Vertical transmission of HIV: a prospective study

Isothermal amplification using a chemical heating device for point-of-care detection of HIV-1

Background

To date, the use of traditional nucleic acid amplification tests (NAAT) for detection of HIV-1 DNA or RNA has been restricted to laboratory settings due to time, equipment, and technical expertise requirements. The availability of a rapid NAAT with applicability for resource-limited or point-of-care (POC) settings would fill a great need in HIV diagnostics, allowing for timely diagnosis or confirmation of infection status, as well as facilitating the diagnosis of acute infection, screening and evaluation of infants born to HIV-infected mothers. Isothermal amplification methods, such as reverse-transcription, loop-mediated isothermal amplification (RT-LAMP), exhibit characteristics that are ideal for POC settings, since they are typically quicker, easier to perform, and allow for integration into low-tech, portable heating devices.

Methodology/Significant Findings

In this study, we evaluated the HIV-1 RT-LAMP assay using portable, non-instrumented nucleic acid amplification (NINA) heating devices that generate heat from the exothermic reaction of calcium oxide and water. The NINA heating devices exhibited stable temperatures throughout the amplification reaction and consistent amplification results between three separate devices and a thermalcycler. The performance of the NINA heaters was validated using whole blood specimens from HIV-1 infected patients.

Conclusion

The RT-LAMP isothermal amplification method used in conjunction with a chemical heating device provides a portable, rapid and robust NAAT platform that has the potential to facilitate HIV-1 testing in resource-limited settings and POC.

The early natural history of vertically transmitted HIV-1 infection in African children from Durban, South Africa

Forty-eight children with vertically transmitted HIV-1 infection and 93 uninfected infants were followed up at regular intervals from birth for a mean of 26 months. They were examined physically, growth and development were assessed and illnesses recorded. Seventy per cent of infected infants were symptomatic by 6 months. Relative risks in the infected infants were highest for lymphadenopathy (4.56; CI 2.7-7.7), failure to thrive (4.48; 2.57-7.81), and neurological abnormalities (3.32; 1.9-5.58). The most frequent findings were diarrhoea (78%), pneumonia (76%) and lymphadenopathy (70%). Thrush and pneumonia occurred early but declined over time, whereas diarrhoea and neurological abnormalities occurred later and increased in frequency. A diagnosis of AIDS was made in 44% of infected infants by 12 months of age. Mortality in infected infants was 35.4%, and 76% of deaths occurred within the 1st year. About two-thirds of HIV-infected infants survived into early childhood. In South African children with vertically acquired HIV-1 infection the onset of disease is early and deterioration to AIDS and death are rapid. Infected infants can be easily recognized clinically, the majority by 6 months of age.

The needs of children whose mothers have HIV infection

AIM

To ascertain the psychological, social, and educational needs of children born to mothers with HIV infection.

METHODS

Review of case records of 120 children and 86 mothers.

RESULTS

The cohort of 120 children were born to 92 women, and followed up for a median duration of 48 months (mean (SD) 51.1 (34.1), range 0.3-132). Sixteen children were infected with HIV, 15 were of indeterminate status, and 89 uninfected. Eighty one children (68%) were cared for by their birth mother, of whom 52% were single women and 23 (38% of 61) known to have symptomatic HIV disease. Twenty five mothers of 32 children had died; the child's mean (SD) age at maternal death was 66.9 months (37.7) (range 4-128). Compared with uninfected children, more infected children knew of their mother's diagnosis (31% v 5%) and mothers were also more likely to disclose their own illness to educational authorities (77% v 13%). A larger proportion of infected children had special educational needs (69% v 13%). Only 33 children (28%) were known not to be receiving any support from the voluntary or statutory agencies.

CONCLUSION

The results highlight the multiple needs of children living with maternal HIV infection, which require dedicated resources and commitment from health, education, and social work agencies and the voluntary sector. We propose the model of chronic illness as the standard of care for these children.

HIV in the neonate

Mother-to-infant transmission of human immunodeficiency virus (HIV) is a worldwide problem. Between 7 and 40% of infants born to HIV-positive mothers become infected. The prognosis of these infants is poor, with most developing early and rapidly progressive disease. A number of advances in diagnosis and therapy offer opportunities to reduce the rate of vertical transmission and to improve the outlook of infected infants. Antiretroviral therapy during pregnancy and the neonatal period can markedly reduce the risk of mother-to-infant transmission. Recognition that 50% or more of infections are transmitted peripartum offers scope to further reduce the rate of transmission. However there is currently no consensus on the optimal management of pregnancy in HIV-infected women, and there is an urgent need for large randomized controlled trials. The development of polymerase chain reaction and p24 antigen assays has greatly facilitated the diagnosis of neonatal HIV infection, thereby enabling earlier supportive and anti-retroviral therapy. The place of zidovudine in paediatric HIV infection is now well-established, but the future will undoubtedly bring combination anti-retroviral therapy. Optimism about the prospects for developments in the prevention and treatment of paediatric acquired immunodeficiency syndrome must be tempered by the fact that the majority of cases occur in countries where patients have little or no access to medical care.

Inhibition of murine embryonic growth by human immunodeficiency virus envelope protein and its prevention by vasoactive intestinal peptide and activity-dependent neurotrophic factor

Intrauterine growth retardation and neurodevelopmental handicaps are common among infants born to HIV-positive mothers and may be due to the actions of virions and/or maternally derived viral products. The viral envelope protein, gp120, is toxic to neurons, induces neuronal dystrophy, and retards behavioral development in neonatal rats. Vasoactive intestinal peptide, a neuropeptide regulator of early postimplantation embryonic growth, and the neuroprotective protein, activity-dependent neurotrophic factor, prevent gp120-induced neurotoxicity. Whole embryo culture of gestational day 9.5 mouse embryos was used to assess the effect of gp120 on growth. Embryos treated with gp120 exhibited a dose-dependent inhibition of growth. gp120-treated embryos (10(-8) M) grew 1.2 somites in the 6-h incubation period, compared with 3.9 somites by control embryos. Embryos treated with gp120 were significantly smaller in cross-sectional area and had significantly less DNA and protein than controls. Growth inhibition induced by gp120 was prevented by cotreatment with vasoactive intestinal peptide or activity-dependent neurotrophic factor. gp120 may play a role in the growth retardation and developmental delays experienced by infants born to HIV-positive mothers. Vasoactive intestinal peptide and related factors may provide a therapeutic strategy in preventing developmental deficits.

Age-related pattern of immunoglobulins G, A and M in children born to HIV-seropositive women

In a cohort of 56 children born to HIV-seropositive African women, 19 met the criteria for HIV-infected children and 37 remained antibody-negative at 18 months of age. Blood samples taken at birth and 3-monthly until 18 months of age were processed and analysed by laser nephelometry for serum immunoglobulin (IgG, IgA and IgM) levels. In the infected group of children. higher levels of IgG were observed during their 1st 18 months of life reaching statistical significance at 3, 6, 15 and 18 months. Higher levels of IgA at 3 months and at 15 and 18 months, and higher levels of IgM at 3 months and 18 months later were statistically significant. All four infected children who died before the age of 6 months showed signs of hypergammaglobulinaemia (IgG and IgA) by 3 months of age. In this study the earliest and most common immunological abnormality was hypergammaglobulinaemia and infected infants with higher morbidity and mortality had more evident immunoglobulin abnormalities than infected children who survived. However, the immunological abnormalities in this small cohort did not precede the onset of severe symptoms and cannot therefore be used to predict clinical outcome.

Pediatric HIV infection

Developments in the prevention and treatment of HIV infection in pregnant women and their children are encouraging. Perinatal ZDV therapy can reduce the maternal-infant transmission rate by two thirds in select populations. New therapies and the development of diagnostic assays to monitor HIV viral burden have renewed hope that, by aggressively controlling viremia, the progressive immunodeficiency can be delayed or even prevented. The general pediatric approach of preventing illnesses through aggressive vaccination and education policies must be actively incorporated into an approach to this epidemic. Success in controlling the pediatric HIV epidemic requires a concerted, coordinated effort by public policy makers, health care providers, basic science researchers, and those who are HIV-infected.

The diagnosis and management of HIV infection

In the past 15 years HIV infection and AIDS have become pandemic in the world. Infectious and neoplastic complications have evolved in response to medical advances and to the appearance of HIV infection in different populations. Because AIDS patients live longer with severe immunosuppression and new treatments have controlled opportunistic infections, the spectrum of complications of AIDS has changed. New and more effective antiretroviral drugs are being developed, and physicians are learning how to use them more effectively. Currently, medical management of HIV-infected patients focuses on the appropriate use of antiretrovirals and the prevention, early diagnosis, and treatment of complicating illnesses. A coordinated continuum of care and patient education and involvement are also key elements of effective management of HIV infection.

Maternal HIV and drug use: effect on health and social morbidity

A retrospective analysis of routine child health surveillance information was performed on health visitor records of 459 children, to examine the independent effects of maternal HIV infection and drug use during pregnancy on morbidity in the first 3 years of life. No significant differences were observed in the developmental progress of children born to HIV infected or drug using women when compared to community controls. The pattern of medical consultations in the first 18 months of life was significantly different, maternal drug use exerting a negative influence on outpatient visits (odds ratio 0.6, 95% confidence interval 0.4 to 1.0). At 6 weeks, the majority of children lived with their birth parent(s), and no differences were observed between the groups. By 10 months of age, only 81% of children born to HIV infected drug using women lived with their parent(s). While maternal drug use and HIV did not have adverse effects on child health and development, these findings highlight the social implications for children affected by the heterosexual spread of HIV.

Maternal HIV infection, drug use, and growth of uninfected children in their first 3 years

OBJECTIVE

To determine the separate effects of maternal HIV infection and drug use during pregnancy on growth of uninfected children in their first 3 years.

DESIGN

Retrospective analysis of measurements from health visitor records made during routine child health surveillance at 6 weeks, 10 months, and 3 years of age. Multilevel analysis allowed for between-infant variation in fitted growth lines, and adjustment for other factors. Growth was described in terms of an intercept (z score at term) and growth slopes (change in z score per year) up to, and from, 4 months.

SUBJECTS

290 case babies delivered in Edinburgh hospitals to women who reported injection drug use by either themselves or their HIV infected partner, and 186 community controls. A total of 131 (45%) of the case babies were born to women who used drugs, predominantly opiates, during pregnancy and 93 (32%) to HIV infected women. The eight infected children were excluded from analysis.

MAIN OUTCOME MEASURES

Age and sex standardised z scores for height, weight, and body mass index.

RESULTS

459 (96%) of the 476 records for cases and controls were traced, yielding 1432 weight and 939 height measurements. Maternal HIV infection was not found to affect growth; at 3 years the estimated effect on weight z score was 0.16 with 95% confidence interval (-0.25 to 0.57) and for height 0.18 (-0.19 to 0.55). Drug use during pregnancy was associated with lighter babies at 40 weeks followed by depressed growth in the first four months, these infants remaining just slightly smaller at 3 years with an estimated effect on z scores of -0.5 for weight with 95% confidence interval (-0.89 to -0.11) and -0.37 (-0.72 to -0.02) for height.

CONCLUSIONS

Maternal HIV infection does not adversely affect growth in uninfected infants, and the effect of drug use during pregnancy is limited to small decrease in size at 3 years.

Prognostic value of immunological data, in vitro antibody production, and virus culture in vertical infection with HIV-1

The prognostic value of immunological indices, in vitro antibody production, and virus culture pattern at 3 months of age was estimated in 35 infants infected by HIV-1 from a cohort of 298 babies born to HIV-1 seropositive mothers and followed up from birth. At 1 year old, 15 of these infants were classified as stage P-1 (according to the Centers for Disease Control classification) seven were P-2A, and seven had AIDS. Significantly higher CD8 percentages, lower percentages and absolute value of CD4, and lower CD4/CD8 ratios at 3 months were observed in infants with severe symptoms at 1 year of age when compared with those who were asymptomatic at this age. Seventy seven per cent of infants with a 'rapid' virus culture when 3 months old had developed AIDS or had died by 1 year of age and only 8% of those with 'slow' virus culture had AIDS when 1 year old. Moreover, 100% of those who were asymptomatic at 1 year had a slow virus culture at 3 months. Significant statistical association was found between the virus replication pattern at 3 months and the clinical stage at 1 year of age.

Cytotoxic T lymphocyte activity and CD8 subpopulations in children at risk of HIV infection

HIV-specific cytotoxic T lymphocytes (CTL) are thought to play a major role in viral control in HIV-infected adults. Changes in the relative proportions of CD8 lymphocyte subpopulations are also thought to be associated with disease progression. Less is known about the relative effectiveness of CTL against different HIV targets, or about the relationship, if any, between CTL activity and CD8 subpopulations. We have measured CTL activity against four HIV gene products (gag, tat, pol and env) and expression of CD45RO, CD45RA, HLA-DR, CD29, S6F1, and CD57 surface markers on CD8 cells from nine HIV-infected and 11 HIV-uninfected children. Of nine HIV-infected children, six showed antigen-specific CTL activity on at least one occasion: 4/6 directed against tat, 6/6 against pol, 1/6 against env, and 1/6 against gag. However, the specificity of the CTL activity varied between children and within individual children with time. Furthermore, two uninfected children showed CTL activity, one to HIV-gag, -pol and -tat, and the other to HIV-pol. All the HIV-infected and two uninfected children had abnormal proportions of CD8 subpopulations in whole blood compared with age-matched controls. There was no correlation between CTL activity and CD8 subsets in whole blood. Five children changed from CTL-positive to CTL-negative (or vice versa) during the study. In these, the occasions when CTL activity was detected coincided with an increase in CD8 cells, an expansion of HLA-DR+ CD8 cells and a loss of CD45RA+ CD8 cells.

Early diagnosis of severe combined immunodeficiency syndrome

Infants with severe combined immunodeficiency syndrome (SCIDS) have a greatly improved prognosis if diagnosed and treated before they develop overwhelming infection. Clinical and laboratory data on 45 patients with SCIDS were retrospectively reviewed to assess the value of absolute lymphocyte counts in making an early diagnosis. Ninety infants matched for age, sex, and presenting symptoms were used as controls. Thirteen (29%) infants with SCIDS were diagnosed at birth as previous siblings had been affected; 32 (71%) were diagnosed after the development of symptoms. Eighteen (56%) of these remained undiagnosed until after 6 months of age. The first symptoms occurred at a median of 5 weeks (range 1 day to 8 months) and the first admission to hospital was at 4 months (range 1 week to 16 months). Symptoms included respiratory infection (91%), vomiting and diarrhoea (81%), failure to thrive (88%), candidiasis (50%), and skin lesions (28%). The mean lymphocyte count was 1.71 x 10(9)/l compared with 7.2 x 10(9)/l in controls. Excluding one child with Omenn's syndrome (lymphocyte count 23.3 x 10(9)/l, all symptomatic infants with SCIDS had lymphocyte counts less than 2.8 x 10(9)/l at presentation. The median delay between the first abnormal lymphocyte count and diagnosis was seven weeks (range one day to 13 months). Twenty eight (88%) of 32 infants would have been diagnosed before 6 months of age if investigated after the first low lymphocyte count. These data indicate that low lymphocyte counts are predictive of SCIDS. Paediatricians are urged to pay attention to the absolute lymphocyte counts in all infants in whom a full blood count is performed. Those with lymphocyte counts persistently less than 2.8 x 10(9)l should be investigated for SCIDS.

Mucosal infection of neonatal rhesus monkeys with cell-free SIV

Although the mechanisms for maternal transmission are unknown, approximately half of the infants congenitally infected with the human immunodeficiency virus type 1 (HIV-1) seem to become infected late in gestation or during delivery. Previously, we have developed a rhesus monkey model for congenital infection by injecting cell-free simian immunodeficiency virus (SIV) directly into amniotic fluid. Our results suggested that fetal infection may have occurred via skin or mucous membrane exposure. Mucosal surfaces have also been implicated as a portal of virus entry by a study in which the presence of serosanguinous fluid in neonatal gastric aspirates correlated with an increased rate of HIV-1 transmission. To test whether cell-free virus could transverse intact neonatal mucosal surfaces, we administered SIVmac251 orally to four rhesus monkey neonates within 1 hr following cesarean section delivery. All four neonates developed viremia and were positive by cocultivation and PCR. Seroconversion occurred in three of the four neonates. The SIV dose given was within physiological range as shown by end-point dilution of virus stock and viremic plasma samples of juvenile rhesus monkeys. This primate model for mucosal transmission of cell-free virus features a high infection rate, thus making studies of mucosal immunity and the development of strategies to prevent intrapartum virus transmission possible.

Diagnosis and prediction of pediatric HIV-1 infection and AIDS: current status

The increase in the incidence of HIV-1 infection in women of child bearing age has resulted in a surge in the number of cases of pediatric AIDS. The World Health Organization (WHO) has estimated that the number of cases of pediatric AIDS worldwide will be at least 10 million by the year 2000. This alarming statistic underscores the need for accurate prediction and diagnosis of pediatric HIV-1 infection which is of paramount importance for the initiation of effective therapeutic interventions. Since circulating maternal anti-HIV-1 antibody persists in the baby for up to 21 months, early conventional serological diagnosis of infection is not possible. Other methods for diagnosis of HIV-1 infection in a child less than 2 years of age have been utilized including the polymerase chain reaction (PCR), measurements of the HIV-1 p24 core protein and anti-HIV-1 IgA, as well in vitro measurements of antibody producing cells. In addition, the ability to predict HIV-1 infection in the child based upon maternal humoral immune responses to the envelope glycoprotein has also been suggested. This review summarizes the recent serological, biological and molecular methodologies used to predict and diagnose pediatric HIV-1 infection and AIDS.

Measles, mumps and rubella immunisation in children at risk of infection with human immunodeficiency virus

A retrospective serological study of 81 children at risk of HIV (II HIV-infected, 70 HIV-negative) was performed to assess susceptibility to measles, mumps and rubella and response to measles, mumps and rubella (MMR) immunisation. There was no difference in the initial serological response between the HIV-infected and HIV-negative children. Repeat serology should be performed on HIV-infected children as during follow-up antibodies may be lost. Reimmunisation should be considered for the seronegative.

Maternal factors in HIV transmission

In order to identify features associated with an increased risk of transmission of HIV from seropositive women to their offspring, 70 children of 58 HIV seropositive mothers were studied. Fifty-six children were followed prospectively from pregnancy; in 14 identified after the puerperium, obstetric notes were reviewed and stored serum was tested. Twelve infants of 10 mothers were HIV infected. Risk of transmission was increased in the first year after seroconversion; 5/9 infants born at this time were infected compared with 7/61 born subsequently (P < 0.001). Progression to stage IV in transmitters was more likely, occurring in the mothers of 9 infected children at a median of 3 years (range 0.5-6.5) and in mothers of 19 non-infected children at a median of 5 years (range 1-7) (P = 0.032). Maternal CD4+ counts < 400 x 10(6)/l were found in 7/12 transmitting and 7/49 non-transmitting pregnancies (P < 0.01). Differences in HIV antigenaemia did not reach significance. These factors may influence the counselling of mothers regarding their child's and their own prognosis.

HIV antibody testing in the antenatal clinic

With the increase in human immunodeficiency virus (HIV) seroprevalence amongst women attending the antenatal clinic in the UK it is essential that women are adequately prepared to make an informed decision about being tested for HIV and to receive the result of such testing. This paper discusses the purpose of testing, the necessity of pre-test counselling, its content and the practical implications of providing it. Guidelines for the content of a pre-test counselling session are outlined with particular reference to issues pertinent to the pregnant woman: vertical transmission, the effect of pregnancy on disease progression, the effect of HIV on pregnancy, the prognosis for an infected child and so on.

HIV-1 infection and perinatal mortality in Zimbabwe

As part of a survey of the causes of perinatal mortality at Mpilo Maternity Hospital, 220 neonatal deaths and the mothers of 221 stillbirths were tested for HIV-1 antibodies. The HIV positive rate in neonatal deaths was 23.6% (95% confidence interval (CI) 18.0 to 29.2%), significantly higher than 15.4% (95% CI 10.6 to 20.1%) in stillbirths. Perinatal deaths from congenital malformations, birth asphyxia, pregnancy induced hypertension, placental abruption, and oFther non-infectious causes had similar low HIV positive rates averaging 8.1% (95% CI 3.9 to 12.3%). Deaths from septicaemia had a significantly greater rate of 39.3% (95% CI 27.0 to 51.6%) and the highest rate of 72.2% (95% CI 51.5 to 92.9%) was found in deaths from congenital infection other than syphilis, indicating that maternal HIV infection predisposes to neonatal septicaemia and congenital infection. Unexplained stillbirths also had a significantly greater rate of 22.4% (95% CI 10.7 to 34.1%), presumably because some died from unrecognised infection. The rate in deaths from congenital syphilis was 17.4% (95% CI 9.6 to 25.2%), indicating a significant but weak association between these two sexually transmitted diseases in Bulawayo. The rate in deaths from hyaline membrane disease was not significantly greater at 15.0% (95% CI 6.0 to 24.0%). By predisposing to infection, maternal HIV infection was estimated to increase the stillbirth rate by 1.6 times and the neonatal mortality rate by 2.7 times. It predisposed equally to early and late onset neonatal septicaemia, but more to infection from streptococci and staphylococci than from Gram negative enterobacteria. HIV positive deaths from congenital infection had respiratory distress and usually intrauterine growth retardation, hepatosplenomegaly, and congenital pneumonia on lung histology.

Risk factors for mother-to-child transmission of HIV-1

Children born to women known to be infected with human immunodeficiency virus type 1 (HIV-1) before delivery were followed prospectively from birth in nineteen European centres. This analysis, encompassing the period end-December, 1984, to beginning-August, 1991, focuses on risk factors for mother-to-child transmission of HIV-1 infection. Rate of vertical transmission, based on 721 children born to 701 mothers more than 18 months before the time of analysis, was 14.4% (95% Cl 12.0-17.1%). Transmission was associated with maternal p24-antigenaemia and a CD4 count of less than 700/microliters. In a multivariate analysis, odds ratios of transmission were: 2.25 (95% Cl 0.97-5.23) in breastfed children vs never-breastfed children; 3.80 (1.62-8.91) in children born before 34 weeks' gestation; and 0.56 (0.30-1.04) in children delivered by caesarean section. Transmission was higher with vaginal deliveries in which episiotomy, scalp electrodes, forceps, or vacuum extractors were used, but only in centres where these procedures were not routine. On the basis of these results, HIV-infected women contemplating pregnancy should be counselled according to their immunological findings and, if they have p24-antigenaemia or a low CD4 count, warned of an increased risk of viral transmission. Caesarean deliveries may have a protective effect, although it is premature to recommend routine operative delivery. The mechanism for the higher infection rate in children born before 34 weeks' gestation is unclear, but could reflect inadequate passive or active immunity at that age, combined with substantial transmission during labour or delivery. The balance of evidence suggests that mothers with established infection can transmit HIV infection through breastmilk, although the relative importance of this route remains to be defined.

Genetic risk factors for perinatally acquired HIV-1 infection

This study evaluates genetic influence on susceptibility to perinatal HIV-1 infection among 106 Black infants from New York and San Francisco born to mothers infected with HIV-1. Genes tested by molecular techniques are HLA class II loci DRB1, DPB1 and DQA1; HLA class III loci complement C4A and C4B; alpha and beta interferons; and the constant region of the T-cell receptor beta chain. Of the 106 infants analysed, 54 are infected with HIV and 52 remain uninfected at age 15 months and older. Genotypes in the HLA region appear to influence risk of HIV infection. Specifically, infants with the amino acid sequence -asp-glu-ala-val- at DPB1 positions #84-87 are more likely to be infected (P = 0.001) and infants with the allele DQA1*0102 are less likely to be infected (P = 0.031). Combinations of these two risk factors show a strong dose response (P = 0.0005). HLA DPB1 and DQA1 may play a direct role in immune response associated with HIV-1 infection, or the critical region may be located between these two genes. Characterisation of other class II HLA genes in these infants will allow more precise determination of the role of HLA loci in susceptibility to HIV-1 infection.

Vertical transmission

Since AIDS was first described in children, much has been learnt about the epidemiology, clinical presentations and natural history of perinatally acquired HIV disease. As yet, several questions remain unanswered about the pathogenesis of vertical transmission, the relative risk associated with each mode of transmission, the rate of transmission from mother to child, and the factors that might contribute to the efficiency of transmission. Data presented thus far suggest that intrauterine exposure poses the greatest risk, but more recent reports have reopened speculation that infection could occur at or around the time of delivery. The prospects for intervention, to stop transmission from mother to child, rest on the ability to identify HIV-infected women; the knowledge of how and when the virus infects the fetus; and how to identify, as early as possible, those truly infected infants. Resources should therefore be set aside for routine screening for HIV in antenatal women. There is also a need to quantify the contribution made by intrauterine versus intrapartum events. Lastly, promising new techniques designed to detect neonatal HIV infection must be properly evaluated against standard methods, and correlated with clinical outcome. Only then can the efficacy of antiretroviral therapy be tried, to prevent vertical transmission.

Selective transmission of human immunodeficiency virus type-1 variants from mothers to infants

Multiple human immunodeficiency virus type-1 sequences from the V3 and V4-V5 regions of the envelope gene were analyzed from three mother-infant pairs. The infants' viral sequences were less diverse than those of their mothers. In two pairs, a proviral form infrequently found in the mother predominated in her infant. A conserved N-linked glycosylation site within the V3 region, present in each mother's sequence set, was absent in all of the infants' sequence sets. These findings demonstrate that a minor subset of maternal virus is transmitted to the infant.

HIV-1 infection. Diagnosis and management

This article discusses the epidemiology, diagnostic methods, prevention of complications, and medical management of HIV-1 infection. Many different therapeutic strategies for HIV-1 infection are being evaluated, but until the immune suppression is eradicated, presumably through more effective antiviral therapy, complications of AIDS and HIV-1 infection will continue to be encountered.

Virus infections of the respiratory tract in HIV-infected children

In order to determine whether the rates of respiratory viral infection and the severity of respiratory symptoms in HIV-infected children were higher than those in noninfected children, nose and throat swabs for viral isolation were taken at 3-month intervals during the first 2 years of life from 50 children born to HIV-infected women. Similar samples were obtained during the first year of life from 19 control children born to HIV seronegative mothers. Of the 50 children, five proved to be HIV-infected while 45 were presumed to be uninfected. HIV-infected children had significantly more respiratory symptoms and a higher proportion of samples from which viruses were isolated than the non-HIV-infected children. Also, more infected episodes required admission to hospital in the HIV-infected group. There was no such difference between the non-HIV-infected and the control children. Three HIV-infected children received intravenous immunoglobulin therapy. Among these the proportion of positive samples for viral isolation was greater before than after treatment began. These results suggest that HIV-infected children are more susceptible to recurrent viral infection and that passive immunotherapy may be of benefit to such children.

Immunological follow-up in children born to HIV-1 infected mothers

From November 1985 to January 1990 we examined 156 children born to 154 HIV-1 seropositive mothers every 3 months. Eighty-seven infants were over 18 months by January 1990. Six of them met the CDC criteria of HIV-1 infection or died from AIDS; a transmission rate of 7%. Six of the children aged less than 18 months also met the CDC criteria of HIV-1 infection. These 12 infected children were compared with the 81 presumably unifected children. The perinatal findings were similar in both groups. Most of the HIV-1 infected babies showed early abnormalities in humoral and cellular immunity, hypergammaglobulinemia, low percentage of CD4 circulating lymphocytes and increased spontaneous in vitro immunoglobulin production. These changes were persistent in the HIV-1 infected children, but sporadic in those uninfected. Immunological abnormalities were frequently found before clinical symptoms appeared. We conclude that repeated immunological abnormalities in babies born to HIV-1 seropositive mothers are suggestive of HIV-1 infection.

Prognostic significance of immunologic changes in 675 infants perinatally exposed to human immunodeficiency virus. The Italian Register for Human Immunodeficiency Virus Infection in Children

Neutrophil, lymphocyte, and T-cell subset numbers and immunoglobulin levels were evaluated at birth to age 2 years in 675 children born to mothers infected with the human immunodeficiency virus type 1 (58 infected symptom-free subjects (P-1), 203 infected subjects with symptoms (P-2), and 414 uninfected subjects). The P-2 patients had (even at birth to age 1 month) lower CD4+ lymphocyte and higher IgA and IgM values than P-1 and uninfected children had. Increased IgG values (from 1 to 6 months of age) and increased CD8+ lymphocyte numbers (at 13 to 24 months of age) were also observed. The P-1 children differed from uninfected children only at 13 to 24 months of age (decreased CD4+ and increased CD8+ lymphocytes). Progressive immunologic changes were found in P-2 patients who had severe clinical conditions and in those who died. To evaluate the predictive meaning of the immunologic changes, we selected 164 children (25 P-2, 15 P-1, and 124 uninfected children) because they had been examined sequentially from birth and they were classified as in the indeterminate state of infection (P-0) at immunologic evaluations at birth to age 1 and at 1 to 6 months of age. During the 1- to 6-month period, P-2 patients had higher immunoglobulin and lower CD4+ lymphocyte values than P-1 and uninfected children had; no difference was found between P-1 and uninfected subjects. These results indicate that in infants with perinatal human immunodeficiency virus type 1 infection, immunologic abnormalities correlate with the clinical condition and are predictive of the clinical outcome rather than the infection status.

A hospital-based prospective study of perinatal infection with human immunodeficiency virus type 1

Most infants with pediatric acquired immunodeficiency syndrome and infections with human immunodeficiency virus type 1 (HIV-1) are infected perinatally by their mothers. To determine the proportion of exposed infants who are infected, we conducted a hospital-based prospective study in HIV-1-infected women whose infants were delivered at a single metropolitan hospital in Miami, Fla. A population of uninfected women and their infants was also enrolled and followed longitudinally for 2 years to assess laboratory and clinical measurements. The median follow-up is now 18 months for 82 infants born to HIV-1-infected mothers. The proportion of infected infants in this group is 0.30 (25/82). None of the infants born to 110 HIV-1-seronegative mothers were seropositive. Infected infants were easily distinguished from noninfected infants by virus isolation. No single immunologic or hematologic measure was predictive of infection for all infants at risk for HIV-1 infection who were 6 months of age or younger. As a group, however, infected infants could be distinguished from uninfected index infants by a number of immunologic measures by 6 months of age; the absolute number of CD4+ lymphocytes and the CD4+/CD8+ lymphocyte ratio were the variables most predictive of infection. As in retrospective studies, clinical disease developed in 80% of infected infants within the first 24 months of life. This study provides documentation of HIV-1 perinatal transmission risk and early correlates of infection in young infants from a single hospital.

Repeated polymerase chain reaction complementary to other conventional methods for early detection of HIV infection in infants born to HIV-infected mothers

The efficacy of a polymerase chain reaction (PCR) method for early detection of human immunodeficiency virus (HIV) in infants at risk for HIV infection was assessed. The PCR method was added to the routine laboratory test programme in these patients in 1988. PCR was performed in a total of 26 children at risk (age range 2 days to 58 months), including 17 infants born to HIV-infected mothers, who were followed up clinically from the time of birth for a mean period of 23 months (range 6 to 54) in a prospective study. Twelve children were PCR-positive. Eight had AIDS, ARC or symptoms suggestive of HIV infection. All these patients had at least one culture positive for HIV (6/8) and/or one positive serum p24-antigen test (5/8). One child was repeatedly PCR positive, but asymptomatic as well as virus- and antigen-negative. Three asymptomatic children with a single positive PCR result were PCR negative in subsequent tests. Fourteen children with negative PCR did not show clinical or immunological signs suggestive of HIV infection. Their cultures for HIV and antigen-p24 assays were negative. It is concluded that in addition to clinical and immunological parameters PCR is a useful technique for diagnosis of HIV infection in infants born to HIV-infected mothers. However, in case of negative HIV cultures and/or serum p24-antigen tests, single positive PCR results in asymptomatic patients must be interpreted with caution and should be confirmed by repeated tests.