linked immunosorbent assay and recombinant immunoblot assay. The rate was 1.8% among the African-American persons and 0.1% among the white persons in the total sample (relative risk, 25.9 [95% CI, 8.4 to 80.0]). During the 45-year follow-up, liver disease occurred in 2 of the 17 HCV-positive persons (11.8%) and 205 of the 8551 HCV-negative persons (2.4%) (ethnicity-adjusted relative risk, 3.56 [CI, 0.94 to 13.52]). Seven of the 17 HCV-positive persons (41 %) and 2226 of the 8551 HCV-negative persons (26%) had died by December 1996 (ethnicity-adjusted relative risk, 1.48 [CI, 0.8 to 2.6]). Of persons who were HCV-positive, 1 (5.9%) died of liver disease 42 years after the original phlebotomy, 5 (29%) died of non-liver-related disease a median of 37 years after the original phlebotomy, and 1 (5.9%) died of unknown causes. One hundred nineteen HCV-negative persons (1.4%) died of liver disease. The rate of HCV infection from 1948 to 1954 among a sample of military recruits parallels that among present-day military recruits and volunteer blood donors. During 45 years of follow-up, HCV-positive persons had low liver-related morbidity and mortality rates. This suggests that healthy HCV-positive persons may be at less risk for progressive liver disease than is currently thought.

Cloning, sequencing, and expression of the hepatitis E virus (HEV) nonstructural open reading frame 1 (ORF1)

Hepatitis E virus (HEV) causes enterically transmitted epidemic and sporadic viral hepatitis affecting millions of people in the developing world. Different geographical isolates of HEV show a high degree of homology at the nucleotide and amino acid levels. The approximately 7.2 kb RNA genome has three open reading frames of which ORF1 is predicted to code for the viral nonstructural polyprotein. The expression, processing and properties of the nonstructural ORF1 polyprotein have not been reported so far. In this study, the complete HEV ORF1 was reconstructed from overlapping fragments amplified by polymerase chain reaction (PCR) of total RNA isolated from the bile fluid of a rhesus monkey experimentally infected with HEV isolate from an epidemic. The complete assembled ORF1 was sequenced using HEV specific primers. The ORF1 polyprotein was expressed in E. coli, in a cell free translation system and in HepG2 cells, and was characterized by western blotting and immunoprecipitation using acute phase patient serum as well as polyclonal antibodies raised against defined parts of the ORF1 polyprotein. The nonstructural polyprotein of HEV was expressed as a 186 kDa protein. No processing was observed into discrete units, either in-vitro based on a kinetic analysis, or in HepG2 cells based on immunoprecipitation.

Expression of prophenoloxidase mRNA during silkworm hemocyte development.

Two clones encoding different prophenoloxidase isoforms were amplified by polymerase chain reaction of RNA from the hemocytes of an experimental strain of Bombyx mori. The nucleotide sequences of the clones and the deduced amino acid sequences were confirmed to be nearly identical to those of the orthologous clones previously obtained from a commercial race of B. mori. Northern blot hybridization using these clones as probes demonstrated that the prophenoloxidase mRNA in the hemocytes is expressed in a stage-specific manner during the final larval instar and pupal stage, showing a peak one day before pupation in males and on the day of pupation in females. A sexual difference was also observed when the content of prophenoloxidase protein in the hemolymph (including hemocytes) was measured by an enzyme-linked immunosorbent assay.

In vivo analysis of cancerous gene expression by RNA-polymerase chain reaction.

An easy and routine procedure to amplify messenger RNA (mRNA) libraries from a few tissue cells can provide molecular gene expression profiles at high resolution. A novel PCR-like method, the RNA-PCR, was developed to generate high quality and quantity mRNAs from as few as 20 cells (2 pg mRNAs). The principle relies upon the cycling steps of promoter-linked double-stranded cDNA synthesis and promoter-driven transcription to amplify mRNAs up to 250-fold/cycle with good representation of high and low copy mRNAs. The amplified mRNA libraries were shown to possess high fidelity, purity, specificity and reproducibility for in vivo analyses of cancerous gene expression in human prostate cancers.

Increase in hepatitis C virus load in hemophiliacs during treatment with highly active antiretroviral therapy.

The effect of highly active antiretroviral therapy (HAART) on liver function and viral load of hepatitis C virus (HCV) was studied in 21 hemophilic men coinfected with HCV and human immunodeficiency virus (HIV). HCV RNA polymerase chain reaction was measured by branched DNA Quantiplex assay on frozen plasma samples obtained at baseline and at 24, 48, and 96 weeks after initiation of HAART. HCV RNA increased at 48 and 96 weeks after initiation of HAART therapy (198x105 Eq/mL [P=.03] and 227x105 Eq/mL [P<.0001], respectively, compared with baseline [141x105 Eq/mL]). This increase was associated with an increase in CD4 cell count and reduction in HIV viral load but no change in hepatic transaminases. With discontinuation of HAART, HCV RNA decreased as HIV RNA rebounded. Further study is required to clarify the histopathologic significance of this finding.

Selective expression of RT6 superfamily in human bronchial epithelial cells.

RT6 proteins are glycosylphosphatidylinositol (GPI)-linked alloantigens that are localized to cytotoxic T lymphocytes and that have nicotinamide adenine dinucleotide glycohydrolase and adenosine diphosphate (ADP)-ribosyltransferase activities. In view of the importance of GPI-linked surface proteins in mediating interactions of cells with their milieu, and the varied functions of airway cells in inflammation, we undertook the present study to determine whether human homologues of the RT6 superfamily of ADP-ribosyltransferases (ART) are expressed in pulmonary epithelial cells. We hypothesized that these surface proteins or related family members may be present in cells that interact with inflammatory cells, and that they may thereby be involved in intercellular signaling. Using in situ analysis and Northern blot analysis, we identified ART1 messenger RNA (mRNA) in airway epithelial cells. As expected for GPI-anchored proteins, the localization of ART1 at the apical surface of ciliated epithelial cells was demonstrated by staining with polyclonal anti-ART1 antibody, and was confirmed by loss of this immunoreactivity after treatment with phosphatidylinositol-specific phospholipase C (PI-PLC), which selectively cleaves GPI anchors and releases proteins from the plasma membrane. Using in situ hybridization with specific ART3 and ART4 oligonucleotides, we also identified two additional members of the RT6 superfamily in epithelial cells. In accord with these findings, we identified ART3 and ART4 mRNAs through reverse transcription- polymerase chain reaction of polyadenine-positive RNA from human trachea. Interestingly, these proteins appeared to be preferentially localized to the airway epithelium. The localized expression of these members of the RT6 superfamily in human pulmonary epithelial cells may reflect a role for them in cell-cell signaling during immune responses within the airway.

The human immunoglobulin variable lambda locus IGLV9 gene is a monomorphic marker in the urban Brazilian population

The physical map of the human immunoglobulin variable lambda locus (IGLV) located on chromosome 22q11.1-q11.2 shows the existence of 52 functional V-lambda genes distributed among three V-clusters. The IGLV9S1 gene, located in the V–B cluster, is a sequence tagged site and is a useful marker for restriction fragment length polymorphism (RFLP) population studies. The V-lambda genes are associated in the genome with EcoRI fragments detectable in Southern blots of genomic DNA samples. We have analysed DNA samples of an urban Brazilian population by Southern- EcoRI-RFLP using an IGLV9 gene segment. Among 75 unrelated individuals analysed, we detected a single 6.0 kb EcoRI fragment containing the IGLV9 gene at 100% frequency. Reverse transcription followed by polymerase chain reaction (RT-PCR) of peripheral blood leukocyte total RNA from unrelated individuals showed that IGLV9S1 is a functional gene contributing to the B lymphocyte repertoire. These data represent evidence for monomorphism of the IGVL9S1 gene in this urban population. We demonstrate that IGLV9S1 is a functional single copy gene and is an important marker in the IGLV locus.

Molecular analysis of malignant triton tumors

Triton tumors are rare variants of malignant peripheral nerve sheath tumor (MPNST) with muscle differentiation, often seen in patients with neurofibromatosis 1 (NF1). Individuals affected with NF1 harbor mutations in the NF1 tumor suppressor gene and develop neurofibromas and MPNSTs. The NF1 gene is expressed in Schwann cells and its expression is lost in schwannian neoplasms, suggesting a role in malignant development. Separately, there is evidence that p53 suppressor gene mutations are involved in MPNSTs. To determine the role of the NF1 and p53 genes in the development of the malignant Triton tumor we examined 2 such tumors, 1 from a 3-year-old boy without clinical manifestations of NF1 and another from a 24-year-old man with NF1. Histological analysis of these tumors showed both neural and muscle differentiation with S-100 and desmin immunoreactivity, respectively. Reverse transcribed RNA polymerase chain reaction (RT-PCR) of NF1 mRNA showed NF1 expression in the sporadic tumor. Strong nuclear immunoreactivity for p53 was observed throughout the malignant population in both tumors. This was confirmed by loss of heterozygosity for p53 in the non-NF1 patient, suggesting that p53 is involved in both hereditary and sporadic Triton tumors. The finding of preserved NF1 gene expression in the non-NF1-related Triton tumor suggests that different genetic events predispose to the development of this rare neoplasm in sporadic cases.

Ritonavir combination therapy restores intestinal function in children with advanced HIV disease.

To investigate the intestinal absorptive processes in children with HIV infection before and after treatment with combination therapy that includes ritonavir. To test the hypothesis that combination therapy improves intestinal function. Intestinal function tests were performed in 10 children with advanced HIV disease at the enrollment and after 3 and 6 months of therapy with ritonavir combined with two HIV reverse transcriptase inhibitors. HIV viral load and CD4 cell counts were also determined; body weight was monitored. The D-xylose absorption test, the steatocrit and the determination of fecal alpha1-antitrypsin concentration were used to evaluate carbohydrate and fat absorption, as well as fecal protein loss. Serum iron levels were measured to indirectly evaluate iron absorption. HIV-1 RNA-polymerase chain reaction (PCR) and immunofluorescence imaging were used to evaluate virologic and immunologic responses. In all, 9 children had carbohydrate malabsorption, 3 steatorrhea, 2 protein loss, and 7 iron deficiency. Most tests produced normal results after 3 months of therapy, and all abnormalities were abolished 6 months after institution of combination therapy. Mean results of each of four absorption tests were significantly changed on combination therapy. Viral load was progressively reduced and CD4 count was increased, with an inverse relationship. An evident shift of body weight pattern toward catch-up growth was observed in all children. Ritonavir combination therapy results in prompt and sustained restoration of intestinal function, which is associated with reduction in viral load, increase in CD4 counts, and gain in body weight.