Enteric pathogens associated with gastrointestinal dysfunction in children with HIV infection

Infants and young children with HIV infection commonly suffer from gastrointestinal manifestations of their disease. Many HIV infected children have evidence of persistent diarrhoea, malabsorption, malnutrition or growth failure. The aetiology and pathogenesis of gastrointestinal dysfunction in HIV infected children have not been well defined. We performed immunocytochemical analyses on intestinal tissue from 19 HIV-infected children with gastrointestinal dysfunction or growth failure. None of these 19 children had microbial pathogens identified in faecal samples using standard microbiological methods. Intestinal tissues were obtained from the children by biopsy and were examined for antigens from Pneumocystis carinii, cytomegalovirus (CMV) and herpes simplex virus (HSV) using the avidin-biotin-complex immunohistochemical technique and monoclonal or monospecific antibodies. We detected at least one of these pathogens in samples from eight (42%) of 19 HIV infected children. P. carinii was the most prevalent pathogen, found in five of the eight HIV infected children. All of the children with intestinal pneumocystis infection were receiving prophylaxis directed at the prevention of pulmonary disease with this organism and none of them were undergoing active pulmonary infection. We also identified CMV antigens in intestinal tissues from four children and HSV antigens in intestinal tissues from one child. Two children were infected with more than one pathogen. On the other hand, none of these pathogens were found in the tissues obtained from 10 HIV-uninfected patients who had intestinal tissues obtained for chronic non-infectious diarrheal and inflammatory diseases (P < 0.01, Fisher's exact test). Our findings indicate that some children with HIV infection and gastrointestinal dysfunction may be infected with opportunistic pathogens despite negative analyses employing standard microbiological methods. Our study also indicates that HIV infected children can undergo intestinal infection with P. carinii despite the administration of standard immunoprophylactic regimens directed at the prevention of infection with this organism.

Longitudinal growth during the first 2 years of life in children born to HIV-infected mothers in Malawi, Africa

To evaluate the longitudinal growth patterns of infants born to HIV-infected and uninfected mothers in Malawi, Africa, 92 HIV-infected infants, 270 uninfected infants born to HIV-infected mothers, and 686 infants born to uninfected mothers between birth and 24 months of life were studied. Weight and length were evaluated longitudinally utilizing generalized estimating equations. HIV-infected children were compared with uninfected children born to HIV-infected and uninfected mothers, and to United States National Center for Health Statistics (NCHS) growth standards. Median weight and length-for-age of seronegative infants born to either seronegative or seropositive mothers approximated the NCHS median from birth to approximately 4 months of age. Median weight and length of HIV-infected infants deviated from the NCHS median at an earlier age, and the deviation was more pronounced than was observed for uninfected infants. Mean growth curves constructed by generalized estimating equations indicated that HIV-infected and uninfected infants born to HIV-infected mothers weighed less and were smaller than infants born to HIV-uninfected mothers initially. Mean weight and length of uninfected infants attained the median of infants born to uninfected mothers by 24 months of age, while HIV-infected infants remained below this median. The difference in mean weight-for-age for HIV-infected and uninfected infants born to HIV-infected mothers was statistically significant from birth. The difference in mean length-for-age was statistically significant after 5 months of age. Thus, although infants born to HIV-infected mothers were smaller and weighed less initially, uninfected infants caught up, while HIV-infected infants remained below the median, and the deficit in weight occurred earlier in life than the deficit in length.

Evaluation of the effects of disinfectants on rotavirus RNA and infectivity by the polymerase chain reaction and cell-culture methods

Rotaviruses have been linked to outbreaks of acute gastroenteritis of children in day-care centres and hospital paediatric wards. There is, therefore, the need for monitoring effective decontamination of such environments. We have evaluated the effects of seven different methods of disinfection/inactivation (four chemical and three physical) on rotavirus using the PCR and cell-culture methods. We observed that 6% H2O2, 2500 ppm chlorine, an ethano-phenolic disinfectant, u.v. irradiation and heat completely destroyed the infectivity of rotavirus as well as RNA amplifiable by PCR. On the other hand, treatment with 80% ethanol resulted in the loss of infectivity despite the fact that RNA was still amplifiable. Rotavirus subjected to drying over a 24 h period still retained amplifiable RNA but infectivity was reduced by 100-fold when compared to the control. This study demonstrated an agreement between PCR and cell-culture monitoring systems, however, PCR is a more rapid and sensitive assay.

The 5'-untranslated region sequence of a potential new genotype of bovine viral diarrhea virus

The 5' untranslated region (UTR) of several bovine viral diarrhea virus (BVDV) isolates from the severe Quebec outbreak was amplified by polymerase chain reaction (PCR) and sequenced. Sequences revealed the loss, for the BVDV type II isolates, of an internal PstI restriction site, which is present in all known BVDV type 1 5' UTR sequences. A single restriction enzyme digestion (PstI) of an aliquot of PCR product allowed us to differentiate BVDV type I and BVDV type II.

Longitudinal assessment of growth in children born to mothers with human immunodeficiency virus infection

OBJECTIVES

To describe and to evaluate the longitudinal growth of children born to mothers with human immunodeficiency virus (HIV) infection.

DESIGN

Measurements of weight, length (measured in infants in a recumbent position) and height (measured in older children in an upright position), and head circumference were documented and evaluated longitudinally using generalized estimating equations in a group of children born to HIV-infected mothers. Children infected with HIV were compared with uninfected children and with National Center for Health Statistics standards.

SETTING

Primary care clinic in an urban hospital devoted to the medical care of children born to HIV-infected mothers.

PATIENTS

One hundred nine children born to HIV-infected mothers, 59 HIV-infected and 50 uninfected, between birth and 70 months of age.

RESULTS

The mean birth weights of both groups were below the 50th percentile. While the mean weight-for-age curve of uninfected children attained the 50th percentile by age 24 months, the mean birth weight-for-age curve of HIV-infected children remained below the 50th percentile. Weight gain became significantly different between the two groups by age 36 months. The mean birth length-for-age curves of HIV-infected and uninfected children was also below the 50th percentile. The mean height-for-age curve of uninfected children attained the 50th percentile by age 40 months, while that of HIV-infected children remained well below the 50th percentile. Linear growth between HIV-infected and uninfected children diverged earlier than weight, becoming significantly different by age 15 months.

CONCLUSIONS

Although children born to HIV-infected mothers are born with weight and length below the 50th percentile, uninfected children catch up, while HIV-infected children remain below the 50th percentile and experience an earlier and more pronounced decrease in linear growth (height-for-age) than in weight-for-age.

Human milk glycosaminoglycans inhibit HIV glycoprotein gp120 binding to its host cell CD4 receptor

The binding of the HIV envelope glycoprotein, gp120, to its host cell receptor, CD4, is inhibited in a solid phase assay by a glycosaminoglycan of human milk; this binding is the essential first step in HIV infectivity. The human milk glycosaminoglycans were identified in this study. Pooled, fractionated human milk contained dermatan sulfate, heparin, heparan sulfate, and chondroitin sulfate. The ability of this glycosaminoglycan fraction to inhibit binding was unaffected by digestion with lytic enzymes specific for heparin, heparan sulfate and dermatan sulfate, but was lost when the milk fraction was treated with lytic enzymes specific for chondroitin sulfate. Furthermore, a purified milk fraction with high specific inhibitory activity contained chondroitin sulfate but not other glycosaminoglycans. This indicates that the ability of human milk to inhibit gp120 binding to CD4 may be attributed to chondroitin sulfate or to a chondroitin sulfate-like moiety rather than to other components of human milk. We speculate that this human milk glycosaminoglycan could limit the rate of postnatal vertical transmission of HIV in breast-fed infants of HIV-infected mothers.

Polymerase chain reaction (PCR) search for viral nucleic acid sequences in schizophrenia

BACKGROUND

Previous studies looking for evidence of viral infection in schizophrenics have yielded conflicting results. We searched for viral nucleic acids to test the hypothesis of the viral aetiology of schizophrenia.

METHOD

We used the polymerase chain reaction (PCR) to search for cytomegalovirus (CMV), human immunodeficiency virus (HIV), influenza A, Borna disease virus (BDV), and bovine viral diarrhoea virus (BVDV) in: hippocampus from three schizophrenic and three non-schizophrenic subjects; cerebrospinal fluid (CSF) from 48 schizophrenic patients; CSF and peripheral blood mononuclear cells (PBMC) from nine sets of identical twins discordant for schizophrenia; and SK-N-SHEP cells co-cultured with schizophrenic and non-schizophrenic brain homogenates. All patients met DSM-III-R criteria.

RESULTS

Virus-specific nucleic acids were not found in any of the samples tested.

CONCLUSIONS

The absence of viral nucleic acids in the samples tested suggest that, in these patients, schizophrenia is not associated with a persistent or latent infection due to these viruses.

Viruses, schizophrenia, and bipolar disorder

The hypothesis that viruses or other infectious agents may cause schizophrenia or bipolar disorder dates to the 19th century but has recently been revived. It could explain many clinical, genetic, and epidemiologic aspects of these diseases, including the winter-spring birth seasonality, regional differences, urban birth, household crowding, having an older sibling, and prenatal exposure to influenza as risk factors. It could also explain observed immunological changes such as abnormalities of lymphocytes, proteins, autoantibodies, and cytokines. However, direct studies of viral infections in individuals with these psychiatric diseases have been predominantly negative. Most studies have examined antibodies in blood or cerebrospinal fluid, and relatively few studies have been done on viral antigens, genomes, cytopathic effect on cell culture, and animal transmission experiments. Viral research on schizophrenia and bipolar disorder is thus comparable to viral research on multiple sclerosis and Parkinson's disease: an attractive hypothesis with scattered interesting findings but no clear proof. The application of molecular biological techniques may allow the identification of novel infectious agents and the associations of these novel agents with serious mental diseases.

Could schizophrenia be a viral zoonosis transmitted from house cats?

Studies have suggested that some cases of schizophrenia may be caused by viruses. We hypothesize that such cases may be cases of viral zoonosis transmitted primarily from house cats. Epidemiological aspects of schizophrenia and a case-control questionnaire support this hypothesis.

Feeding of Bifidobacterium bifidum and Streptococcus thermophilus to infants in hospital for prevention of diarrhoea and shedding of rotavirus

Acute diarrhoea is a serious cause of infant morbidity and mortality, and the development of preventive measures remains an important goal. Bifidobacteria (which constitute the predominant intestinal flora of breastfed infants), as well as other lactic-acid-producing organisms such as Streptococcus thermophilus, are thought to have a protective effect against acute diarrhoeal disease. However, their efficacy has not been assessed in controlled trials. In a double-blind, placebo-controlled trial, infants aged 5-24 months who were admitted to a chronic medical care hospital were randomised to receive a standard infant formula or the same formula supplemented with Bifidobacterium bifidum and S thermophilus. Patients were evaluated daily for occurrence of diarrhoea, and faecal samples, obtained weekly, were analysed for rotavirus antigen by enzyme immunoassay. Faecal samples were also obtained during an episode of diarrhoea for virological and bacteriological analyses. 55 subjects were evaluated for a total of 4447 patient-days during 17 months. 8 (31%) of the 26 patients who received the control formula and 2 (7%) of 29 who received the supplemented formula developed diarrhoea during the course of the study (p = 0.035, Fisher's exact test, two-tailed). 10 (39%) of the subjects who received the control formula and 3 (10%) of those who received the supplemented formula shed rotavirus at some time during the study (p = 0.025). The supplementation of infant formula with B bifidum and S thermophilus can reduce the incidence of acute diarrhoea and rotavirus shedding in infants admitted to hospital.

Effect of enteral tube feeding on growth of children with symptomatic human immunodeficiency virus infection

Malnutrition and growth failure are frequent clinical consequences of human immunodeficiency virus (HIV) infection in children. Tube feeding is a means by which to increase the enteral intake of nutrients. We examined the effect of tube feeding in 18 children, median age 6 months (range, 3-159). Tube feedings were initiated due to growth failure in all, which was also associated with dysfunctional swallowing or aspiration in seven children and gastroesophageal reflux in two. Tube feedings were infused via nasogastric tube (n = 4) or gastrostomy tube (n = 14) and were continued for a median of 8.5 months (range, 2-24). Stoma complications developed in three children with gastrostomy tubes; these were the only tube-related side effect. Tube feedings were discontinued due to noncompliance (n = 3), gastrostomy leakage (n = 2), intolerance (n = 2), and death (n = 3). Anthropometric changes were evaluated comparing mean standard deviation scores (Z) before and after tube feeding. Tube feeding resulted in significantly increased weight for age (Z, -2.13 +/- 0.7 vs. -1.46 +/- 1.4; p = 0.04), weight for height (Z, -1.07 +/- 1.0 vs. -0.13 +/- 1.0; p = 0.004), and arm fat area (Z, -1.75 +/- 1.3 vs. -0.62 +/- 1.2; p = 0.01). However, tube feeding did not result in significant changes in height for age (Z, -1.93 +/- 0.8 vs. -1.74 +/- 1.6) or arm muscle area (Z, -1.24 +/- 0.9 vs. -0.57 +/- 1.2). Tube feedings effectively increased the weight of HIV-infected children in this study, but they were not sufficient to correct linear growth deficits.

Intestinal mucins inhibit rotavirus replication in an oligosaccharide-dependent manner

Rotaviruses are important causes of infant morbidity and mortality worldwide. It has been previously shown that mucinous glycoproteins can inhibit rotavirus replication. However, the structure-function relationships of this inhibition have not been completely elucidated. Mucins were purified from epithelial scrapings of rat and human intestine by CsCl density-gradient ultracentrifugation and tested for the inhibition of rotavirus replication in MA-104 cells. Native human and rat intestinal mucins inhibited the replication of human and animal rotaviruses at low concentrations. Antiviral activity was most prominent in the densely glycosylated part of the rat and human mucins. Activity was retained after thiol reduction and alkylation, chloroform methanol partition, and partial removal of oligosaccharides. However, total deglycosylation of the mucins destroyed antiviral activity. Intestinal mucins from humans and other animals are potent inhibitors of rotavirus replication, and this inhibition is dependent on specific mucin-viral interactions.

Use of PCR-enzyme immunoassay for identification of influenza A virus matrix RNA in clinical samples negative for cultivable virus

Influenza A virus infections are a major cause of morbidity and mortality worldwide. Standard diagnostic methods either are not efficient in identifying infected individuals in a timely manner or lack sensitivity. We developed a PCR-enzyme immunoassay (PCR-EIA) for the detection of influenza A virus RNA in respiratory secretions. A reverse transcription PCR was performed with oligonucleotide primers directed at a highly conserved area of the influenza A matrix gene. Amplified DNA was identified by hybridization in solution to a nested biotinylated RNA probe and quantitated in an EIA. PCR-EIA detected small quantities of RNA from the three prevalent subtypes of human influenza A virus. Influenza B and C, parainfluenza, measles, mumps, and respiratory syncytial viruses tested negative. The potential efficiency of PCR-EIA for use in clinical diagnosis was determined by testing 90 nasal wash specimens obtained daily over a 10-day period from nine human volunteers infected with influenza A virus. Thirty-seven of the postinfection samples had detectable influenza A virus RNA by PCR-EIA, whereas only 26 postinfection samples were positive by culture. PCR-EIA was particularly efficient for the identification of influenza A virus in samples obtained more than 4 days after infection. Seventeen of 45 such samples were positive, whereas virus was cultivated from 4 samples (P < 0.00005). All preinfection samples from volunteers subsequently infected with influenza A virus were negative by PCR-EIA, as were samples from a volunteer infected with parainfluenza virus type 3. Nucleic acid amplification techniques represent important tools for the timely and sensitive diagnosis of influenza A virus infections and, therefore, their management and control.

Rapid detection of parainfluenza virus type 3 RNA in respiratory specimens: use of reverse transcription-PCR-enzyme immunoassay

Parainfluenza virus type 3 (PIV-3), an important lower respiratory tract pathogen in young children and immunocompromised individuals, may be underdiagnosed because of the insensitivity of available culturing systems and delay in identification of virus in cell culture. We developed a reverse transcription-PCR-enzyme immunoassay (RT-PCR-EIA) for PIV-3, using primers specific for a highly conserved region of the hemagglutinin-neuraminidase gene. Testing of nasal washes spiked with PIV-3 or other respiratory viruses showed that this assay detected seven strains of PIV-3 but not other respiratory viruses. Of 103 respiratory tract samples obtained from children experimentally infected with a liver PIV-3 vaccine or naturally infected with wild-type PIV-3, 51 were positive by culture and 48 were positive by RT-PCR-EIA. Eleven of the culture-positive samples were negative by RT-PCR-EIA; however, none of these grew virus upon reinoculation into cell culture, indicating that virus was lost or was present at a very low titer. Eight of the culture-negative samples were positive by RT-PCR-EIA: two were obtained from a subject who was culture negative but had a serologic response to PIV-3, four were obtained 7 to 9 days after the first positive culture, and two were obtained 1 day prior to the first positive culture. Thus, this RT-PCR-EIA for PIV-3 is sensitive and specific and can detect viral RNA in samples from which virus cannot be cultivated. This assay could be used for diagnosis late in the course of PIV-3 infection and for accurate detection of disease outbreaks.

Necrotizing enterocolitis: research agenda for a disease of unknown etiology and pathogenesis

Necrotizing enterocolitis (NEC) is a significant neonatal public health problem that affects low-birth weight infants in neonatal intensive care units throughout the country. As the survival rate of low-birth weight infants continues to increase and as the number of low-birth weight births remains unchanged, we can anticipate that NEC will continue to be a cause of significant morbidity and mortality in the future. Despite many reports about NEC that describe demographic risk factors and short-term or long-term outcome, there is a paucity of basic science information about neonatal gastrointestinal physiology and pathophysiology in human preterm and even full-term infants. It has become increasingly evident that we need a much better understanding about the developmental aspects of gastrointestinal function in health and disease before we can achieve further advances in our understanding of and thus rational therapy for and prevention of NEC. The purpose of the National Institute of Child Health and Human Development conference "Necrotizing Enterocolitis: Basic Science Approaches to Gut Maturation and Pathogenesis" was to bring together basic science investigators, clinical epidemiologists, and clinical scientists to identify important areas of research that need to be applied to the problem of NEC. The concept of applying the "bench to bedside" type of collaborative research was emphasized and encouraged because many clinical neonatologists may have little scientific interaction with basic scientists. In addition, many basic scientists may be unaware of NEC and the implications for targeted research related to this disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Borna disease virus in peripheral blood mononuclear and bone marrow cells of neonatally and chronically infected rats

Borna disease virus (BDV) establishes a persistent infection in cells of the nervous system in rats. The response, or lack thereof, of the immune system to BDV infection of neurons is responsible for the presence or absence, respectively, of Borna disease. We recently demonstrated transmission of BDV by bone marrow cells from neonatally infected rats. Our findings suggested the possibility of a heretofore unsuspected interaction between BDV and the immune system, that of direct effects of BDV infection on the cells of the immune system. This report enlarges upon the previous findings and confirms the presence of BDV RNA in bone marrow cells of neonatally infected rats, using a reverse transcription-polymerization chain reaction-enzyme immunosorbent assay (RT-PCR-EIA). In addition, we detected BDV RNA in peripheral blood mononuclear cells of neonatally infected rats, and in rats inoculated as adults in the chronic, but not the acute, stage of infection. In addition, the RT-PCR-EIA technique identified BDV RNA in cerebrospinal fluid, nasal secretions, saliva, urine and stool. BDV-sequences were not detected in the plasma of infected animals nor in the body fluids and tissues of normal rats.

Human milk mucin inhibits rotavirus replication and prevents experimental gastroenteritis

Acute gastrointestinal infections due to rotaviruses and other enteric pathogens are major causes of morbidity and mortality in infants and young children throughout the world. Breast-feeding can reduce the rate of serious gastroenteritis in infants; however, the degrees of protection offered against rotavirus infection vary in different populations. The mechanisms associated with milk-mediated protection against viral gastroenteritis have not been fully elucidated. We have isolated a macromolecular component of human milk that inhibits the replication of rotaviruses in tissue culture and prevents the development of gastroenteritis in an animal model system. Purification of the component indicates that the antiviral activity is associated with an acidic fraction (pI = 4.0-4.6), which is free of detectable immunoglobulins. Furthermore, high levels of antiviral activity are associated with an affinity-purified complex of human milk mucin. Deglycosylation of the mucin complex results in the loss of antiviral activity. Further purification indicated that rotavirus specifically binds to the milk mucin complex as well as to the 46-kD glycoprotein component of the complex. Binding to the 46-kD component was substantially reduced after chemical hydrolysis of sialic acid. We have documented that human milk mucin can bind to rotavirus and inhibit viral replication in vitro and in vivo. Variations in milk mucin glycoproteins may be associated with different levels of protection against infection with gastrointestinal pathogens.

Cell surface ligands for rotavirus: mouse intestinal glycolipids and synthetic carbohydrate analogs

Rotaviral binding to receptors on epithelial cells in the small intestine is thought to be a key event in the infection process and may be carbohydrate-mediated. Strain SA11 of rotavirus bound in vitro both to glycolipids isolated from mouse small intestine and to authentic glycolipids using thin layer chromatography overlay and microtiter well adsorption assays. Neutral mouse intestinal glycolipids which bound rotavirus were GA1 (Gal beta 1----3GalNAc beta 1---4Glc beta 1----4Glc beta 1----1-ceramide) and pentaosylceramides with terminal N-acetylgalactosamine, while acidic lipids which bound rotavirus included cholesterol 3-sulfate and two compounds termed bands 80 and 81. Digestion with ceramide glycanase suggested that bands 80 and 81 have lactosyl ceramide cores and an unidentified acidic moiety(s). No sialic-acid-containing glycolipids tested were active in viral binding. Band 81, which may have a ganglio core, bound rotavirus with greatest avidity, followed by GA1. Of authentic glycolipids assayed, only GA1 and GA2 (GalNAc beta 1----4Gal beta 1----4Glc beta 1----1-ceramide) displayed rotaviral binding. A phosphatidylethanolamide dipalmitoyl-containing neoglycolipid analog of GA2 bound rotavirus with avidity similar to native GA2. Substitution of beta 1----4-linked GlcNAc or beta 1----3-linked GalNAc for terminal GalNAc of GA2 neoglycolipid supported rotaviral binding, while other substitutions abrogated it. These findings suggest that a carbohydrate epitope similar to that of GA2 is sufficient for in vitro rotaviral binding, although binding may be enhanced by galactose and/or an acidic moiety in a secondary epitope.

Baculovirus expression of pestivirus non-structural proteins

Bovine viral diarrhoea virus (BVDV) belongs to the pestivirus group, a genus within the Flaviviridae family. It possesses a positive-sense ssRNA genome with a single large open reading frame (ORF) encoding about 4000 amino acids. Here we report the continuation of our studies of pestivirus protein biogenesis, involving expression from the viral non-structural protein-encoding region. The 3'-terminal 60% of the BVDV ORF was cloned into a plasmid transfer vector which was then used to construct a recombinant baculovirus. Infection of Spodoptera frugiperda Sf9 cells with this recombinant virus resulted in the production of the expected mature viral proteins. Polyprotein processing by the BVDV p80 proteinase appeared to be nearly identical to that observed in authentic BVDV-infected bovine cells, and as previously shown to occur when expression of the same region was studied in a mammalian cell transient expression system. However, one viral proteolytic cleavage did not occur in the baculovirus-infected insect cells; the viral p80 proteinase failed to act at its own N terminus. This recombinant baculovirus/insect cell expression system provides an abundant source of BVDV non-structural proteins. Therefore we explored the utility of the proteins produced in this system for the detection of anti-BVDV antibodies in bovine sera. In preliminary experiments using these antigens in an ELISA we found a positive correlation between the presence of ELISA-reactive antibody and virus-neutralizing activity.

A human milk factor inhibits binding of human immunodeficiency virus to the CD4 receptor

Perinatal transmission of human immunodeficiency virus (HIV) from infected mothers to their children occurs at rates reported as 20-50%. The role of breast feeding in perinatal transmission of viral infections has not been well established. We studied 34 milk and colostral samples obtained from HIV-seropositive and HIV-seronegative women to determine if they contained anti-HIV activity. We found that all the samples contained a factor that inhibited the binding of HIV epitope-specific MAb to recombinant CD4 receptor molecules. The titers of inhibitory activity ranged from 1:200 to 1:10,000 and did not differ between HIV-seropositive and HIV-seronegative mothers. This milk factor also inhibited the binding of gp120 to CD4. Neither human sera nor bovine milk exhibited appreciable inhibitory activity. Fractionation of human milk indicated that the inhibitory activity was confined to the macromolecular fraction; little activity was found in isolated milk lipids or oligosaccharides. Chromatographic procedures indicated that the active macromolecule has an isoelectric point of 9.3-9.6. The active material did not bind to concanavalin A; however, the activity was partially destroyed by chemical and enzymatic treatments that removed sulfated residues. The active material may thus be a sulfated protein, glycoprotein, mucin, or glycosaminoglycan that inhibits the binding of CD4 to HIV envelope glycoproteins. The role of this factor in the natural history of HIV infection in infants and children should be the subject of additional investigations.

Focal encephalitis with enterovirus infections

We report on four pediatric patients with Enterovirus infections who were admitted to the hospital with signs or symptoms of acute, focal encephalitis. All four experienced focal seizures. Each had a cerebrospinal fluid pleocytosis at the initial lumbar puncture. In all four patients the diagnosis of herpes simplex encephalitis was entertained. Each child improved spontaneously within a few days of admission to the hospital, and only one had residual neurologic abnormalities at the time of discharge. A brief review of these cases, and three additional cases from the literature, indicate that the enteroviruses, particularly the group A Coxsackieviruses, are rare causes of acute focal encephalitis in children and adolescents.

The polymerase chain reaction: a new tool for the understanding and diagnosis of HIV-1 infection at the molecular level

The polymerase chain reaction (PCR) is at present the most powerful analytical tool for detection of specific nucleic acid sequences. The method is based on the in vitro amplification of DNA segments before detection with conventional hybridization techniques or visualization following electrophoresis and staining. The current diagnostic methods for HIV-1 do not allow easy identification of subgroups of infected patients including infants born to seropositive mothers, individuals with delayed serological responses to the virus, infected patients with indeterminate serology results, and patients with dual retroviral infections. Furthermore, response to antiviral therapy cannot be evaluated with serological assays. The rationale for applying PCR in those situations is elaborated here. The applications of this technique for HIV-1 as a diagnostic test and for the understanding of the pathogenesis of this retrovirus are described. Potential limitations of this technique for diagnostic purposes include mainly the possibility of false-positive results due to contamination and false-negative reactions caused by Taq polymerase inhibition. Non-isotopic means for detection of amplified products have been described and should allow for a wider application of this technology. Modifications of PCR which make use of internal standards seem promising for quantitative analysis of nucleic acids. PCR has great potential for viral diagnosis but still requires further studies and better characterization.

Persistent diarrhea and fecal shedding of retroviral nucleic acids in children infected with human immunodeficiency virus

Gastrointestinal dysfunction is a serious problem in many children infected with human immunodeficiency virus (HIV), the etiology of which has not been clearly defined. Quantitative nucleic acid amplification was used to study the correlation between shedding of HIV nucleic acids and gastrointestinal symptoms in HIV-infected infants and children. Many with HIV infection and persistent diarrheal disease shed HIV nucleic acids in their feces, as did an HIV-infected patient without apparent diarrheal disease. HIV nucleic acids were not found in feces of non-HIV-infected individuals. Intestinal infection with HIV appears to be important in the pathophysiology of gastrointestinal dysfunction in infants and children with HIV infection. Furthermore, the fecal shedding of HIV may play a role in HIV transmission in environments prone to high levels of fecal-oral contamination.