Dynamics of immunoglobulin G subclasses during the first two years of life in Malawian infants born to HIV-positive mothers

Screening approaches for cervical cancer in Mozambique in HIV positive and negative women

OBJECTIVE

Cervical cancer (CC) is a global health issue, in Mozambique, 5300 new cases and 3800 deaths are reported each year. The WHO recommends the introduction of HPV molecular testing for CC screening, but Mozambique uses an approach based on visual inspection with acetic acid (VIA). This study aims to evaluate the feasibility of high-risk HPV (hrHPV) testing compared to actual approaches in Mozambique.

METHODS

An observational study was carried out in the DREAM center in Zimpeto, Mozambique. Women aged 30-55 were included. HPV testing was performed with the Cobas HPV test. They were then screened with the current national recommendations based on VIA. Cryotherapy was performed on-site or referred for colposcopy if necessary.

RESULTS

In the period, 1207 women were enrolled, 47.8% HIV+; 124 (10.3%) VIA+, and HPV DNA test was positive in 325 (26.9%) women. HPV positivity rates were higher in HIV-infected women. In the sample, 52.8% of the 124 VIA+ women were HPV uninfected and underwent unnecessary cryotherapy or colposcopy. Meanwhile, 24.7% of the 1083 VIA- women were actually HPV infected. In comparison, a screen, triage and treat approach based on hrHPV testing would only test and treat the 325 HPV-infected women.

CONCLUSION

The study found high rates of hrHPV infection, particularly in HIV-positive women, with many concurrent or multiple infections. The current screening method misses important hrHPV infections and results in many unnecessary treatments. These results support the use of HPV molecular testing as the initial screening test for CC.

Fc receptor engagement of HIV-1 Env-specific antibodies in mothers and infants predicts reduced vertical transmission

Introduction

Infants acquire maternal antibodies by Fc receptor transcytosis across the placenta during pregnancy. Fc receptors are expressed on immune cells and are important for activation of effector cell functions.

Methods

In this study, we evaluated Fc receptor engagement and ADCC activity of plasma binding antibodies from human immunodeficiency virus-1 (HIV) -infected mothers and to identify factors that may contribute to protection from HIV vertical transmission.

Results

HIV-specific binding and Fc receptor engagement of plasma antibodies varied between mothers by transmission status and infants by infection status. Non-transmitting (NT) mothers and HIV-uninfected infants had antibodies with higher neonatal Fc receptor (FcRn) and FcγR engagement, as compared to transmitting (T) mothers and HIV+ infants, respectively. A significant inverse correlation between plasma antibody FcRn and FcγR engagement was observed for T mothers, but not NT mothers. Conversely, a significant direct correlation was observed between plasma antibody FcRn and FcγR engagement for HIV- infants, but not for HIV+ infants. Consequently, we observed significantly higher plasma antibody ADCC potency and breadth in HIV- infants, as compared to HIV+ infants. However, no differences in overall ADCC potency and breadth were observed between mothers. FcRn-engagement of HIV-specific antibodies in both mothers and infants predicted a lack of vertical transmission of HIV.

Discussion

This study indicates that HIV-uninfected infants acquire HIV-specific antibodies with greater Fc receptor engagement and thus, greater ADCC capacity.

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.

Delays in HIV-1 infant polymerase chain reaction testing may leave children without confirmed diagnoses in the Western Cape province, South Africa

Background

Early diagnosis and confirmation of HIV infection in newborns is crucial for expedited initiation of antiretroviral therapy. Confirmatory testing must be done for all children with a reactive HIV PCR result. There is no comprehensive data on confirmatory testing and HIV PCR test request rejections at National Health Laboratory Service laboratories in South Africa.

Objective

This study assessed the metrics of routine infant HIV PCR testing at the Tygerberg Hospital Virology Laboratory, Cape Town, Western Cape, South Africa, including the proportion of rejected test requests, turn-around time (TAT), and rate of confirmatory testing.

Methods

We retrospectively reviewed laboratory-based data on all HIV PCR tests performed on children ≤ 24 months old (n = 43 346) and data on rejected HIV PCR requests (n = 1479) at the Tygerberg virology laboratory over two years (2017–2019). Data from sample collection to release of results were analysed to assess the TAT and follow-up patterns.

Results

The proportion of rejected HIV PCR requests was 3.3%; 83.9% of these were rejected for various pre-analytical reasons. Most of the test results (89.2%) met the required 96-h TAT. Of the reactive initial test results, 53.5% had a follow-up sample tested, of which 93.1% were positive. Of the initial indeterminate results, 74.7% were negative on follow-up testing.

Conclusion

A high proportion of HIV PCR requests were rejected for pre-analytical reasons. The high number of initial reactive tests without evidence of follow-up suggests that a shorter TAT is required to allow confirmatory testing before children are discharged.

Immunoglobulin G passive transfer from mothers to infants: total IgG, IgG subclasses and specific antipneumococcal IgG in 6-week Malawian infants exposed or unexposed to HIV

Background

The impaired transplacental passage of IgG from mothers living with HIV to their infants could be one of the causes of the high vulnerability to infections of HIV-exposed uninfected (HEU) infants, but controversial results have been obtained in different settings. The aim of this study was to assess in 6-week old HEU and HIV-unexposed, uninfected (HUU) Malawian infants the total IgG levels, the subclasses profile and the concentrations of global anti-pneumococcal capsular polysaccharide (anti-PCP) IgG and IgG2.

Methods

Dried blood spots were collected from 80 infants (40 HEU, 40 HUU) and antibodies concentrations determined by nephelometric method (total IgG and subclasses), or using ELISA (anti-PCP total IgG and IgG2). Results are expressed as median levels with IQR, while the proportions of each subclass out of the total IgG are used to describe the subclasses profile.

Results

At 6 weeks HEU infants had higher median levels of total IgG and IgG1 and a significantly lower level of IgG2 [0.376 (0.344–0.523) g/l vs 0.485 (0.374–0.781) g/l, p = 0.037] compared to the HUU counterparts. The IgG subclasses distribution confirmed the underrepresentation of IgG2 (IgG2 represented 5.82% of total IgG in HEU and 8.87% in HUU). The anti-PCP IgG and IgG2 levels were significantly lower in HEU infants [8.9 (5.4–15.1) mg/l vs 16.2 (9.61–25.8) mg/l in HUU, p < 0.001, and 2.69 (1.90–4.29) mg/l vs 4.47 (2.96–5.71) mg/l in HUU, p = 0.001, respectively].

Conclusion

Compared to HUU infants, HEU infants have IgG abnormalities mainly represented by low IgG2 levels, suggesting that despite maternal antiretroviral therapy, the mechanisms of IgG transplacental passage continue to be impaired in women living with HIV. HEU infants also showed a significantly lower level of specific anti-PCP IgG, possibly favouring a high vulnerability to S. pneumoniae infection at an age when protection is mostly depending on maternal IgG.

Are HIV-1-Specific Antibody Levels Potentially Useful Laboratory Markers to Estimate HIV Reservoir Size? A Review

Despite the benefits achieved by the widespread availability of modern antiretroviral therapy (ART), HIV RNA integration into the host cell genome is responsible for the creation of latent HIV reservoirs, and represents a significant impediment to completely eliminating HIV infection in a patient via modern ART alone. Several methods to measure HIV reservoir size exist; however, simpler, cheaper, and faster tools are required in the quest for total HIV cure. Over the past few years, measurement of HIV-specific antibodies has evolved into a promising option for measuring HIV reservoir size, as they can be measured via simple, well-known techniques such as the western blot and enzyme-linked immunosorbent assay (ELISA). In this article, we re-visit the dynamic evolution of HIV-1-specific antibodies and the factors that may influence their levels in the circulation of HIV-positive individuals. Then, we describe the currently-known relationship between HIV-1-specific antibodies and HIV reservoir size based on study of data from contemporary literature published during the past 5 years. We conclude by highlighting current trends, and discussing the individual HIV-specific antibody that is likely to be the most reliable antibody for potential future utilization for quantification of HIV reservoir size.