Validation Study for VERIPRO® SARS-CoV-2 Env Assay for the Detection of SARS-CoV-2 from Stainless-Steel Environmental Surface Swabs: Emergency Response Validation-AOAC Performance Tested MethodSM 122001.

Background: The VERIPRO® SARS-CoV-2 Env assay uses reverse transcriptase (RT) PCR to detect SARS-CoV-2, the causative agent of COVID-19, from stainless-steel environmental sample swabs.

Objective: To validate the VERIPRO SARS-CoV-2 Env assay as part of the AOAC Research Institute's Emergency Response Validation Performance Tested Method(s)SM program.

Method: The VERIPRO SARS-CoV-2 Env assay was evaluated for specificity using in silico analysis of 15 764 SARS-CoV-2 sequences and 65 exclusivity organisms (both near neighbors and background organisms).

Kinetically distinct processing pathways diversify the CD8 T cell response to a single viral epitope.

The source proteins from which CD8 T cell-activating peptides are derived remain enigmatic. Glycoproteins are particularly challenging in this regard owing to several potential trafficking routes within the cell. By engineering a glycoprotein-derived epitope to contain an N-linked glycosylation site, we determined that optimal CD8 T cell expansion and function were induced by the peptides that are rapidly produced from the exceedingly minor fraction of protein mislocalized to the cytosol.

Comparative Evaluation of Veriflow Species to USDA Culture-Based Method for the Detection of spp. in Food and Environmental Samples.

Veriflow® Listeria species (Veriflow LS) is a molecular-based assay for the presumptive detection of Listeria spp. from environmental surfaces (stainless steel, sealed concrete, plastic, and ceramic tile) and ready-to-eat (RTE) food matrixes (hot dogs and deli meat). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post-PCR amplification and requires only a 24 h enrichment for maximum sensitivity.

Comparative Evaluation of Veriflow Salmonella Species to USDA and FDA Culture-Based Methods for the Detection of spp. in Food and Environmental Samples.

Veriflow® Salmonella species (Veriflow SS) is a molecular-based assay for the presumptive detection of Salmonella spp. from environmental surfaces (stainless steel, sealed concrete, plastic, and ceramic tile), dairy (2% milk), raw meat (20% fat ground beef), chicken carcasses, and ready-to-eat (RTE) food (hot dogs). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post-PCR amplification and requires only an 18 h enrichment for maximum sensitivity.

Comparative Evaluation of Veriflow® Listeria monocytogenes to USDA and AOAC Culture Based Methods for the Detection of Listeria monocytogenes in Food.

Veriflow® Listeria monocytogenes (LM) is a molecular based assay for the presumptive detection of Listeria monocytogenes from environmental surfaces, dairy, and ready-to-eat (RTE) food matrixes (hot dogs and deli meat). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post PCR amplification and requires only 24 h of enrichment for maximum sensitivity. The Veriflow LM system eliminates the need for sample purification, gel electrophoresis, or fluorophore-based detection of target amplification, and does not require complex data analysis.

Impact of distinct poxvirus infections on the specificities and functionalities of CD4+ T cell responses.

Unlabelled: The factors that determine CD4+ T cell (TCD4+) specificities, functional capacity, and memory persistence in response to complex pathogens remain unclear. We explored these parameters in the C57BL/6 mouse through comparison of two highly related (>92% homology) poxviruses: ectromelia virus (ECTV), a natural mouse pathogen, and vaccinia virus (VACV), a heterologous virus that nevertheless elicits potent immune responses. In addition to elucidating several previously unidentified major histocompatibility complex class II (MHC-II)-restricted epitopes, we observed many qualitative and quantitative differences between the TCD4+ repertoires, including responses not elicited by VACV despite complete sequence conservation.

Epithelial immunization induces polyfunctional CD8+ T cells and optimal mousepox protection.

We assessed several routes of immunization with vaccinia virus (VACV) in protecting mice against ectromelia virus (ECTV). By a wide margin, skin scarification provided the greatest protection. Humoral immunity and resident-memory T cells notwithstanding, several approaches revealed that circulating, memory CD8(+) T cells primed via scarification were functionally superior and conferred enhanced virus control.

MyD88-dependent immunity to a natural model of vaccinia virus infection does not involve Toll-like receptor 2.

Unlabelled: Although the pattern recognition receptor Toll-like receptor 2 (TLR2) is typically thought to recognize bacterial components, it has been described to alter the induction of both innate and adaptive immunity to a number of viruses, including vaccinia virus (VACV). However, many pathogens that reportedly encode TLR2 agonists may actually be artifactually contaminated during preparation, possibly with cellular debris or merely with molecules that sensitize cells to be activated by authentic TLR2 agonists. In both humans and mice, the most relevant natural route of infection with VACV is through intradermal infection of the skin.

Recombinant poxviruses: versatile tools for immunological assays.

The study of antigen processing and presentation is critical to our understanding of the mechanisms that govern immune surveillance. A typical requirement of assays designed to examine antigen processing and presentation is the de novo biosynthesis of a model antigen. Historically, Vaccinia virus (VACV), a poxvirus closely related to Cowpox, has enjoyed widespread use for this purpose.

Perforin-dependent CD4+ T-cell cytotoxicity contributes to control a murine poxvirus infection.

CD4(+) T cells are generally regarded as helpers and regulators of the immune response. Although cytolytic CD4(+) T cells have been described, whether those generated during the course of a viral infection play a role in virus control remains unknown. Here we show that during acute infection with ectromelia virus, the mouse homolog of the human virus of smallpox, large numbers of CD4(+) T cells in the draining lymph node and liver of resistant mice have a cytotoxic phenotype.

Comparable polyfunctionality of ectromelia virus- and vaccinia virus-specific murine T cells despite markedly different in vivo replication and pathogenicity.

Vaccinia virus (VACV) stimulates long-term immunity against highly pathogenic orthopoxvirus infection of humans (smallpox) and mice (mousepox [ectromelia virus {ECTV}]) despite the lack of a natural host-pathogen relationship with either of these species. Previous research revealed that VACV is able to induce polyfunctional CD8(+) T-cell responses after immunization of humans. However, the degree to which the functional profile of T cells induced by VACV is similar to that generated during natural poxvirus infection remains unknown.

Functional macroautophagy induction by influenza A virus without a contribution to major histocompatibility complex class II-restricted presentation.

Major histocompatibility complex (MHC) class II-presented peptides can be derived from both exogenous (extracellular) and endogenous (biosynthesized) sources of antigen. Although several endogenous antigen-processing pathways have been reported, little is known about their relative contributions to global CD4(+) T cell responses against complex antigens. Using influenza virus for this purpose, we assessed the role of macroautophagy, a process in which cytosolic proteins are delivered to the lysosome by de novo vesicle formation and membrane fusion.

Bordetella bronchiseptica modulates macrophage phenotype leading to the inhibition of CD4+ T cell proliferation and the initiation of a Th17 immune response.

Bordetella bronchiseptica is a Gram-negative bacterium equipped with several colonization factors that allow it to establish a persistent infection of the murine respiratory tract. Previous studies indicate that B. bronchiseptica adenylate cyclase toxin (ACT) and the type III secretion system (TTSS) synergize to drive dendritic cells into an altered phenotype to down-regulate the host immune response.