Cytomegalovirus viraemia is associated with poor growth and T-cell activation with an increased burden in HIV-exposed uninfected infants

Cytomegalovirus viremia in HIV-exposed and HIV-unexposed infants in Malawi

In sub-Saharan Africa the great majority of infants acquire Cytomegalovirus (CMV) infection within the first year of life. Maternal long-term antiretroviral therapy (ART) has been suggested to reduce the rate of CMV acquisition in HIV-exposed infants. In the present study serum samples collected at 6 months of age from HIV-exposed and HIV-unexposed infants were analyzed for the presence of CMV DNA (with CMV positivity defined by levels of CMV DNA > 1000 UI/ml). Twenty out of 58 (34.5%) infants had CMV DNA > 1000 UI/ml. There was no difference in the prevalence of CMV viremia between HIV-exposed and -unexposed infants [33.3% (15/45) vs 38.5% (5/13), respectively, P = 0.488]. In the HIV-exposed group, mothers of CMV-negative infants had received a longer antiretroviral treatment before delivery in comparison to mothers of CMV-positive infants (28 vs 3 months, P = 0.187). No differences in weights and lengths at birth, and at 1, 6 and 12 months were observed between CMV-positive and CMV-negative infants. In this study, the prevalence of CMV viremia at six months of age was high in infants born to HIV-positive mothers receiving long-term ART, similar to that of HIV-unexposed infants. Considering the possible relevant impact of CMV on infant health, strategies for containment of the infection should be explored.

Neurodevelopment among children exposed to HIV and uninfected in sub-Saharan Africa

INTRODUCTION

The population of 16 million children exposed to HIV and uninfected (CHEU) under 15 years of age continues to expand rapidly, and the estimated prevalence of CHEU exceeds 20% in several countries in sub-Saharan Africa with high HIV prevalence. Some evidence suggests that CHEU experience suboptimal neurodevelopmental outcomes compared to children born to women without HIV. In this commentary, we discuss the latest research on biologic and socio-behavioural factors associated with neurodevelopmental outcomes among CHEU.

DISCUSSION

Some but not all studies have noted that CHEU are at risk of poorer neurodevelopment across multiple cognitive domains, most notably in language and motor skills, in diverse settings, ages and using varied assessment tools. Foetal HIV exposure can adversely influence infant immune function, structural brain integrity and growth trajectories. Foetal exposure to antiretrovirals may also influence outcomes. Moreover, general, non-CHEU-specific risk factors for poor neurodevelopment, such as preterm birth, food insecurity, growth faltering and household violence, are amplified among CHEU; addressing these factors will require multi-factorial solutions. There is a need for rigorous harmonised approaches to identify children at the highest risk of delay. In high-burden HIV settings, existing maternal child health programmes serving the general population could adopt structured early child development programmes that educate healthcare workers on CHEU-specific risk factors and train them to conduct rapid neurodevelopmental screening tests. Community-based interventions targeting parent knowledge of optimal caregiving practices have shown to be successful in improving neurodevelopmental outcomes in children and should be adapted for CHEU.

CONCLUSIONS

CHEU in sub-Saharan Africa have biologic and socio-behavioural factors that may influence their neurodevelopment, brain maturation, immune system and overall health and wellbeing. Multidisciplinary research is needed to disentangle complex interactions between contributing factors. Common environmental and social risk factors for suboptimal neurodevelopment in the general population are disproportionately magnified within the CHEU population, and it is, therefore, important to draw on existing knowledge when considering the socio-behavioural pathways through which HIV exposure could impact CHEU neurodevelopment. Approaches to identify children at greatest risk for poor outcomes and multisectoral interventions are needed to ensure optimal outcomes for CHEU in sub-Saharan Africa.

Indirect effects of cytomegalovirus infection: Implications for vaccine development

Development of a cytomegalovirus (CMV) vaccine is a high priority due to its significant global impact-contributing to mortality in immunosuppressed individuals, neurodevelopmental delay in infected neonates and non-genetic sensorineural hearing loss. The impact of CMV on the general population has been less well studied; however, a wide range of evidence indicates that CMV may increase the risk of atherosclerosis, cancer, immunosenescence, and progression of tuberculosis (TB) and human immunodeficiency virus. Due to the high seroprevalence of CMV worldwide, any modulation of risk by CMV is likely to have a significant impact on the epidemiology of these diseases. This review will evaluate how CMV may cause morbidity and mortality outside of the neonatal and immunosuppressed populations and consider the potential impact of a CMV vaccine on these outcomes.

Defective Monocyte Enzymatic Function and an Inhibitory Immune Phenotype in Human Immunodeficiency Virus-Exposed Uninfected African Infants in the Era of Antiretroviral Therapy

BACKGROUND

Human immunodeficiency virus-exposed uninfected (HEU) infants are a rapidly expanding population in sub-Saharan Africa and are highly susceptible to encapsulated bacterial disease in the first year of life. The mechanism of this increased risk is still poorly understood. We investigated whether human immunodeficiency virus (HIV)-exposure dysregulates HEU immunity, vaccine-antibody production, and human herpes virus amplify this effect.

METHODS

Thirty-four HIV-infected and 44 HIV-uninfected pregnant women were recruited into the birth cohort and observed up to 6 weeks of age; and then a subsequent 43 HIV-infected and 61 HIV-uninfected mother-infant pairs were recruited into a longitudinal infant cohort at either: 5-7 to 14-15; or 14-15 to 18-23 weeks of age. We compared monocyte function, innate and adaptive immune cell phenotype, and vaccine-induced antibody responses between HEU and HIV-unexposed uninfected (HU) infants.

RESULTS

We demonstrate (1) altered monocyte phagosomal function and B-cell subset homeostasis and (2) lower vaccine-induced anti-Haemophilus influenzae type b (Hib) and anti-tetanus toxoid immunoglobulin G titers in HEU compared with HU infants. Human herpes virus infection was similar between HEU and HU infants.

CONCLUSIONS

In the era of antiretroviral therapy-mediated viral suppression, HIV exposure may dysregulate monocyte and B-cell function, during the vulnerable period of immune maturation. This may contribute to the high rates of invasive bacterial disease and pneumonia in HEU infants.

Complexity of Human Cytomegalovirus Infection in South African HIV-Exposed Infants with Pneumonia

Human cytomegalovirus (HCMV) can cause significant end-organ diseases such as pneumonia in HIV-exposed infants. Complex viral factors may influence pathogenesis including: a large genome with a sizeable coding capacity, numerous gene regions of hypervariability, multiple-strain infections, and tissue compartmentalization of strains. We used a whole genome sequencing approach to assess the complexity of infection by comparing high-throughput sequencing data obtained from respiratory and blood specimens of HIV-exposed infants with severe HCMV pneumonia with those of lung transplant recipients and patients with hematological disorders. There were significantly more specimens from HIV-exposed infants showing multiple HCMV strain infection. Some genotypes, such as UL73 G4B and UL74 G4, were significantly more prevalent in HIV-exposed infants with severe HCMV pneumonia. Some genotypes were predominant in the respiratory specimens of several patients. However, the predominance was not statistically significant, precluding firm conclusions on anatomical compartmentalization in the lung.

Cytomegalovirus viremia and clinical outcomes in Kenyan children diagnosed with HIV in hospital

BACKGROUND

Cytomegalovirus (CMV) viremia is common in HIV infection, and is associated with worse long-term outcomes. To date, no studies have assessed CMV viremia in children diagnosed with HIV in hospital.

METHODS

We studied CMV viremia and clinical outcomes in 163 Kenyan children aged 2 months-12 years, diagnosed with HIV in hospital. CMV DNA levels in plasma were measured using quantitative PCR. Regression models were used to assess associations between CMV viremia >1000 IU/mL and the risk of continued hospitalization or death at 15 days, duration of hospitalization, and 6-month mortality.

RESULTS

At enrollment, 62/114 (54%) children had CMV viremia, and 20 (32%) were >1000 IU/mL. Eleven CMV reactivations were observed after admission. The prevalence and level of CMV viremia were highest in children <2 years and lowest in children >5 years old. CMV viremia >1000 IU/mL was independently associated with age < 2 years (p=0.03), higher log10 HIV RNA level (p=0.01), and height-for-age z score <-2 (p=0.02). Adjusting for age and log10 HIV RNA, the relative risk of death or continued hospitalization at 15 days was 1.74 (95%CI=1.04, 2.90), and the hazard ratio of 6-month mortality was 1.97 (95%CI=0.57, 5.07) for children with CMV DNA ≥1000 IU/ml compared to lower-level or undetectable CMV DNA. Children with CMV DNA ≥1000 IU/ml were hospitalized a median ~5 days longer than children with lower-level or undetectable CMV DNA (p=0.002).

CONCLUSIONS

In this nested observational study, CMV viremia was common in hospitalized children with HIV, and levels ≥1000 IU/mL were associated with increased risk of mortality and longer hospitalization.

Growth Trajectories of HIV Exposed and HIV Unexposed Infants. A Prospective Study in Gweru, Zimbabwe

Background

With the increasing HIV seroprevalence among women of childbearing age in sub-Saharan Africa, limited data on growth outcomes of HIV exposed infants under current policies of universal maternal antiretroviral therapy exist.

Methods

The longitudinal growth patterns of 114 HIV exposed and unexposed infants were assessed and compared. The prevalence and factors associated with malnutrition were established. Infants under prevention of mother to child transmission care were recruited at 6 weeks post-delivery as were their HIV unexposed counterparts. Weight and length measurements were recorded at birth, 6 and 16 weeks postpartum.

Results

HIV vertical transmission rate was 8.8%. HIV exposed infants had significantly lower mean birth weights compared to HIV unexposed infants (2.9 ± 0.3; 3.2 ± 0.5; P < .001) respectively. Mean weight/length-for-age z-scores for HIV exposed, uninfected (HEU) infants were significantly below those of the HIV unexposed infants during follow up. By 6 weeks of age, 28.5% of HEU infants were malnourished while no malnutrition was evident in HIV unexposed infants. A gestational age <37 weeks (OR: 3.83; 95% CI: 1.03-14.30; P = .045) and HIV exposure (OR: 1.62; 95% CI: 0.17-15.73; P = .017) substantially increased the risk of stunting.

Conclusion

Growth deficits were witnessed in HIV exposed infants compared to HIV unexposed infants. There is need for early nutritional monitoring and support among HIV exposed infants.

Mixed cytomegalovirus genotypes in HIV-positive mothers show compartmentalization and distinct patterns of transmission to infants

Cytomegalovirus (CMV) is the commonest cause of congenital infection and particularly so among infants born to HIV-infected women. Studies of congenital CMV infection (cCMVi) pathogenesis are complicated by the presence of multiple infecting maternal CMV strains, especially in HIV-positive women, and the large, recombinant CMV genome. Using newly developed tools to reconstruct CMV haplotypes, we demonstrate anatomic CMV compartmentalization in five HIV-infected mothers and identify the possibility of congenitally transmitted genotypes in three of their infants. A single CMV strain was transmitted in each congenitally infected case, and all were closely related to those that predominate in the cognate maternal cervix. Compared to non-transmitted strains, these congenitally transmitted CMV strains showed statistically significant similarities in 19 genes associated with tissue tropism and immunomodulation. In all infants, incident superinfections with distinct strains from breast milk were captured during follow-up. The results represent potentially important new insights into the virologic determinants of early CMV infection.

Association Between Cytomegalovirus and Epstein-Barr Virus Viremia And Human Immunodeficiency Virus DNA Levels in the Reservoir of Kenyan Infants Receiving Antiretroviral Therapy

Identifying determinants of human immunodeficiency virus (HIV) reservoir levels may inform novel viral eradication strategies. Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) coinfections were assessed as predictors of HIV proviral DNA level in 26 HIV RNA-suppressed Kenyan children starting antiretroviral therapy before 7 months of age. Earlier acquisition of CMV and EBV and higher cumulative burden of systemic EBV DNA viremia were each associated with higher HIV DNA level in the reservoir after 24 months of antiretroviral therapy, independent of HIV RNA levels over time. These data suggest that delaying or containing CMV and EBV viremia may be novel strategies to limit HIV reservoir formation.

The University of Zimbabwe College of Health Sciences (UZ-CHS) BIRTH COHORT study: rationale, design and methods

BACKGROUND

Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+), has greatly improved maternal-infant health. Thus, large and increasing numbers of HIV-infected women are on ART during pregnancy, a situation concurrently increasing numbers of HIV-exposed-uninfected (HEU) infants. Compared to their HIV-unexposed-uninfected (HUU) counterparts, HEU infants show higher rates of adverse birth outcomes, mortality, infectious/non-communicable diseases including impaired growth and neurocognitive development. There is an urgent need to understand the impact of HIV and early life ART exposures, immune-metabolic dysregulation, comorbidities and environmental confounders on adverse paediatric outcomes.

METHODS

Six hundred (600) HIV-infected and 600 HIV-uninfected pregnant women ≥20 weeks of gestation will be enrolled from four primary health centres in high density residential areas of Harare. Participants will be followed up as mother-infant-pairs at delivery, week(s) 1, 6, 10, 14, 24, 36, 48, 72 and 96 after birth. Clinical, socio-economic, nutritional and environmental data will be assessed for adverse birth outcomes, impaired growth, immune/neurodevelopment, vertical transmission of HIV, hepatitis-B/C viruses, cytomegalovirus and syphilis. Maternal urine, stool, plasma, cord blood, amniotic fluid, placenta and milk including infant plasma, dried blood spot and stool will be collected at enrolment and follow-up visits. The composite primary endpoint is stillbirth and infant mortality within the first two years of life in HEU versus HUU infants. Maternal mortality in HIV-infected versus -uninfected women is another primary outcome. Secondary endpoints include a range of maternal and infant outcomes. Sub-studies will address maternal stress and malnutrition, maternal-infant latent tuberculosis, Helicobacter pylori infections, immune-metabolomic dysregulation including gut, breast milk and amniotic fluid dysbiosis.

DISCUSSION

The University of Zimbabwe-College of Health-Sciences-Birth-Cohort study will provide a comprehensive assessment of risk factors and biomarkers for HEU infants' adverse outcomes. This will ultimately help developing strategies to mitigate effects of maternal HIV, early-life ART exposures and comorbidities on infants' mortality and morbidity.

TRIAL REGISTRATION

ClinicalTrial.gov Identifier: NCT04087239 . Registered 12 September 2019.

Child HIV Exposure and CMV Seroprevalence in Botswana: No Associations With 24-Month Growth and Neurodevelopment

Background

We sought to identify predictors of child cytomegalovirus (CMV) infection overall and by maternal HIV status and to assess associations of child CMV status with growth and neurodevelopmental outcomes at 24 months of age in Botswana.

Methods

Data and samples were used from the Botswana-based observational Tshipidi study (2010–2014), enrolling pregnant women living with and without HIV and following their infants through 2 years of age. Child plasma samples were tested at 18 months of age for anti-CMV immunoglobulin G (IgG). Associations were assessed between detectable anti-CMV IgG and growth (using the World Health Organization Child Growth Standards) and neurodevelopment (using the Bayley Scales of Infant and Toddler Development III and the Developmental Milestones Checklist) at 24 months of age.

Results

Of 317 children, 215 (68%) had detectable anti-CMV IgG at 18 months of age. Comparatively, 83% (n = 178) of HIV-unexposed uninfected (HUU) children had positive CMV serology vs 47% (n = 139) of HIV-exposed uninfected (HEU) children (P < .01); 100% of HUU vs 10.5% of HEU children breastfed. Child CMV infection was not associated with weight-for-age, weight-for-length, or length-for-age z-scores at 24 months. In HUU children, CMV infection was associated with smaller head circumference (P < .01). No difference was observed by child CMV status in any neurodevelopmental domain at 24 months.

Conclusions

We observed high CMV seropositivity in 18-month-old children in Botswana, with higher seropositivity among breastfed (HUU) children. Positive CMV serostatus was not associated with 24-month child growth or neurodevelopmental outcomes, with the exception of smaller head circumference among HUU CMV-positive children.

Human Immunodeficiency Virus Exposure but Not Early Cytomegalovirus Infection Is Associated With Increased Hospitalization and Decreased Memory T-Cell Responses to Tetanus Vaccine

BACKGROUND

Human immunodeficiency virus (HIV)-exposed, uninfected (HEU) infants experience high rates of infectious morbidity. We hypothesized that early cytomegalovirus (CMV) infection was associated with increased hospitalization rates and decreased vaccine responses in HEU compared with HIV-unexposed (HUU) infants.

METHODS

Among infants enrolled in the Tshipidi study in Botswana, we determined CMV infection status by 6 months of age and compared hospitalization rates and responses to tetanus and Bacille Calmette-Guérin vaccines among HEU and HUU vaccinees.

RESULTS

Fifteen of 226 (6.6%) HEU infants and 17 (19.3%) of 88 HUU infants were CMV-infected by 6 months. The HEU infants were approximately 3 times as likely to be hospitalized compared with HUU infants (P = .02). The HEU peripheral blood cells produced less interleukin (IL)-2 (P = .004), but similar amounts of interferon-γ, after stimulation with tetanus toxoid. Antitetanus immunoglobulin G titers were similar between groups. Cellular responses to purified protein derivative stimulation did not differ between groups. Maternal receipt of 3-drug antiretroviral therapy compared with zidovudine was associated with increased IL-2 expression after tetanus toxoid stimulation. The infants' CMV infection status was not associated with clinical or vaccine response outcomes.

CONCLUSIONS

We observed that increased rates of hospitalization and decreased memory T-cell responses to tetanus vaccine were associated with HIV exposure and incomplete treatment of maternal HIV infection, but not early CMV infection.

Growth and Neurodevelopment of HIV-Exposed Uninfected Children: a Conceptual Framework

PURPOSE OF REVIEW

The population of HIV-exposed uninfected (HEU) children is expanding rapidly, and over one million HEU infants are born each year globally. Several recent studies have reported that HEU children, particularly in low- and middle-income countries, are at risk of poor outcomes, including impaired growth and neurodevelopment. However, the reasons for poor clinical outcomes amongst HEU children remain unclear.

RECENT FINDINGS

We summarise the findings from recent large studies that have characterised growth and neurodevelopment in HEU children, identified risk factors and explored underlying mechanistic pathways. We propose a conceptual framework to explain how exposure to HIV and antiretroviral therapy (ART) may lead to adverse growth and neurodevelopment in uninfected children, and review the available evidence and research gaps. We propose that HEU children are affected both indirectly, through the augmentation of universal risk factors underlying poor growth and neurodevelopment, and directly through HIV/ART-specific pathways, which ultimately may converge through a series of common pathogenic mechanisms. In the era of universal ART, a better understanding of these pathways is crucial to inform future prevention and intervention strategies.

Human Cytomegalovirus Enhances Placental Susceptibility and Replication of Human Immunodeficiency Virus Type 1 (HIV-1), Which May Facilitate In Utero HIV-1 Transmission

Several co-pathogens that pose threats to the fetus during gestation, including human cytomegalovirus (HCMV), may also contribute to mother-to-child transmission (MTCT) of human immunodeficiency virus type 1 (HIV-1). Within endemic settings, associations between maternal HCMV viral load and increased incidence of MTCT of HIV-1 are documented; however, the mechanisms that promote transmission are poorly characterized. Here we demonstrate that HCMV coinfection enhances susceptibility and viral replication of HIV-1 in placental macrophages (Hofbauer cells) in vitro. Consistent with enhanced viral susceptibility, HCMV exposure upregulates CCR5 and CD80 expression on Hofbauer cells. HCMV also significantly induces type I interferon (IFN), proinflammatory cytokines, and antiviral gene expression. Interestingly, we found that HCMV diminishes type I IFN-mediated phosphorylation of STAT2. Collectively, our data suggest that HCMV-induced activation, local inflammation, and antagonism of type I IFN responses in placental Hofbauer cells promote in utero transmission of HIV-1.

The convergent epidemiology of tuberculosis and human cytomegalovirus infection

Although several factors are known to increase the risk of tuberculosis, the occurrence of tuberculosis disease in an infected individual is difficult to predict. We hypothesize that active human cytomegalovirus infection due to recent infection, reinfection or reactivation plays an epidemiologically relevant role in the aetiology of tuberculosis by precipitating the progression from latent tuberculosis infection to disease. The most compelling support for this hypothesis comes from the striking similarity in age-sex distribution between the two infections, important because the age-sex pattern of tuberculosis disease progression has not been convincingly explained. Cytomegalovirus infection and tuberculosis have other overlapping risk factors, including poor socio-economic status, solid organ transplantation and, possibly, sexual contact and whole blood transfusion. Although each of these overlaps could be explained by shared underlying risk factors, none of the epidemiological observations refute the hypothesis. If this interaction would play an epidemiologically important role, important opportunities would arise for novel approaches to controlling tuberculosis.

The convergent epidemiology of tuberculosis and human cytomegalovirus infection

Although several factors are known to increase the risk of tuberculosis, the occurrence of tuberculosis disease in an infected individual is difficult to predict. We hypothesize that active human cytomegalovirus infection due to recent infection, reinfection or reactivation plays an epidemiologically relevant role in the aetiology of tuberculosis by precipitating the progression from latent tuberculosis infection to disease. The most compelling support for this hypothesis comes from the striking similarity in age-sex distribution between the two infections, important because the age-sex pattern of tuberculosis disease progression has not been convincingly explained. Cytomegalovirus infection and tuberculosis have other overlapping risk factors, including poor socio-economic status, sexual contact, whole blood transfusion and solid organ transplantation. Although each of these overlaps could be explained by shared underlying risk factors, none of the epidemiological observations refute the hypothesis. If this interaction would play an epidemiologically important role, important opportunities would arise for novel approaches to controlling tuberculosis.

The Effect of Human Immunodeficiency Virus and Cytomegalovirus Infection on Infant Responses to Vaccines: A Review

The success of prevention of mother to child transmission programs over the last two decades has led to an increasing number of infants who are exposed to human immunodeficiency virus (HIV), but who are not themselves infected (HIV-exposed, uninfected infants). Although the morbidity and mortality among HIV-exposed, uninfected infants is considerably lower than that among HIV-infected infants, they may remain at increased risk of infections in the first 2 years of life compared with their HIV-unexposed peers, especially in the absence of breastfeeding. There is some evidence of immunological differences in HIV-exposed, uninfected infants, which could play a role in susceptibility to infection. Cytomegalovirus (CMV) may contribute to the increased immune activation observed in HIV-exposed, uninfected infants. Infants born to HIV-infected women are at increased risk of congenital CMV infection, as well as early acquisition of postnatal CMV infection. In infants with HIV infection, CMV co-infection in early life is associated with higher morbidity and mortality. This review considers how HIV infection, HIV exposure, and CMV infection affect infant responses to vaccination, and explores possible immunological and other explanations for these findings. HIV-infected infants have lower vaccine-induced antibody concentrations following tetanus, diphtheria, pertussis, hepatitis B, and pneumococcal vaccination, although the clinical relevance of this difference is not known. Despite lower concentrations of maternal-specific antibody at birth, HIV-exposed, uninfected infants respond to vaccination at least as well as their HIV-unexposed uninfected peers. CMV infection leads to an increase in activation and differentiation of the whole T-cell population, but there is limited data on the effects of CMV infection on infant vaccine responses. In light of growing evidence of poor clinical outcomes associated with CMV infection in HIV-exposed, uninfected infants, further studies are particularly important in this group. A clearer understanding of the mechanisms by which maternal viral infections influence the developing infant immune system is critical to the success of maternal and infant vaccination strategies.