Access to prevention of mother-to-child transmission of HIV along HIV services cascade through integrated active case management in 15 operational districts in Cambodia

INTRODUCTION

Following the introduction of option B+ in 2013, and with the perspective of eliminating mother-to-child transmission of HIV by 2025, Cambodia has implemented an integrated active case management (IACM) approach since 2014 to improve the notification and follow-up of all HIV-infected cases including pregnant women, and to ensure access to and use of the full prevention of mother-to-child transmission (PMTCT) service package by HIV-infected pregnant women and their HIV-exposed infants. This study aimed to analyse PMTCT cascade data in 15 operational districts (ODs) implementing the IACM approach in Cambodia.

METHODS

We analysed PMTCT cohort data from 15 ODs implementing IACM approach between 1 January 2014 and 31 December 2016. We measured key indicators along the PMTCT cascade and compared them to available (cross-sectional) PMTCT indicators during the 2011 to 2013 period.

RESULTS

During the period 2014 to 2016, among 938 identified HIV-infected pregnant women, 308 (32.8%) were tested HIV positive during their pregnancy, 9 (1.0%) during labour, while the remaining 621 (66.2%) were women on antiretroviral therapy (ART) who became pregnant. During the study period, 867 (92.4%) of the 938 women received ART during pregnancy and labour. Subsequently, 456 (85.6%) of the 533 HEI born and alive during the study period received 6-week antiretroviral (ARV) prophylaxis, 390 (76.6%) and 396 (77.8%) of the 509 infants aged six weeks or older received cotrimoxazole prophylaxis and HIV-DNA PCR test respectively. Among the 396 HEI who received HIV-DNA PCR test, 7 (1.8%) were found HIV positive. The comparison with cross-sectional PMTCT indicator obtained during the previous 2011 to 2013 period in the same 15 ODs, showed a significant increase in ARV uptake among HIV-infected pregnant women (from 72.3% to 92.4%), in cotrimoxazole uptake (from 41.6% to 73.2%), and in HIV-DNA PCR testing coverage among HEI (from 41.2% to 74.3%).

CONCLUSIONS

The implementation of option B+ and IACM may have contributed to the improvement of the PMTCT cascade in Cambodia. However, some gaps in accessing PMTCT services along the HIV cascade persist and need to be addressed.

Towards a Best Practice Approach in PBPK Modeling: Case Example of Developing a Unified Efavirenz Model Accounting for Induction of CYPs 3A4 and 2B6

In this study, we present efavirenz physiologically based pharmacokinetic (PBPK) model development as an example of our best practice approach that uses a stepwise approach to verify the different components of the model. First, a PBPK model for efavirenz incorporating in vitro and clinical pharmacokinetic (PK) data was developed to predict exposure following multiple dosing (600 mg q.d.). Alfentanil i.v. and p.o. drug‐drug interaction (DDI) studies were utilized to evaluate and refine the CYP3A4 induction component in the liver and gut. Next, independent DDI studies with substrates of CYP3A4 (maraviroc, atazanavir, and clarithromycin) and CYP2B6 (bupropion) verified the induction components of the model (area under the curve [AUC] ratios within 1.0–1.7‐fold of observed). Finally, the model was refined to incorporate the fractional contribution of enzymes, including CYP2B6, propagating autoinduction into the model (Racc 1.7 vs. 1.7 observed). This validated mechanistic model can now be applied in clinical pharmacology studies to prospectively assess both the victim and perpetrator DDI potential of efavirenz.

The PsaD subunit of photosystem I. Mutations in the basic domain reduce the level of PsaD in the membranes

The PsaD subunit of photosystem I (PSI) is a peripheral protein that provides a docking site for ferredoxin and interacts with the PsaB, PsaC, and PsaL subunits of PSI. We used site-directed mutagenesis to determine the function of a basic region in PsaD of the cyanobacterium Synechocystis sp. PCC 6803. We generated five mutant strains in which one or more charged residues were altered. Western blotting showed that replacement of lysine (Lys)-74 with glutamine or glutamic acid led to a substantial decrease in the level of PsaD in the membranes. The mutant PSI complexes showed reduced NADP+ photoreduction activity mediated by ferredoxin; the decrease in activity correlated with the reduced level of PsaD. Using protein synthesis inhibitors we showed that the degradation rates of the mutant and wild-type PsaD were similar, indicating a defect in the assembly of the mutant protein. Treatment of the mutant PSI complexes with a different concentration of NaI showed that the mutations decreased affinity between PsaD and the transmembrane components of PSI. With glutaraldehyde, the mutant and wild-type PsaD proteins could be cross-linked with PsaC, but the PsaD-PsaL cross-linked product was reduced drastically when arginine-72, Lys-74, and Lys-76 were mutated simultaneously. These studies demonstrate that the basic residues in the central region of PsaD, especially Lys-74, are crucial in the assembly of PsaD into the PSI complex.