A field bioassay for assessing ivermectin bio-efficacy in wild malaria vectors.

BACKGROUND: Ivermectin (IVM) mass drug administration is a candidate complementary malaria vector control tool. Ingestion of blood from IVM treated hosts results in reduced survival in mosquitoes. Estimating bio-efficacy of IVM on wild-caught mosquitoes requires they ingest the drug in a blood meal either through a membrane or direct feeding on a treated host. The latter, has ethical implications, and the former results in low feeding rates. Therefore, there is a need to develop a safe and effective method for IVM bio-efficacy monitoring in wild mosquitoes. METHODS: Insectary-reared Anopheles gambiae s.s. were exposed to four IVM doses: 85, 64, 43, 21 ng/ml, and control group (0 ng/ml) in three different solutions: (i) blood, (ii) 10% glucose, (iii) four ratios (1:1, 1:2, 1:4, 1:8) of blood in 10% glucose, and fed through filter paper. Wild-caught An. gambiae s.l. were exposed to 85, 43 and 21 ng/ml IVM in blood and 1:4 ratio of blood-10% glucose mixture. Survival was monitored for 28 days and a pool of mosquitoes from each cohort sacrificed immediately after feeding and weighed to determine mean weight of each meal type. RESULTS: When administered in glucose solution, mosquitocidal effect of IVM was not comparable to the observed effects when similar concentrations were administered in blood. Equal concentrations of IVM administered in blood resulted in pronounced reductions in mosquito survival compared to glucose solution only. However, by adding small amounts of blood to glucose solution, mosquito mortality rates increased resulting in similar effects to what was observed during blood feeding. CONCLUSION: Bio-efficacy of ivermectin is strongly dependent on mode of drug delivery to the mosquito and likely influenced by digestive processes. The assay developed in this study is a good candidate for field-based bio-efficacy monitoring: wild mosquitoes readily feed on the solution, the assay can be standardized using pre-selected concentrations and by not involving treated blood hosts (human or animal) variation in individual pharmacokinetic profiles as well as ethical issues are bypassed. Meal volumes did not explain the difference in the lethality of IVM across the different meal types necessitating further research on the underlying mechanisms.

Women's preferences, expectations, and experiences with male partner support throughout prevention of mother to child transmission of HIV services: a mixed-methods study.

Male involvement in prevention of mother to child transmission of HIV (PMTCT) care improves maternal and child outcomes. We conducted a mixed-methods study at two Kenyan government hospitals. We quantitatively assessed women's expectations and preferences for male partner involvement in PMTCT and male partner attendance at PMTCT appointments. Qualitative interviews with women during the postpartum period assessed types of support women received from their male partners. At enrollment, most participants wanted (75%) and expected (69%) male partners to attend appointments; yet, only 9% had a male partner attend any appointments. Most women agreed that their partner would: support them financially (81%), help follow doctor's guidance (61%), support a hospital-based delivery (85%), and want to receive text messages (68%). Expectations and preferences varied by women's characteristics, most notably experiences with mistreatment, disclosure status, and knowledge of male partner's HIV status. In qualitative interviews, instrumental (financial) support was the most frequently discussed type of support. Male partners also provided informational support by reminding women of medication or appointments. Women reported a variety of ways in which their male partners supported them through PMTCT; however, there was a gap between women's expectation for male partner attendance and the level of male attendance achieved.

"Closing the Gap": Provider Recommendations for Implementing Birth Point of Care HIV Testing.

Delays in traditional HIV DNA PCR testing for early infant diagnosis (EID) at 6 weeks of age result in late antiretroviral treatment (ART). Birth point of care (POC) testing is an emerging strategy with the potential to streamline EID services. We elicited providers' recommendations for introducing birth POC testing to guide strategies in Kenya and similar settings. We conducted formative interviews with 26 EID providers from four Kenyan hospitals prior to POC implementation. Providers discussed the need for comprehensive training, covering both EID and POC-specific topics for all key personnel. Providers highlighted equipment considerations, such as protocols for maintenance and safe storage. Providers emphasized the need for maternal counseling to ensure patient acceptance and most agreed that specimen collection for birth POC testing should occur in the maternity department and supported a multidisciplinary approach. Though most providers supported ART initiation based on a positive birth POC result, a few expressed concerns with result validity. To maximize implementation success, provider training, equipment security, maternal counseling, and logistics of testing must be planned and communicated to providers.

Structures of the phage Sf6 large terminase provide new insights into DNA translocation and cleavage.

Many DNA viruses use powerful molecular motors to cleave concatemeric viral DNA into genome-length units and package them into preformed procapsid powered by ATP hydrolysis. Here we report the structures of the DNA-packaging motor gp2 of bacteriophage Sf6, which reveal a unique clade of RecA-like ATPase domain and an RNase H-like nuclease domain tethered by a regulatory linker domain, exhibiting a strikingly distinct domain arrangement. The gp2 structures complexed with nucleotides reveal, at the atomic detail, the catalytic center embraced by the ATPase domain and the linker domain. The gp2 nuclease activity is modulated by the ATPase domain and is stimulated by ATP. An extended DNA-binding surface is formed by the linker domain and the nuclease domain. These results suggest a unique mechanism for translation of chemical reaction into physical motion of DNA and provide insights into coordination of DNA translocation and cleavage in a viral DNA-packaging motor, which may be achieved via linker-domain-mediated interdomain communication driven by ATP hydrolysis.

The structure of the herpes simplex virus DNA-packaging terminase pUL15 nuclease domain suggests an evolutionary lineage among eukaryotic and prokaryotic viruses.

Herpes simplex virus 1 (HSV-1), the prototypic member of herpesviruses, employs a virally encoded molecular machine called terminase to package the viral double-stranded DNA (dsDNA) genome into a preformed protein shell. The terminase contains a large subunit that is thought to cleave concatemeric viral DNA during the packaging initiation and completion of each packaging cycle and supply energy to the packaging process via ATP hydrolysis. We have determined the X-ray structure of the C-terminal domain of the terminase large-subunit pUL15 (pUL15C) from HSV-1. The structure shows a fold resembling those of bacteriophage terminases, RNase H, integrases, DNA polymerases, and topoisomerases, with an active site clustered with acidic residues. Docking analysis reveals a DNA-binding surface surrounded by flexible loops, indicating considerable conformational changes upon DNA binding. In vitro assay shows that pUL15C possesses non-sequence-specific, Mg(2+)-dependent nuclease activity. These results suggest that pUL15 uses an RNase H-like, metal ion-mediated catalysis mechanism for cleavage of viral concatemeric DNA. The structure reveals extra structural elements in addition to the RNase H-like fold core and variations in local architecture of the nuclease active site, which are conserved in herpesvirus terminases and bear great similarity to the phage T4 gp17 but are distinct from podovirus and siphovirus orthologs and cellular RNase H, delineating a new evolutionary lineage among a large family of eukaryotic viruses and simple and complex prokaryotic viruses.

Implementation research: a protocol for two three-arm pragmatic randomised controlled trials on continuous glucose monitoring devices in people with type 1 diabetes in South Africa and Kenya.

BACKGROUND: Self-monitoring of glucose is an essential component of type 1 diabetes (T1D) management. In recent years, continuous glucose monitoring (CGM) has provided an alternative to daily fingerstick testing for the optimisation of insulin dosing and general glucose management in people with T1D. While studies have been conducted to evaluate the impact of CGM on clinical outcomes in the US, Europe and Australia, there are limited data available for low- and middle-income countries (LMICs) and further empirical evidence is needed to inform policy decision around their use in these countries. METHODS: This trial was designed as a pragmatic, parallel-group, open-label, multicentre, three-arm, randomised (1:1:1) controlled trial of continuous or periodic CGM device use versus standard of care in people with T1D in South Africa and Kenya. The primary objective of this trial will be to assess the impact of continuous or periodic CGM device use on glycaemic control as measured by change from baseline glycosylated haemoglobin (HbA1c). Additional assessments will include clinical outcomes (glucose variation, time in/below/above range), safety (adverse events, hospitalisations), quality of life (EQ-5D, T1D distress score, Glucose Monitoring Satisfaction Survey for T1D), and health economic measures (incremental cost-effectiveness ratios, quality adjusted life years). DISCUSSION: This trial aims to address the substantial evidence gap on the impact of CGM device use on clinical outcomes in LMICs, specifically South Africa and Kenya. The trial results will provide evidence to inform policy and treatment decisions in these countries. TRIAL REGISTRATION: NCT05944731 (Kenya), July 6, 2023; NCT05944718 (South Africa), July 13, 2023.

Implementing at-birth, point-of-care HIV testing in Kenya: a qualitative study using the Consolidated Framework for Implementation Research.

BACKGROUND: At-birth and point-of-care (POC) testing can expedite early infant diagnosis of HIV and improve infant outcomes. Guided by the Consolidated Framework for Implementation Research (CFIR), this study describes the implementation of an at-birth POC testing pilot from the perspective of implementing providers and identifies the factors that might support and hinder the scale up of these promising interventions. METHODS: We conducted 28 focus group discussions (FGDs) with 48 providers across 4 study sites throughout the course of a pilot study assessing the feasibility and impact of at-birth POC testing. FGDs were audio-recorded, transcribed, and analyzed for a priori themes related to CFIR constructs. This qualitative study was nested within a larger study to pilot and evaluate at-birth and POC HIV testing. RESULTS: Out of the 39 CFIR constructs, 30 were addressed in the FGDs. While all five domains were represented, major themes revolved around constructs related to intervention characteristics, inner setting, and outer setting. Regarding intervention characteristics, the advantages of at-birth POC (rapid turnaround time resulting in improved patient management and enhanced patient motivation) were significant enough to encourage provider uptake and enthusiasm. Challenges at the intervention level (machine breakdown, processing errors), inner settings (workload, limited leadership engagement, challenges with access to information), and outer setting (patient-level challenges, limited engagement with outer setting stakeholders) hindered implementation, frustrated providers, and resulted in missed opportunities for testing. Providers discussed how throughout the course of the study adaptations to implementation (improved channels of communication, modified implementation logistics) were made to overcome some of these challenges. To improve implementation, providers cited the need for enhanced training and for greater involvement among stakeholders outside of the implementing team (i.e., other clinicians, hospital administrators and implementing partners, county and national health officials). Despite provider enthusiasm for the intervention, providers felt that the lack of engagement from leadership within the hospital and in the outer setting would preclude sustained implementation outside of a research setting. CONCLUSION: Despite demonstrated feasibility and enthusiasm among implementing providers, the lack of outer setting support makes sustained implementation of at-birth POC testing unlikely at this time. The findings highlight the multi-dimensional aspect of implementation and the need to consider facilitators and barriers within each of the five CFIR domains. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03435887 . Retrospectively registered on 19 February 2020.

Piloting the Feasibility and Preliminary Impact of Adding Birth HIV Polymerase Chain Reaction Testing to the Early Infant Diagnosis Guidelines in Kenya.

BACKGROUND: In Kenya, standard early infant diagnosis (EID) with polymerase chain reaction (PCR) testing at 6-week postnatal achieves early treatment initiation (<12 weeks) in <20% of HIV+ infants. Kenya's new early infant diagnosis guidelines tentatively proposed adding PCR testing at birth, pending results from pilot studies. METHODS: We piloted birth testing at 4 Kenyan hospitals between November 2017 and November 2018. Eligible HIV-exposed infants were offered both point-of-care and PCR HIV testing at birth (window 0 to <4 weeks) and 6 weeks (window 4-12 weeks). We report the: proportion of infants tested at birth, 6-week, and both birth and 6-week testing; median infant age at results; seropositivity and antiretroviral therapy initiation. RESULTS: Final sample included 624 mother-infant pairs. Mean maternal age was 30.4 years, 73.2% enrolled during antenatal care and 89.9% had hospital deliveries. Among the 590 mother-infants pairs enrolled before 4 weeks postnatal, 452 (76.6%) completed birth testing before 4 weeks, with 360 (79.6%) testing within 2 weeks, and 178 (39.4%) before hospital discharge (0-2 days). Mothers were notified of birth PCR results at a median infant age of 5.4 weeks. Among all 624 enrolled infants, 575 (92.1%) were tested during the 6-week window; 417 (66.8%) received testing at both birth and 6-weeks; and 207 received incomplete testing (93.3% only 1 PCR and 6.7% no PCR). Four infants were diagnosed with HIV, and 3 infants were initiated on antiretroviral therapy early, before 12 weeks of age. CONCLUSIONS: Uptake of PCR testing at birth was high and a majority of infants received repeat testing at 6 weeks of age.

Structural and functional studies of the phage Sf6 terminase small subunit reveal a DNA-spooling device facilitated by structural plasticity.

In many DNA viruses, genome packaging is initiated by the small subunit of the packaging terminase, which specifically binds to the packaging signal on viral DNA and directs assembly of the terminase holoenzyme. We have experimentally mapped the DNA-interacting region on Shigella virus Sf6 terminase small subunit gp1, which occupies extended surface areas encircling the gp1 octamer, indicating that DNA wraps around gp1 through extensive contacts. High-resolution structures reveal large-scale motions of the gp1 DNA-binding domain mediated by the curved helix formed by residues 54-81 and an intermolecular salt bridge formed by residues Arg67 and Glu73, indicating remarkable structural plasticity underlying multivalent, pleomorphic gp1:DNA interactions. These results provide spatial restraints for protein:DNA interactions, which enable construction of a three-dimensional pseudo-atomic model for a DNA-packaging initiation complex assembled from the terminase small subunit and the packaging region on viral DNA. Our results suggest that gp1 functions as a DNA-spooling device, which may transform DNA into a specific architecture appropriate for interaction with and cleavage by the terminase large subunit prior to DNA translocation into viral procapsid. This may represent a common mechanism for the initiation step of DNA packaging in tailed double-stranded DNA bacterial viruses.