Michael J. Lochhead

Background Point‐of‐care (POC) CD4 T‐cell counting is increasingly recognized as providing improved linkage‐to‐care during management of HIV infection, particularly in resource‐limited settings where disease burden is highest. This study evaluated prototype POC CD4 T‐cell counters from MBio Diagnostics in the context of low CD4 count, hospitalized patients in Mozambique. This study measured system performance when presented with challenging, low count samples from HIV/AIDS patients with acute illnesses resulting in hospitalization. Methods Forty whole blood samples were collected from donors on the medical service at Maputo Central Hospital and absolute CD4 counts were generated on the MBio CD4 system and a reference laboratory using flow cytometry. Results The mean and median CD4 counts by the flow cytometry reference were 173 and 80 cells/µL, respectively. Correlation between the MBio CD4 System and the reference was good. Bland‐Altman analysis showed a mean bias of +15 cells/µL (+9 to +21 cells/µL, 95% CI), and limits of agreement of −47 to 77 cells/µL. For samples with counts >100 cells/µL (N = 14), the mean coefficient of variation was 7.3%. For samples with counts <50 cells/µL, mean absolute bias of replicate samples was 4.8 cells/µL. When two MBio readers were compared, Bland‐Altman bias was −4 cells/µL (−13 to +6 cells/µL, 95% CI), and limits of agreement of −63 and +55 cells/µL. Conclusions The MBio System holds promise as a POC system for quantitation of CD4 T cells in resource‐limited settings given system throughput (80–100 cartridges/day), design simplicity, and ease‐of‐use. © 2015 International Clinical Cytometry Society

Diagnosis of opportunistic infections in HIV-infected individuals remains a major public health challenge, particularly in resource-limited settings. Here, we describe a rapid diagnostic system that delivers a panel of serologic immunoassay results using a single drop of blood, serum, or plasma. The system consists of disposable cartridges and a simple reader instrument, based on an innovative implementation of planar waveguide imaging technology. The cartridge incorporates a microarray of recombinant antigens and antibody controls in a fluidic channel, providing multiple parallel fluorescence immunoassay results for a single sample. This study demonstrates system performance by delivering antibody (Ab) reactivity results simultaneously for multiple antigens of HIV-1,Treponema pallidum(syphilis), and hepatitis C virus (HCV) in a collection of clinical serum, plasma, and whole-blood samples. By plotting antibody reactivity (fluorescence intensity) for known positive and negative samples, empirical reactivity cutoff values were defined. The HIV-1 assay shows 100% agreement with known seroreactivity for a collection of 82 HIV Ab-positive and 142 HIV Ab-negative samples, including multiple samples with HCV and syphilis coinfection. The treponema-specific syphilis assay correctly identifies 67 of 68T. pallidumAb-positive and 100 of 102T. pallidumAb-negative samples, and the HCV assay correctly identifies 59 of 60 HCV Ab-positive and 120 of 121 HCV Ab-negative samples. Multiplexed assay performance for whole-blood samples is also demonstrated. The ability to diagnose HIV and opportunistic infections simultaneously at the point of care should lead to more effective therapy decisions and improved linkage to care.

The 2010 HIV Diagnostics Conference brought together approximately 260 representatives from public health laboratories, test manufacturers and federal agencies for a series of test method and technology presentations, as well as policy discussions related to HIV screening in the USA. The meeting was particularly substantive in the context of moving toward a consensus laboratory testing algorithm that capitalizes on the improved sensitivities and turnaround times associated with newer technologies. This article provides a brief overview of several meeting topics, including point-of-care testing algorithms, fourth-generation immunoassays, recency testing and new technologies.