Evaluation of the accuracy of the Asanté assay as a point-of-care rapid test for HIV-1 recent infections using serum bank specimens from blood donors in South Africa, July 2018 - August 2021.

BACKGROUND: Point-of-care (POC) rapid recency testing can be used as a cost-effective tool to identify recently infected individuals (i.e. infected within the last 12 months) in near-real time, support epidemic control and identify hotspots for transmission as part of recent infection surveillance. OBJECTIVE: To evaluate the performance of the Asanté (HIV-1) rapid recency assay as a POC rapid test among blood donors in South Africa (SA). METHODS: The study was a cross-sectional and validity study of the Asanté HIV-1 Rapid Recency Assay performed on 715 consecutively archived plasma donor specimens from the SA National Blood Services to determine their recency and established HIV infection status. ELISA and rapid assays for HIV antibody detection were used as the reference-testing standard for confirming an infection, while the Maxim HIV-1 limiting antigen (LAg) avidity assay was used as a reference for comparing HIV recency status. Validity tests (sensitivity, specificity, negative and positive predictive values) and Cohen-Kappa tests of the agreement were conducted to compare the Asanté HIV-1 rapid recency assay results with the reference tests. RESULTS: Of the 715 studied blood samples, 63.1% (n=451/715) were confirmed to be HIV-positive based on the reference standard. The sensitivity and specificity of the Asanté HIV-1 rapid recency assay in diagnosing established HIV infection compared to the ELISA were 98.4% (95% CI 96.7 - 99.3) and 99.6% (95% CI 97.6 - 100), respectively. Compared with HIV rapid assay, the sensitivity and specificity of the Asanté HIV-1 rapid recency assay was 98.7% (95% CI 97.0 - 99.4) and 99.2% (95% CI 97.1 - 100), respectively. Of the 451 HIV-positive blood samples, 43% were confirmed as recent HIV infections by the Maxim HIV-1 LAg avidity assay. There was high agreement between the Asanté HIV-1 rapid recency assay and the Maxim HIV-1 LAg avidity assay (94.1%, k=0.879, p<0.0001). The sensitivity and specificity of the Asante HIV-1 assay was 89.4% (95% CI 84.0 - 93.0) and 97.7% (95% CI 94.8 - 99.0), respectively. CONCLUSION: The Asanté HIV-1 rapid recency assay test results demonstrated high accuracy (>90%) compared with the HIV ELISA and rapid assays for determining established infection and the Maxim HIV-1 LAg avidity assay for classifying recent HIV-1 infections. The assay's sensitivity for established infections was below the World Health Organization criteria (<99%) for POC devices. The Asanté HIV-1 rapid recency assay can be used to distinguish between recent and long-term infections, but may not be considered a POC test for determining HIV infection.

Recency of HIV infection, antiretroviral therapy use and viral loads among symptomatic sexually transmitted infection service attendees in South Africa.

BACKGROUND: Better integration of HIV and sexually transmitted infection (STI) prevention and treatment services is needed to accelerate progress towards the goal of zero new HIV infections. OBJECTIVES: To describe HIV positivity, antiretroviral therapy (ART) use, viral suppression and recency of HIV infection among symptomatic STI service attendees at two primary care clinics in South Africa. METHODS: In a cross-sectional study, male and female STI service attendees presenting with symptoms consistent with STI syndromes were enrolled following informed consent. An interviewer-administered questionnaire was completed and appropriate genital and blood specimens were collected for STI testing and HIV biomarker measurements including recency of infection and antiretroviral (ARV) drug levels. Descriptive statistics were used to describe enrolled attendees, and to determine the proportion of attendees who were HIV-positive, recently infected, taking ART and virally suppressed. HIV-positive attendees with detectable ARVs were considered to be on ART, while those with viral loads (VLs) ≤200 copies/mL were considered virally suppressed. RESULTS: Of 451 symptomatic attendees whose data were analysed, 93 (20.6%) were HIV-positive, with 15/93 (16.1%) being recently infected. Recent infection was independently associated with genital ulcer disease at presentation, especially ulcers with no detectable STI pathogens. Among the 78 (83.9%) with long-term infection, only 30 (38.5%) were on ART, with 23/30 (76.7%) virally suppressed. CONCLUSIONS: In a population at risk of HIV transmission, there was a high burden of recent infection and unsuppressed VLs. Incorporating pre-exposure prophylaxis, ART initiation and adherence support into STI services will be necessary for progress towards eliminating HIV transmission.

Recency of HIV infection, antiretroviral therapy use and viral loads among symptomatic sexually transmitted infection service attendees in South Africa

Background. Better integration of HIV and sexually transmitted infection (STI) prevention and treatment services is needed to accelerate progress towards the goal of zero new HIV infections. Objectives. To describe HIV positivity, antiretroviral therapy (ART) use, viral suppression and recency of HIV infection among symptomatic STI service attendees at two primary care clinics in South Africa. Methods. In a cross-sectional study, male and female STI service attendees presenting with symptoms consistent with STI syndromes were enrolled following informed consent. An interviewer-administered questionnaire was completed and appropriate genital and blood specimens were collected for STI testing and HIV biomarker measurements including recency of infection and antiretroviral (ARV) drug levels. Descriptive statistics were used to describe enrolled attendees, and to determine the proportion of attendees who were HIV-positive, recently infected, taking ART and virally suppressed. HIV-positive attendees with detectable ARVs were considered to be on ART, while those with viral loads (VLs) ≤200 copies/mL were considered virally suppressed. Results. Of 451 symptomatic attendees whose data were analysed, 93 (20.6%) were HIV-positive, with 15/93 (16.1%) being recently infected. Recent infection was independently associated with genital ulcer disease at presentation, especially ulcers with no detectable STI pathogens. Among the 78 (83.9%) with long-term infection, only 30 (38.5%) were on ART, with 23/30 (76.7%) virally suppressed. Conclusions. In a population at risk of HIV transmission, there was a high burden of recent infection and unsuppressed VLs. Incorporating pre-exposure prophylaxis, ART initiation and adherence support into STI services will be necessary for progress towards eliminating HIV transmission

Monitoring diagnosis, retention in care and viral load suppression in children testing HIV polymerase chain reaction-positive in two districts in South Africa.

BACKGROUND: Retention in care is associated with improved virological control and survival among HIV-infected children. However, retention of children in HIV care remains a challenge. OBJECTIVES: To describe, using routine laboratory HIV test data, the retention-in-care and virological outcomes of HIV-infected children aged <18 months in two districts in South Africa. METHODS: HIV polymerase chain reaction (PCR)-positive results of children from uMkhanyakude and Tshwane districts in KwaZulu-Natal and Gauteng provinces, respectively, tested between April 2015 and May 2016, were extracted from the National Health Laboratory Service's Corporate Data Warehouse (CDW). HIV-related tests (PCR, viral load (VL), CD4+) were documented longitudinally for each child for ≥13 months after the first positive PCR result by manually searching demographics within the CDW, supplemented by an automated patient-linking algorithm. Test sets were linked if two or more demographics (surname, name, date of birth, folder number) matched exactly. Programmatic indicators assessed included age at first positive PCR test, presumed confirmatory test rates, retention in care, and VL suppression at 6 and 12 months. RESULTS: Ninety-four and 304 children tested HIV PCR-positive in uMkhanyakude and Tshwane, respectively. The median age at diagnosis was 3.6 months (interquartile range (IQR) 1.4 - 7.1) for uMkhanyakude and 2.3 months (IQR 0.1 - 6.7) for Tshwane. In uMkhanyakude, confirmed in utero infections accounted for 18.1% of transmissions (n=17), compared with 29.6% (n=90) in Tshwane. Presumed confirmatory test rates following an initial positive PCR result were 77.7% and 71.7% for uMkhanyakude and Tshwane, respectively. Within 6 months of starting antiretroviral therapy, 43 children (58.9%) were lost to follow-up in uMkhanyakude compared with 160 (73.4%) in Tshwane. Of those retained in care at 6 months with a VL measurement, 15 (60.0%) from uMkhanyakude had a VL <1 000 copies/mL, compared with 24 (48.0%) in Tshwane. For both districts, a third of all HIV PCR-positive children were retained in care at the end of follow-up, with 29 (30.9%) in uMkhanyakude and 99 (32.5%) in Tshwane. Of these, 12 (41.4%) had a VL <1 000 copies/mL in uMkhanyakude compared with 28 (28.3%) in Tshwane. CONCLUSIONS: We demonstrate the value of routine laboratory data in monitoring diagnosis, retention and VL suppression in HIV-infected children. This approach is scalable, can be reported near real-time, is relatively inexpensive to implement, and provides a tool for improving paediatric HIV services until clinical databases can assume this role.

Monitoring diagnosis, retention in care and viral load suppression in children testing HIV polymerase chain reaction-positive in two districts in South Africa

Background. Retention in care is associated with improved virological control and survival among HIV-infected children. However, retention of children in HIV care remains a challenge.Objectives. To describe, using routine laboratory HIV test data, the retention-in-care and virological outcomes of HIV-infected children aged <18 months in two districts in South Africa.Methods. HIV polymerase chain reaction (PCR)-positive results of children from uMkhanyakude and Tshwane districts in KwaZulu-Natal and Gauteng provinces, respectively, tested between April 2015 and May 2016, were extracted from the National Health Laboratory Service's Corporate Data Warehouse (CDW). HIV-related tests (PCR, viral load (VL), CD4+) were documented longitudinally for each child for ≥13 months after the first positive PCR result by manually searching demographics within the CDW, supplemented by an automated patient-linking algorithm. Test sets were linked if two or more demographics (surname, name, date of birth, folder number) matched exactly. Programmatic indicators assessed included age at first positive PCR test, presumed confirmatory test rates, retention in care, and VL suppression at 6 and 12 months.Results. Ninety-four and 304 children tested HIV PCR-positive in uMkhanyakude and Tshwane, respectively. The median age at diagnosis was 3.6 months (interquartile range (IQR) 1.4 - 7.1) for uMkhanyakude and 2.3 months (IQR 0.1 - 6.7) for Tshwane. In uMkhanyakude, confirmed in utero infections accounted for 18.1% of transmissions (n=17), compared with 29.6% (n=90) in Tshwane. Presumed confirmatory test rates following an initial positive PCR result were 77.7% and 71.7% for uMkhanyakude and Tshwane, respectively. Within 6 months of starting antiretroviral therapy, 43 children (58.9%) were lost to follow-up in uMkhanyakude compared with 160 (73.4%) in Tshwane. Of those retained in care at 6 months with a VL measurement, 15 (60.0%) from uMkhanyakude had a VL <1 000 copies/mL, compared with 24 (48.0%) in Tshwane. For both districts, a third of all HIV PCR-positive children were retained in care at the end of follow-up, with 29 (30.9%) in uMkhanyakude and 99 (32.5%) in Tshwane. Of these, 12 (41.4%) had a VL <1 000 copies/mL in uMkhanyakude compared with 28 (28.3%) in Tshwane.Conclusions. We demonstrate the value of routine laboratory data in monitoring diagnosis, retention and VL suppression in HIV-infected children. This approach is scalable, can be reported near real-time, is relatively inexpensive to implement, and provides a tool for improving paediatric HIV services until clinical databases can assume this role

Broad Feshbach resonance in the 6Li-40K mixture.

We study the widths of interspecies Feshbach resonances in a mixture of the fermionic quantum gases 6Li and 40K. We develop a model to calculate the width and position of all available Feshbach resonances for a system. Using the model, we select the optimal resonance to study the {6}Li/{40}K mixture. Experimentally, we obtain the asymmetric Fano line shape of the interspecies elastic cross section by measuring the distillation rate of 6Li atoms from a potassium-rich 6Li/{40}K mixture as a function of magnetic field. This provides us with the first experimental determination of the width of a resonance in this mixture, DeltaB=1.5(5) G. Our results offer good perspectives for the observation of universal crossover physics using this mass-imbalanced fermionic mixture.

Review Article - Experimental and Modeling Studies of Mass Transfer in Microencapsulated Cell Systems

Gaining a better understanding of mass transfer problems in encapsulated cell systems and in tissue engineering requires both experimental investigations and mathematical modelling. Specificmass transfer studies are reviewed including oxygen transfer in immobilised animal cell culture systems; modelling of electrostatic polymer droplet formation; and growth of plant somatic tissue encapsulated in alginate using electrostatics

Electrostatic encapsulation and growth of plant cell cultures in alginate.

The growth of callus tissue from African Violets, encapsulated in alginate using electrostatics, was investigated as well as the mechanism of alginate droplet formation. Alginate microbeads as small as 500 (+/-50) microns in diameter could be produced by electrostatic extrusion directly from a plastic syringe (1900 micron extrusion orifice), in the absence of a needle. Video analysis of the mechanism of electrostatic alginate droplet formation from the syringe showed the development of a Taylor cone-like droplet which extended to form a thin strand that then broke up into droplets. Autoclaving of the alginate/medium solution significantly reduced its viscosity, giving smaller beads. Calculated microbead diameters agreed well with experimental values. Callus tissue from leaf explants was successfully immobilized and cultured using electrostatic extrusion. Tissue immobilized using 4% alginate in medium and cultured on agar grew best, producing a complete plantlet within four months. The long-term aim is to develop an effective method for large production of artificial seeds.

Physico-chemical and mass transfer considerations in microencapsulation.

To gain better insight into mass transfer problems in encapsulated cell systems requires a combination of experimental investigations and mathematical modeling. Specific mass transfer studies are reviewed including oxygen transfer in immobilized animal cell culture bioreactors, modeling of polymer droplet formation and encapsulated animal cell growth, and growth of somatic tissue encapsulated in alginate using electrostatics. Special emphasis is given to electrostatic droplet generation for cell immobilization.

Investigations of Foodborne Diseases by Food Inspection Services in The Netherlands, 1991 to 1994.

Foodborne illnesses investigated in the period 1991 to 1994 by the regional Food Inspection Services in The Netherlands are summarized and evaluated. In this period 2,621 incidents were reported, involving 7,567 ill people. Types of food most commonly implicated were Chinese-Indonesian food and meat products. More than half of the incidents were reported to originate in a restaurant or snack bar. Although laboratory investigations were carried out when possible, a likely causative agent was identified in only 8.3% of the incidents. Of the incidents with a known etiological agent, 19% were attributed to Bacillus cereus , 16% to Salmonella spp., 11% to Clostridium perfringens , 10% to chemical toxins, 6% to Escherichia coli , and 5% to Staphylococcus aureus . The present system covers only a tiny proportion of all foodborne illness and does not utilize epidemiological evidence to identify the source of outbreaks. It is recommended to supplement the microbiological data collected at present with epidemiological evidence, in particular in outbreaks involving 10 people or more.

Modulation of protein release from chitosan-alginate microcapsules using the pH-sensitive polymer hydroxypropyl methylcellulose acetate succinate.

The release characteristics of protein from chitosan-alginate microcapsules prepared using an electrostatic droplet generator were evaluated. The release studies were undertaken in-vitro in simulated gastrointestinal fluids covering the pH range 1.2-8. Chitosan-alginate microcapsules showed unsatisfactory release properties, losing 94% of the encapsulated proteins (bovine serum albumin) over a 24 h period at pH 1.2. Incorporation of a pH-sensitive polymer, hydroxypropyl methylcellulose acetate succinate (HPMCAS), in the microcapsules, by coating the capsule membrane as well as blending with the capsule core polymer in varying ratios, produced significant changes in the release profiles of the microcapsules. At pH 1.2, the modified microcapsules retained up to 60% of the encapsulated protein after 24 h. The results obtained highlight the potential of HPMCAS as a release-modifier in chitosan-alginate microcapsules.

Role of polymers in improving the results of stenting in coronary arteries.

This article is a review of recent developments of polymer-related stents mainly employed in the coronary arteries, including polymer-coated stents, biostable stents and biodegradable stents. Polymer paving is covered as well. The problems with the stents currently investigated and the development of new stents are discussed.

Protective effects of polymer additives on animal cells exposed to rapidly falling liquid films.

The protective effects of polymer additives on insect cells against fluid mechanical damage was investigated in a falling film-flow device. The falling liquid film creates rapidly moving air-liquid interfaces and high fluid shear stress, mimicking the characteristics of a bursting bubble in aerated cell culture. The additives tested included a group of surface-active polymers, (i.e., Pluronic F68, poly(ethylene glycol)s, and Tween 80) and a group of viscosity-enhancing polymers (i.e., dextrans, methyl-cellulose, and (carboxymethyl)cellulose). We found that methylcellulose, which was previously considered a viscosity-enhancing polymer, actually had significant surface-active properties. All of the surface-active polymers exhibited significant protective effects, with Pluronic F68 and the higher molecular weight poly(ethylene glycol), PEG 20M, providing the best protection. In contrast, the viscosity-enhancing polymers, with the exception of methylcellulose, showed little or no protection for insect cells in the film flow. All of the protective polymers had surface-active properties, even though some of them did not change the surface tension in the actual insect cell medium. There was no correlation between the protective effect and the changes in liquid viscosity and surface tension due to the polymer additives. The level of protection was shown to be dependent upon the type of polymer, its concentration in the culture medium, and the polymer molecular weight. We concluded that the mechanism of protection of these surface-active polymers was through interaction of the polymer molecules with the cell plasma membranes: a fast-acting biological mechanism.

Mathematical modelling of immobilized animal cell growth.

A two-dimensional mathematical model for animal cell growth was employed to study the suspension, as well as stationary, culture of micro-encapsulated and gel immobilized animal cells. For stationary microcapsules with low-viscosity intracapsular liquid, it was found that capsule radius, capsule loading and medium-change time have the most significant effects on the intracapsular cell density. The model was also adapted to simulate other scenarios of cell growth such as in gel beads and suspended microcapsules. The simulated time course of oxygen concentration and specific growth rate revealed a complicated interaction between material transport and cell growth kinetics. With the mass transfer coefficient for oxygen transfer (KLa') into the medium equal to 4.0 hr-1, for instance, it was found that the specific growth rate of the microencapsulated cells was controlled by the supply of glucose and oxygen. When the value of KLa' was reduced to 0.6 hr-1, however, oxygen supply appeared to be the sole factor affecting the specific growth rate. In the case of suspended gel beads, a simulation revealed a higher cell density towards the gel bead surface. The transport of nutrients and oxygen to the central region of the gel bead was apparently blocked by the surrounding cells.

Biodegradable controlled antibiotic release devices for osteomyelitis: optimization of release properties.

Controlled antibiotic release films, melt-extruded cylinders, and suspension-extruded/coated cylinders were manufactured from biodegradable poly(D,L-lactide) (PDLLA) and poly(D,L-lactide-co-epsilon-caprolactone). These devices have potential application in the treatment of osteomyelitis. The in-vitro release properties of the devices were examined with drug loadings varying from 16 to 50%. Gentamicin sulphate films and melt-extruded gentamicin/PDLLA cylinders demonstrated a large initial burst and incomplete release. The films and melt-extruded cylinders made from poly(D,L-lactide-co-epsilon-caprolactone), low mol. wt poly(D,L-lactide), and a mixture of D,L-lactic acid oligomer and high mol. wt poly(D,L-lactide), did not remain intact during the entire release period. While this is undesirable, these materials do have the advantage of not requiring a processing temperature of greater than 110 degrees C. Antibiotic release from high mol. wt PDLLA-coated gentamicin/PDLLA cylinders, with 40 and 50% loading, was very rapid. The antibiotic could only diffuse out through the open ends of the cylinder. Coated gentamicin sulphate cylinders with 20 and 30% drug loading gave the most promising properties in terms of a small initial burst, and a gradual and sustained release. The release rate and duration from the coated cylinders could be adjusted by cutting the cylinder into different lengths; the time required for 90% of the entrapped gentamicin to be released into water from 30% loaded PDLLA-coated cylinders 0.2, 0.4, 0.7 and 1 cm in length was 1000, 1700, 2300, and 2800 h, respectively. This offers a convenient method to adjust the release to meet the specific antibiotic requirement of different patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Controlled release of albumin from chitosan-alginate microcapsules.

A polymeric delayed-release protein delivery system was investigated with albumin as a model drug. The polysaccharide chitosan was reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane. Variables believed to be important for membrane formation were examined; these included reaction time, chitosan molecular weight, alginate concentration, chitosan concentration, and solution pH. An alginate-chitosan reaction time, in the range of 10 to 45 min, had no effect on the release of albumin. Increasing the alginate concentration, however, resulted in a decreased rate of release of albumin (from 37% release at 4 h with 1.5% alginate to 20% release with 2.5% alginate). Another key variable was the chitosan molecular weight. The molecular weight of chitosan was varied from 1.25 x 10(6) to 0.25 x 10(6) through a nitrite oxidation reaction with sodium nitrite. Decreasing the molecular weight increased the release of albumin (from 37% release at 4 h with high molecular weight chitosan to 77% release with low molecular weight chitosan). The pH of the extracapsular environment was found to affect the release of albumin significantly (15% release over 24 h at a pH 3.0 and 73% release at pH 8.0). Capsules produced with high molecular weight chitosan and a combination of high and low molecular weight chitosan gave the best results for reducing elution of albumin in the first 4 h and increasing elution in the following 20 h.

Polysaccharide microcapsules and macroporous beads for enhanced chromatographic separation.

One recent solution to the diffusion problem found in conventional chromatographic separation is the use of dual porosity beads in which large pores allow for convective flow and smaller pores allow for molecular diffusion. In our studies, dual porosity beads were prepared from carrageenan using an emulsion method. Effects of polymer type, polymer concentration, toluene content, gelling temperature, and stirring speed on the structure of porous beads were investigated. In an alternative approach, one of the interacting molecules in affinity chromatography, can be entrapped within semipermeable microcapsules. This has the advantage of increased adsorption capacities. Using blue dextran and albumin as a model system, alginate-chitosan capsules, containing blue dextran, were employed in the recovery of albumin from a saline solution.