An Assessment of a Rapid SARS-CoV-2 Antigen Test in Bangladesh

Early detection of SARS-CoV-2 infection is crucial to prevent its spread. This study aimed to document test sensitivity/specificity, correlation with cycle threshold value from polymerase chain reaction (PCR), fitness-for-use in different populations and settings, and user perspectives that could inform large-scale implementation. In this study, we evaluated the performance of a rapid antigen detection test, BD Veritor, and compared this (and another rapid test, Standard Q) against reverse transcription PCR (RT-PCR) in terms of sensitivity and specificity in 130 symptomatic and 130 asymptomatic adults. In addition, we evaluated the suitability and ease of use of the BD Veritor test in a subsample of study participants (n = 42) and implementers (n = 5). At 95% confidence interval, the sensitivity of the BD Veritor and Standard Q test were 70% and 63% in symptomatic and 87% and 73% in asymptomatic individuals, respectively, regarding positive SARS-CoV-2 RT-PCR results. Overall, the BD Veritor test was 78% sensitive and 99.5% specific compared with RT-PCR irrespective of the cycle threshold. This warrants large field evaluation as well as use of the rapid antigen test for quick assessment of SARS-CoV-2 for containment of epidemics in the country.

Medical cannabis and cannabidiol: A new harvest for Malawi

In February 2020 parliament passed the Cannabis Regulation Bill (2020) which regulates the cultivation and production of industrial hemp and medical cannabis. The country will only fully benefit from this development if the medical and scientific community can take the lead in enabling the country to exploit the plant's potential to help address some of our economic and public health challenges. This special communication provides some basic information on cannabis and discusses its history and medical uses. Cannabidiol (CBD) has emerged as one of the most important cannabis-derived phytochemicals and has formed the basis for the growth of the medical cannabis industry. The scientific data on the mechanisms of the effects of CBD on the human neuroendocrine-immune network is reviewed and the first effective cannabis-based FDA-approved treatment for epilepsy discussed. Some clinical research that is being done on the antipsychotic and neuroprotective properties of CBD is also reviewed. A case is made for the potential of CBD as a neuroprotective adjunctive therapy for the prevention of neuropsychological sequelae associated with complicated malaria. The safety profile of CBD is reviewed and finally, the potential importance of the re-medicalization of cannabis-based therapies for the broader field of phytomedicine is pointed out.

Assessment of performance and implementation characteristics of rapid point of care SARS-CoV-2 antigen testing

Background: The COVID-19 pandemic has resulted in a need for rapid identification of infectious cases. Testing barriers have prohibited adequate screening for SARS-CoV-2, resulting in significant delays in commencement of treatment and outbreak control measures. This study aimed to generate evidence on the performance and implementation characteristics of the BD Veritor™ Plus System rapid antigen test as compared to reverse transcription polymerase chain reaction (RT-PCR) for diagnosis of SARS-CoV-2 in Kenya. Methods: This was a field test performance evaluation in adults undergoing testing for SARS-CoV-2. Recruited participants were classified as SARS-CoV-2-positive based on RT-PCR carried out on nasopharyngeal swabs. Antigen tests were performed with simultaneous RT-PCR on 272 participants, allowing estimation of sensitivity, specificity, positive and negative predictive values for the rapid antigen test. Implementation characteristics were assessed. Results: We enrolled 97 PCR negative symptomatic and 128 PCR negative asymptomatic, and 28 PCR positive symptomatic and 19 PCR positive asymptomatic participants. Compared to RT-PCR, the sensitivity of the rapid antigen test was 94% (95% confidence interval [CI] 86.6 to 100.0) while the specificity was 98% (95% CI 96 to 100). There was no association between sensitivity and symptom status, or between the cycle threshold value and sensitivity of the BD Veritor. The rapid test had a quick turnaround time, required minimal resources, and laboratory personnel conducting testing found it easier to use than RT-PCR. The relatively high sensitivity of BD Veritor may be partially attributed to shortages of RT-PCR testing materials, resulting in specimen analysis delays and potential degradation of viral genetic material. Therefore, in resource-constrained settings, rapid antigen tests may perform better than the reference RT-PCR, resulting in prompt institution of isolation and treatment measures.  Conclusion: The BD Veritor rapid antigen test’s high sensitivity should be interpreted with consideration to the challenges occasioned by RT-PCR testing in resource-constrained settings.

ADCC-mediating non-neutralizing antibodies can exert immune pressure in early HIV-1 infection

Despite antibody-dependent cellular cytotoxicity (ADCC) responses being implicated in protection from HIV-1 infection, there is limited evidence that they control virus replication. The high mutability of HIV-1 enables the virus to rapidly adapt, and thus evidence of viral escape is a very sensitive approach to demonstrate the importance of this response. To enable us to deconvolute ADCC escape from neutralizing antibody (nAb) escape, we identified individuals soon after infection with detectable ADCC responses, but no nAb responses. We evaluated the kinetics of ADCC and nAb responses, and viral escape, in five recently HIV-1-infected individuals. In one individual we detected viruses that escaped from ADCC responses but were sensitive to nAbs. In the remaining four participants, we did not find evidence of viral evolution exclusively associated with ADCC-mediating non-neutralizing Abs (nnAbs). However, in all individuals escape from nAbs was rapid, occurred at very low titers, and in three of five cases we found evidence of viral escape before detectable nAb responses. These data show that ADCC-mediating nnAbs can drive immune escape in early infection, but that nAbs were far more effective. This suggests that if ADCC responses have a protective role, their impact is limited after systemic virus dissemination.

A 14-day follow-up of adult non-malarial fever patients seen by mobile clinics in rural Malawi

Background

While health providers consistently use malaria rapid diagnostic tests to rule out malaria, they often lack tools to guide treatment for those febrile patients who test negative. Without the tools to provide an alternative diagnosis, providers may prescribe unnecessary antibiotics or miss a more serious condition, potentially contributing to antibiotic resistance and/or poor patient outcomes.

Methods

This study ascertained which diagnoses and treatments might be associated with poor outcomes in adults who test negative for malaria. Adult patients for rapid diagnostic test of malaria seen in mobile health clinics in Mulanje and Phalombe districts were followed for 14 days. Participants were interviewed on sociodemographic characteristics, health-seeking behaviour, diagnosis, treatment and access to care. Mobile clinic medical charts were reviewed. Two weeks (±2 days) following clinic visit, follow-up interviews were conducted to assess whether symptoms had resolved.

Results

Initially, 115 adult patients were enrolled and 1 (0.88%) was lost to follow-up. Of the 114 adult patients remaining in the study, 55 (48%) were seen during the dry season and 59 (52%) during the wet season. Symptoms resolved in 90 (80%) patients at the 14-day follow-up visit (n=90) with the rest (n=24) reporting no change in symptoms. None of the patients in the study died or were referred for further care. Almost all patients received some type of medication during their clinic visit (98.2%). Antibiotics were given to 38.6% of patients, and virtually all patients received pain or fever relief (96.5%). However, no anti-malarials were prescribed.

Conclusions

Mobile clinics provide important health care where access to care is limited. Although rapid tests have guided appropriate treatment, challenges remain when a patient's presenting complaint is less well defined. In rural areas of southern Malawi, simple diagnostics are needed to guide treatment decisions.

Distinct Biomarker Profiles Distinguish Malawian Children with Malarial and Non-malarial Sepsis

Presently, it is difficult to accurately diagnose sepsis, a common cause of childhood death in sub-Saharan Africa, in malaria-endemic areas, given the clinical and pathophysiological overlap between malarial and non-malarial sepsis. Host biomarkers can distinguish sepsis from uncomplicated fever, but are often abnormal in malaria in the absence of sepsis. To identify biomarkers that predict sepsis in a malaria-endemic setting, we retrospectively analyzed data and sera from a case-control study of febrile Malawian children (aged 6-60 months) with and without malaria who presented to a community health center in Blantyre (January-August 2016). We characterized biomarkers for 29 children with uncomplicated malaria without sepsis, 25 without malaria or sepsis, 17 with malaria and sepsis, and 16 without malaria but with sepsis. Sepsis was defined using systemic inflammatory response criteria; biomarkers (interleukin-6 [IL-6], tumor necrosis factor receptor-1, interleukin-1 β [IL-1β], interleukin-10 [IL-10], von Willebrand factor antigen-2, intercellular adhesion molecule-1, and angiopoietin-2 [Ang-2]) were measured with multiplex magnetic bead assays. IL-6, IL-1β, and IL-10 were elevated, and Ang-2 was decreased in children with malaria compared with non-malarial fever. Children with non-malarial sepsis had greatly increased IL-1β compared with the other subgroups. IL-1β best predicted sepsis, with an area under the receiver operating characteristic (AUROC) of 0.71 (95% CI: 0.57-0.85); a combined biomarker-clinical characteristics model improved prediction (AUROC of 0.77, 95% CI: 0.67-0.85). We identified a distinct biomarker profile for non-malarial sepsis and developed a sepsis prediction model. Additional clinical and biological data are necessary to further explore sepsis pathophysiology in malaria-endemic regions.

Antibody-Dependent Cellular Cytotoxicity (ADCC)-Mediating Antibodies Constrain Neutralizing Antibody Escape Pathway

Both neutralization and antibody-dependent cellular cytotoxicity (ADCC) may be required for effective protection against HIV-1 infection. While there is extensive information on the targets of early neutralizing antibody (nAb) responses, much less is known about the targets of ADCC responses, which are more difficult to characterize. In four individuals recruited during acute HIV-infection, ADCC responses were detected 3-7 weeks prior to nAb responses. To determine the relative influence of ADCC and nAb responses on virus evolution, we performed an in-depth investigation of one individual (CAP63) who showed the highest nAb and ADCC responses. Both nAbs and ADCC antibodies targeted the V4 region of the Env, although there were some differences in epitope recognition. We identified accelerated viral evolution in this region concurrent with emergence of nAb activity, but not ADCC activity. Deep sequencing demonstrated that most nAb escape mutations were strongly selected for, however one nAb escape mutation that rendered the virus highly susceptible to autologous ADCC responses, was suppressed despite not affecting viral fitness. This escape mutation also rendered the virus more sensitive to autologous responses, as well as monoclonal antibodies targeting CD4-induced epitopes, compared to the wildtype virus. In conclusion, ADCC responses and nAbs in donor CAP63 recognized overlapping but unique epitopes in the V4 region, and while ADCC activity was present prior to nAbs, it did not drive viral evolution during this time. However, ADCC responses may select against nAb escape pathways that expose other common ADCC epitopes thereby restricting viral replication and expansion.

'Not all fevers are malaria': a mixed methods study of non-malarial fever management in rural southern Malawi

INTRODUCTION

With the ability to diagnose malaria with rapid diagnostic tests (mRDT), interest in improving diagnostics for non-malarial fevers has increased. Understanding how health providers diagnose and treat fevers is important for identifying additional tools to improve outcomes and reduce unnecessary antibiotic prescribing, particularly in areas where access to laboratory diagnostics is limited. This study aimed to understand rural health providers' practice patterns, both quantitatively and qualitatively, and influences on diagnostic and treatment decision-making.

METHODS

A mixed-methods study was conducted in Mulanje and Phalombe districts in southern Malawi. Retrospective data on diagnoses and treatments of febrile illness from seven mobile clinic logbooks were collected for a 2-month period in both the dry and wet seasons. Mobile health clinics visited remote villages in southern Malawi once every 7 days. Records from all patients with a recorded axillary temperature of 37.5ºC or higher or reported history of fever within 48 hours, and a negative mRDT, were included in the analysis. Key informant interviews were conducted with 31 mobile clinic health workers who triage, diagnose, and treat patients as well as dispense medication.

RESULTS

In total, 30 672 febrile patients were seen during the study period. Of those, 9924 (32%) tested negative for malaria by mRDT. Acute respiratory infection was the most common diagnosis for mRDT-negative patients (44.6%), and this number increased in the rainy season as compared to the dry season (odds ratio=2.18, 95% confidence interval=2.01-2.36). Over half (60%) of mRDT-negative patients received antibiotics as a treatment. Almost all the health providers in this study reported limited training in non-malarial fever management, despite the fact that roughly 30% of all patients with fever seen at the mobile clinics tested negative by mRDT. Without diagnostic tools beyond mRDTs, providers relied heavily on patient history to guide treatment decisions.

CONCLUSION

Additional simple-to-use diagnostic tests as well as additional training in patient examination and clinical assessment are needed in rural settings where health providers risk over-prescribing antibiotics or missing a potentially dangerous infection in febrile patients who test negative for malaria.

Characterizing Pediatric Non-Malarial Fever and Identifying the At-Risk Child in Rural Malawi

Objective. To characterize children with non–malarial fever at risk of nonrecovery or worsening in rural Malawi. Methods. This is a subgroup analysis of patients ≤14 years of age from a prospective cohort study in non–malarial fever subjects (temperature ≥37.5°C, or fever within 48 hours, and malaria negative) in southern Malawi cared for at a mobile clinic during the 2016 dry (August to September) or wet (November to December) season. Data collection included chart review and questionnaires; 14-day follow-up was conducted. We conducted univariate descriptive statistics on cohort characteristics, bivariate analyses to examine associations between characteristics and outcomes, and multivariate logistic regressions to explore factors associated with nonrecovery. Results. A total of 2893 patients were screened, 401 were enrolled, 286 of these were children, and 280 children completed follow-up. Eighty-seven percent reported symptom resolution, 12.9% reported no improvement, and there were no deaths or hospitalizations. No improvement was associated with dry season presentation (42.6% vs 75.0%, P < .0003), >2 days of symptoms (51.6% vs 72.2%, P = .03), and food insecurity (62.3% vs 86.1%, P = .007). Dry season subjects had a 4.35 times greater likelihood of nonimprovement (95% confidence interval [CI] = 1.96-11.11). Household food insecurity and being >2 hours from a permanent clinic were associated with no improvement (adjusted odds ratio [AOR] = 4.61, 95% CI = 1.81-14.29; and AOR = 2.38, 95% CI = 1.11-5.36, respectively). Conclusion. Outcomes were generally excellent in this rural, outpatient pediatric cohort, though risk factors for nonrecovery included food insecurity, access to a standing clinic, and seasonality. Ideally, this study will inform clinic- and policy-level changes aimed at ameliorating the modifiable risk factors in Malawi and throughout rural Africa.

Short Communication: A Recombinant Variant with Increased Envelope Entry Efficiency Emerged During Early Infection of an HIV-1 Subtype C Dual Infected Rapid Progressor

Mutations in functionally constrained sites of the HIV envelope (Env) can affect entry efficiency and are potential targets for vaccine and drug design. We investigated Du151, a dual-infected individual with rapid disease progression. At her death 19 months postinfection (mpi), she was infected with a recombinant variant, which outgrew both parental viruses. We aimed to determine whether the recombinant virus had enhanced Env entry efficiency compared to the parental viruses and to identify the functional determinant. We generated 15 env clones at 1, 2, 8, and 19 mpi. Pseudovirus carrying a recombinant Env clone (PSV clone), C18 (19 mpi), had significantly higher entry efficiency compared to the parents, suggesting that the recombinant virus had enhanced fitness. To identify the functional determinant, we compared two recombinant PSV clones (C18 and C63)-differing in entry efficiency (2-fold) and by four and three amino acids in gp120 and gp41, respectively. The increased entry efficiency of a C18-gp41 PSV chimera indicated that the three amino acids in the C18 gp41 region were involved (K658, G671, and F717). Site-directed mutagenesis of the three amino acids of C63 showed that a single amino acid mutation, R658K, increased pseudovirion entry efficiency. The introduction of R658 into two PSV clones (C1 and C18) decreased their entry efficiency, suggesting that R658 carries a fitness cost. Thus, our data suggest that a recombinant virus emerged at 19 mpi with enhanced Env entry efficiency. Therefore, K658 in gp41 could in part be a contributing factor to the increased viral load and rapid disease progression of Du151.

CAPRISA 004 tenofovir microbicide trial: no impact of tenofovir gel on the HIV transmission bottleneck

Alterations of the genital mucosal barrier may influence the number of viruses transmitted from a human immunodeficiency virus-infected source host to the newly infected individual. We used heteroduplex tracking assay and single-genome sequencing to investigate the effect of a tenofovir-based microbicide gel on the transmission bottleneck in women who seroconverted during the CAPRISA 004 microbicide trial. Seventy-seven percent (17 of 22; 95% confidence interval [CI], 56%-90%) of women in the tenofovir gel arm were infected with a single virus compared with 92% (13 of 14; 95% CI, 67%->99%) in the placebo arm (P = .37). Tenofovir gel had no discernable impact on the transmission bottleneck.

Defining the human immunodeficiency virus type 1 transmission genetic bottleneck in a region with multiple circulating subtypes and recombinant forms

The Mbeya region of Tanzania has a genetically complex HIV epidemic with multiple subtypes and recombinant forms circulating, together with a high frequency of dual infections with more than one subtype. This study aimed to determine whether this impacted the HIV-1 transmission bottleneck. A total of 210 env sequences from 22 participants were generated from recently infected women from Mbeya using the single genome amplification approach. Participants were infected with subtypes C (n=9), A (n=4), or D (n=1), and recombinants AC (n=4), CD (n=2), AD (n=1), or ACD (n=1). Sixteen participants (73%) were infected with a single variant; five (23%) with multiple variants; and one (4%) was dually infected. Thus the frequency of single variant infections was similar to cohorts located in genetically restricted subtype B or C epidemics, suggesting that multiple circulating subtypes and unique recombinant forms do not have a significant impact on the transmission bottleneck.

Limited neutralizing antibody specificities drive neutralization escape in early HIV-1 subtype C infection

We previously showed that HIV-1 subtype C viruses elicit potent but highly type-specific neutralizing antibodies (nAb) within the first year of infection. In order to determine the specificity and evolution of these autologous nAbs, we examined neutralization escape in four individuals whose responses against the earliest envelope differed in magnitude and potency. Neutralization escape occurred in all participants, with later viruses showing decreased sensitivity to contemporaneous sera, although they retained sensitivity to new nAb responses. Early nAb responses were very restricted, occurring sequentially and targeting only two regions of the envelope. In V1V2, limited amino acid changes often involving indels or glycans, mediated partial or complete escape, with nAbs targeting the V1V2 region directly in 2 cases. The alpha-2 helix of C3 was also a nAb target, with neutralization escape associated with changes to positively charged residues. In one individual, relatively high titers of anti-C3 nAbs were required to drive genetic escape, taking up to 7 weeks for the resistant variant to predominate. Thereafter titers waned but were still measurable. Development of this single anti-C3 nAb specificity was associated with a 7-fold drop in HIV-1 viral load and a 4-fold rebound as the escape mutation emerged. Overall, our data suggest the development of a very limited number of neutralizing antibody specificities during the early stages of HIV-1 subtype C infection, with temporal fluctuations in specificities as escape occurs. While the mechanism of neutralization escape appears to vary between individuals, the involvement of limited regions suggests there might be common vulnerabilities in the HIV-1 subtype C transmitted envelope.