Minimizing the risk of non-vertical, non-sexual HIV infection in children--beyond mother to child transmission

Horizontal HIV transmission to children of HIV-uninfected mothers: A case series and review of the global literature

BACKGROUND

Vertical transmission is the predominant route for acquisition of HIV infection in children, either in utero, intrapartum or postnatally through breast feeding. Less frequently, children may acquire HIV by horizontal transmission. Horizontal transmission may be healthcare-associated (infusion of HIV-contaminated blood products, use of contaminated needles, syringes and medical equipment, or through ingestion of HIV in expressed breastmilk). Community-acquired HIV transmission to children may occur following surrogate breastfeeding, pre-mastication of food, and sexual abuse.

METHODS

Children with suspected horizontally acquired HIV infection were identified by retrospective folder review of existing patients (2004-2014) and by prospective interview and examination of new patients (from 2009 onwards), at a hospital-based paediatric antiretroviral clinic in Cape Town, South Africa. The global literature on horizontal HIV transmission to children (1 January 1986-1 November 2019) was reviewed, to contextualize the local findings.

RESULTS

Among the 32 children with horizontal HIV transmission (15 identified retrospectively and 17 prospectively), the median age at first diagnosis was 79 months (interquartile range 28.5-91.5); most children (90.6%) had advanced HIV disease at presentation. HIV transmission was considered healthcare-associated in 15 (46.9%), community-associated in ten (31.3%), possibly healthcare or community-associated in five (15.6 %); and unknown in two children (6.3%).

CONCLUSION

Horizontal HIV transmission to children is an important public health issue, with prevention efforts requiring intervention at healthcare facility- and community-level. Greater effort should be made to promptly identify and comprehensively investigate each horizontally HIV-infected child to establish possible routes of transmission and inform future prevention strategies.

Paediatric non-progression following grandmother-to-child HIV transmission

Background

In contrast to adult HIV infection, where slow disease progression is strongly linked to immune control of HIV mediated by protective HLA class I molecules such as HLA-B*81:01, the mechanisms by which a minority of HIV-infected children maintain normal-for-age CD4 counts and remain clinically healthy appear to be HLA class I-independent and are largely unknown. To better understand these mechanisms, we here studied a HIV-infected South African female, who remained a non-progressor throughout childhood.

Results

Phylogenetic analysis of viral sequences in the HIV-infected family members, together with the history of grand-maternal breast-feeding, indicated that, unusually, the non-progressor child had been infected via grandmother-to-child transmission. Although HLA-B*81:01 was expressed by both grandmother and grand-daughter, autologous virus in each subject encoded an escape mutation L188F within the immunodominant HLA-B*81:01-restricted Gag-specific epitope TL9 (TPQDLNTML, Gag 180–188). Since the transmitted virus can influence paediatric and adult HIV disease progression, we investigated the impact of the L188F mutant on replicative capacity. When this variant was introduced into three distinct HIV clones in vitro, viral replicative capacity was abrogated altogether. However, a virus constructed using the gag sequence of the non-progressor child replicated as efficiently as wildtype virus.

Conclusion

These findings suggest alternative sequences of events: the transmission of the uncompensated low fitness L188F to both children, potentially contributing to slow progression in both, consistent with previous studies indicating that disease progression in children can be influenced by the replicative capacity of the transmitted virus; or the transmission of fully compensated virus, and slow progression here principally the result of HLA-independent host-specific factors, yet to be defined.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-016-0300-y) contains supplementary material, which is available to authorized users.