MalE of group A Streptococcus participates in the rapid transport of maltotriose and longer maltodextrins

Study of the maltose/maltodextrin binding protein MalE in Escherichia coli has resulted in fundamental insights into the molecular mechanisms of microbial transport. Whether gram-positive bacteria employ a similar pathway for maltodextrin transport is unclear. The maltodextrin binding protein MalE has previously been shown to be key to the ability of group A Streptococcus (GAS) to colonize the oropharynx, the major site of GAS infection in humans. Here we used a multifaceted approach to elucidate the function and binding characteristics of GAS MalE. We found that GAS MalE is a central part of a highly efficient maltodextrin transport system capable of transporting linear maltodextrins that are up to at least seven glucose molecules long. Of the carbohydrates tested, GAS MalE had the highest affinity for maltotriose, a major breakdown product of starch in the human oropharynx. The thermodynamics and fluorescence changes induced by GAS MalE-maltodextrin binding were essentially opposite those reported for E. coli MalE. Moreover, unlike E. coli MalE, GAS MalE exhibited no specific binding of maltose or cyclic maltodextrins. Our data show that GAS developed a transport system optimized for linear maltodextrins longer than two glucose molecules that has several key differences from its well-studied E. coli counterpart.     

Seasonality of births in South-Eastern Nigeria.

A study of seasonal pattern of births in Nigeria was conducted using data on live births for the period 1971-76 from 4 climatically similar southeastern states (Anambra, Imo, Cross River and Rivers State). After pooling the data, the monthly distribution for different years was calculated. The resulting time series was graphically compared with temperature levels during time of conception, or nine months back. Data analysis revealed a seasonal pattern in the monthly distribution of births, with the peak period observed during April-June, and a trough during November-January. Counting 9 months back, the conceptions were calculated as occuring during July, August, or September of the previous year. In terms of the annual agricultural cycle of the southeastern states, July-September corresponded with the period of light farm work or relative idleness for men (main activity during this period is weeding and tending the crops, tasks primarily done by women and children); this is also a period of abundance of fruits, vegetables and palm wine, and rains after dusk, conditions conducive to mating.     

Conditional economic incentives and motivational interviewing to improve adolescents’ retention in HIV care and adherence to antiretroviral therapy in Southeast Nigeria: study protocol for a cluster randomised trial

Background

Adolescent HIV patients face enormous difficulty in accessing HIV care services. Given their vulnerability to risk-taking behaviour, this group also have worse treatment outcomes compared to other age groups. Poor treatment outcomes will impact negatively on HIV/AIDS management and control particularly in sub-Saharan Africa (SSA) as more than eight out of ten of the world’s HIV-infected adolescents live in this region of the world. Limited evidence exists on the effectiveness of service delivery interventions to support adolescents’ retention on antiretroviral therapy (ART) and adherence to ART. This trial is designed to evaluate the impact of conditional economic incentive and motivational interviewing on adolescents’ retention in HIV care and adherence to ART in Anambra State, Southeast Nigeria.

Methods/design

The study will be a cluster randomised controlled trial that will be conducted in selected HIV treatment hospitals in Anambra State, Nigeria. Based on sample size calculation, 12 HIV treatment hospitals from Anambra will be selected for the study. Six HIV treatment hospitals each will be randomised to either the intervention or the control arm. A structured adherence support scheme termed the ‘Incentive Scheme’ will be applied to the intervention arm while the control arm will receive routine HIV care (usual care). Additionally, patients in the intervention arm will receive motivational interviewing at baseline and following initiation of antiretroviral therapy (ART), they will receive a gift voucher of US$5.6 when HIV viral load (VL) is <?20 copies/mL at 12?weeks, a gift voucher of US$2.8 if the VL remains suppressed for the next 3?months, and the next 6?months, and finally a gift voucher of US$5.6 if the VL remains <?20 copies/mL at 1?year. All gift vouchers will be conditional not only on VL results but attending the motivational interviews. The primary outcome for the trial will be the difference between groups in the proportion with HIV VL suppression (≤?20 copies/mL) by 12?months and then 24?months after withdrawal of incentive.

Discussion

The findings of this proposed trial will provide evidence on the feasibility of applying conditional economic incentives combined with motivational interviewing to improve retention and adherence to antiretroviral therapy of adolescents living with HIV in Nigeria and possibly in other sub-Saharan African countries.

Trial registration

Registered in the Pan African Clinical Trials Registry, ID: PACTR201806003040425. Registered on 2 February 2018.