Evaluation of the Panbio COVID-19 Antigen Rapid Diagnostic Test in Subjects Infected with Omicron Using Different Specimens.

Community testing is a crucial tool for the early identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and transmission control. The emergence of the highly mutated Omicron variant (B.1.1.529) raised concerns about its primary site of replication, impacting sample collection and its detectability by rapid antigen tests. We tested the performance of the Panbio antigen rapid diagnostic test (Ag-RDT) using nasal and oral specimens for COVID-19 diagnosis in 192 symptomatic individuals, with quantitative reverse transcription-PCR (RT-qPCR) of nasopharyngeal samples as a control. Variant of concern (VOC) investigation was performed with the 4Plex SARS-CoV-2 screening kit. The SARS-CoV-2 positivity rate was 66.2%, with 99% of the positive samples showing an amplification profile consistent with that of the Omicron variant. Nasal Ag-RDT showed higher sensitivity (89%) than oral (12.6%) Ag-RDT. Our data showed good performance of the Ag-RDT in a pandemic scenario dominated by the Omicron VOC. Furthermore, our data also demonstrated that the Panbio COVID-19 antigen rapid diagnostic test does not provide good sensitivity with oral swabs for Omicron Ag-RDT detection. IMPORTANCE This study showed that the antigen rapid test for COVID19 worked fine using nasal swabs when it was utilized in patients infected with the Omicron variant, showing a concordance with PCR in 93% of patients tested. The nasal swab yielded more reliable results than the oral swab when an antigen rapid diagnosis test (the Panbio COVID-19 antigen rapid diagnostic test) was used in patients infected with the Omicron variant.

Association between KIR genotypes and HLA-B alleles on viral load in Southern Brazilian individuals infected by HIV-1 subtypes B and C.

There is a great variety of HIV-1 subtypes circulating in Brazil, including subtype C, whose prevalence is on the rise, particularly in the southern region. Many host and viral genetic factors may be involved in this trend. We evaluated the influence of human leukocyte antigen (HLA) class I alleles and killer-cell immunoglobulin-like receptor (KIR) genotypes on viral set point and T-CD4(+) parameters in 84 treatment-naïve HIV-1-positive individuals. Frequency data in the infected group were compared to data of 548 healthy control subjects. Individuals with the KIR AA genotype had a higher viral load (VL) than individuals with the KIR Bx genotype. The HIV-1 group was subdivided into three subgroups according to HLA-B allele presence: those with protection to disease alleles (HLA-B(+)), accelerated disease progression alleles (HLA-B(-)), or neither (HLA-B(o)) were grouped. We observed a significant effect of the HLA-B allele presence on VL. The HLA-B(+) group had significantly lower VL than the HLA-B(-) group and trended toward a lower VL than the HLA-B(o) group. There were significant differences between groups expressing extreme VL values: KIR-AA+HLA-B(-) vs. KIR Bx+HLA-B(+) and KIR-AA+HLA-B(o)vs. KIR Bx+HLA-B(+). The relationship of KIR/HLA host genetics with slow HIV disease progression in southern Brazil may be useful for vaccine developers, epidemiologists, and clinicians.