Multiplex Immunoassay Approaches Using Luminex® xMAP® Technology for the Study of COVID-19 Disease.

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has been one of the most severe outbreaks of respiratory illness in history. The clinical symptoms of COVID-19 may be similar to flu, although they can be life-threatening, particularly in the elderly and immunocompromised population. Together with nucleic acid detection, serological testing has been essential for the diagnosis of SARS-CoV-2 infection but has been critically important for studying the epidemiology, serosurveillance, and for vaccine research and development. Multiplexed immunoassay technologies have a particular advantage as they can simultaneously measure multiple analytes from a single sample. xMAP technology is a multiplex analysis platform that can measure up to 500 analytes at the same time from the same sample. It has been shown to be an important tool for studying immune response to the various SARS-CoV-2 antigens, as well as for measuring host protein biomarker levels as prognostic indicators of COVID-19. In this chapter, we describe several key studies where xMAP technology was used for multiplexed analysis of SARS-COV-2 antibody responses and host protein expression in COVID-19 patients.

Diverse Trichomonas lineages in Australasian pigeons and doves support a columbid origin for the genus Trichomonas.

Trichomonas is a significant protist genus, and includes T. vaginalis, the most prevalent sexually transmitted non-viral infection of humans, and T. gallinae of rock doves (Columba livia), one of the earliest known avian pathogens. New Trichomonas genotypes, including T. vaginalis-like isolates, have been discovered in American columbid hosts, suggesting geographically widespread cryptic diversity of Trichomonas in pigeons and doves. We sampled 319 birds from 22 columbid species in Australia, Papua New Guinea, New Zealand and southern Africa and uncovered 15 novel lineages of Trichomonas, more than doubling the known diversity of this parasite genus and providing evidence for frequent host-switching that eventually gave rise to T. vaginalis in humans. We show that Trichomonas has a columbid origin and likely underwent Miocene expansion out of Australasia. Our chronological topology for Trichomonas is calibrated on the evolution of a host phenotypic trait associated with ecological entrapment of the most basal extant lineage of Trichomonas in Ptilinopus fruit-doves.

Performance Evaluation of the Luminex Aries C. difficile Assay in Comparison to Two Other Molecular Assays within a Multihospital Health Care Center.

Clostridioides difficile infection (CDI) remain a serious issue in the United States. Fast and accurate diagnosis of CDI is paramount to achieve immediate infection control initiation, triaging, and isolation, as well as appropriate antibiotic treatment. However, both, over- and underdiagnosis can lead to adverse patient outcomes, such as unnecessary administration of antibiotics or unwanted spread of spores in any hospital setting, respectively. In this prospective study, we evaluated the FDA-cleared Aries C. difficile assay and compared its performance and workflow characteristics to those of the BD Max Cdiff and Xpert C. difficile/Epi assays. Out of 302 samples tested, 55 (18.2%) samples were positive, and 234 (77.5%) samples were negative for C. difficile by all three testing methods. Comparison results showed a positive and negative percent agreement (PPA and NPA, respectively) between the Aries and Xpert assays of 95.2% (59/62) and 99.2% (238/240), respectively. The PPA and NPA between the Aries and BD Max assays were 91.8% (56/61) and 96.6% (230/238), respectively. Invalid result rates were determined to be 2.6% for the BD Max assay, 1.0% for the Aries assay, and 0% for the Xpert assay. Hands-on time (HoT) and total turnaround time (TAT) varied considerably depending on the sample number and instrument throughput. The HoT ranged from 1.2 to 3.5 min per sample, and the TAT was 1 to 2.3 h. Overall, the results demonstrated that the Aries assay is a rapid and sensitive method for the diagnosis of CDI in clinical laboratories.

Evaluation of the Aries Bordetella Assay for Detection and Identification of Bordetella pertussis in Nasopharyngeal Swab Specimens.

The Aries Bordetella assay (Aries BA) (Luminex Corporation) recently received FDA clearance for the detection and differentiation of Bordetella pertussis and Bordetella parapertussis nucleic acids in nasopharyngeal swab (NPS) samples. The objective of this study was to evaluate the performance of the Aries BA in comparison to that of the BioFire FilmArray respiratory panel (RP). The Aries BA was evaluated using retrospective, remnant nasopharyngeal swabs (NPS), previously tested by FilmArray RP. Performance characteristics evaluated included positive percent agreement (PPA) and negative percent agreement (NPA) with the FilmArray RP. Discordant analysis was performed using bidirectional sequencing. A time and motion study was performed to compare the laboratory workflow of the two tests. Three hundred samples were included in the study. There were no samples positive for B. parapertussis The PPA and NPA of the Aries BA were 61.1% (95% confidence interval [CI], 35.8 to 82.7%) and 100% (95% CI, 98.7 to 100%). Discordant results included five Bordetella bronchiseptica results that were incorrectly identified as B. pertussis by the FilmArray RP and one false-negative result for both the Aries BA and the FilmArray RP. The overall agreement between the Aries BA and FilmArray RP for the detection of B. pertussis was considered good at 97.7% with a kappa value of 0.71 (95% CI, 0.51 to 0.9). The Aries BA offers a new diagnostic option for the rapid and targeted approach to the diagnosis of pertussis. Unlike the FilmArray RP, the Aries BA did not cross-react with B. bronchiseptica in our study, although a larger sample set should be tested to confirm this finding.

Assessing circovirus gene flow in multiple spill-over events.

The establishment of viral pathogens in new host environments following spillover events probably requires adaptive changes within both the new host and pathogen. After many generations, signals for ancient cross-species transmission may become lost and a strictly host-adapted phylogeny may mimic true co-divergence while the virus may retain an inherent ability to jump host species. The mechanistic basis for such processes remains poorly understood. To study the dynamics of virus-host co-divergence and the arbitrary chances of spillover in various reservoir hosts with equal ecological opportunity, we examined structural constraints of capsid protein in extant populations of Beak and feather disease virus (BFDV) during known spillover events. By assessing reservoir-based genotype stratification, we identified co-divergence defying signatures in the evolution BFDV which highlighted primordial processes of cryptic host adaptation and competing forces of host co-divergence and cross-species transmission. We demonstrate that, despite extensive surface plasticity gathered over a longer span of evolution, structural constraints of the capsid protein allow opportunistic host switching in host-adapted populations. This study provides new insights into how small populations of endangered psittacine species may face multidirectional forces of infection from reservoirs with apparently co-diverging genotypes.

Pigeon circoviruses from feral pigeons in Australia demonstrate extensive recombination and genetic admixture with other circoviruses.

Like other avian circovirus species, Pigeon circovirus (PiCV) is known to be genetically diverse with a relatively small circular single-stranded DNA genome of 2 kb that encodes for a capsid protein (Cap) and a replication initiator protein (Rep). Recent paleoviral evidence hints towards a probable Gondwanan origin of avian circoviruses, paralleling the evolution and dispersal of their hosts. Limited availability of PiCV genome sequence data in Australia has hindered phylogeographic studies in this species, so we screened clinically normal rock doves (Columba livia) in regional New South Wales, and demonstrated a high prevalence (76%) of PiCV infection by PCR. We also recovered 12 complete novel PiCV genomes and phylogenetic analyses revealed that PiCV circulating in Australian feral pigeons formed two strongly supported monophyletic clades. One clade resided with PiCV genomes from Poland, Australia, United Kingdom, Belgium, China, and Japan, and another basal clade was more closely related to PiCV genomes from Poland. A novel more distantly-related PiCV rep gene formed a solitary clade with weak posterior support. So we further analysed all selected partial rep gene sequences to demonstrate a likely naturally occurring spillover infection from a passerine circovirus candidate. The findings suggest that there is a high degree of genetic variation within PiCV in Columbiformes with potential greater admixture between avian circoviruses within Australia than previously known. RESEARCH HIGHLIGHTS Confirmed high prevalence rate of PiCV circulating in Australian wild pigeons. Highlighted extensive recombination events within Australian PiCV. Demonstrated a likely naturally occurring spillover infection from a passerine circovirus candidate.

Genomic characterization of two novel pathogenic avipoxviruses isolated from pacific shearwaters (Ardenna spp.).

BACKGROUND: Over the past 20 years, many marine seabird populations have been gradually declining and the factors driving this ongoing deterioration are not always well understood. Avipoxvirus infections have been found in a wide range of bird species worldwide, however, very little is known about the disease ecology of avian poxviruses in seabirds. Here we present two novel avipoxviruses from pacific shearwaters (Ardenna spp), one from a Flesh-footed Shearwater (A. carneipes) (SWPV-1) and the other from a Wedge-tailed Shearwater (A. pacificus) (SWPV-2). RESULTS: Epidermal pox lesions, liver, and blood samples were examined from A. carneipes and A. pacificus of breeding colonies in eastern Australia. After histopathological confirmation of the disease, PCR screening was conducted for avipoxvirus, circovirus, reticuloendotheliosis virus, and fungal agents. Two samples that were PCR positive for poxvirus were further assessed by next generation sequencing, which yielded complete Shearwaterpox virus (SWPV) genomes from A. pacificus and A. carneipes, both showing the highest degree of similarity with Canarypox virus (98% and 67%, respectively). The novel SWPV-1 complete genome from A. carneipes is missing 43 genes compared to CNPV and contains 4 predicted genes which are not found in any other poxvirus, whilst, SWPV-2 complete genome was deemed to be missing 18 genes compared to CNPV and a further 15 genes significantly fragmented as to probably cause them to be non-functional. CONCLUSION: These are the first avipoxvirus complete genome sequences that infect marine seabirds. In the comparison of SWPV-1 and -2 to existing avipoxvirus sequences, our results indicate that the SWPV complete genome from A. carneipes (SWPV-1) described here is not closely related to any other avipoxvirus genome isolated from avian or other natural host species, and that it likely should be considered a separate species.

Evolution of circoviruses in lorikeets lags behind its hosts.

The presence of endogenous viral elements in host genomes hints towards much older host-virus relationships than predicted by exogenous phylogenies, with highly mutable single-stranded DNA (ssDNA) viruses and RNA viruses often occupying entangled multispecies ecological niches. The difficulty lies in unravelling the long-term evolutionary history of vertebrate virus-host relationships and determining the age of a potentially ancient tree based only fresh shoots at the tips. Resolving such lineages, and the sometimes great discrepancy amongst evolutionary timescales, is problematic, especially when purifying selection or recombination can significantly alter the accuracy of phylogenetic reconstruction methods. Pathogens which occupy entangled multispecies ecological niches add a further layer of complexity but we show that multi-host scenarios may also provide opportunities to identify allopatric or sympatric paleobiological signals that can unlock longer term phylogenies. We identified host-based, cryptic, sympatric differentiation in beak and feather disease virus in the Psittaciformes tribe Loriini along with endogenous circovirus motifs in Kea (Nestor notabilis) and Gondwanan vicariance estimates to infer the evolutionary timescale of the circoviruses. This demonstrated a chronology of psittacine circovirus speciation aligned to conservative Zealandic divergences for relic circovirus motifs in Kea and a 10million year divergence coinciding with the Papuan central range orogeny that triggered the radiation of Loriini and segregation of an antecedent viral clade in Australian lorikeets. Estimates of circovirus speciation in birds highlighted a Gondwanan dominant group in Neoaves with passerine, columbid and larid circoviruses deeply separated from those in waterfowl, consistent with a Triassic divergence of Galloanserae. The circovirus tree had a deep ancestry in invertebrates with a Palaeozoic expansion in fish and mammals. We show that longer term evolutionary relationships in viruses which have a high rate of mutation and admixture can be disentangled, highlighting that contemporary virus host-switching can be explained by deep intra-lineage host phylogeny.

Recombinantly expressed virus-like particles (VLPs) of canine circovirus for development of an indirect ELISA.

Canine circovirus (CanineCV) is an emerging pathogen in domestic dogs, detected in multiple countries in association with varying clinical and pathological presentations including diarrhoea, vasculitis, granulomatous inflammation, and respiratory signs. Understanding the pathology of CanineCV is confounded by the fact that it has been detected in asymptomatic dogs as well as in diseased dogs concurrently infected with known pathogens. Recombinantly expressed self-assembling Virus-like particles (VLPs) lack viral genomic material but imitate the capsid surface conformations of wild type virion, allowing arrays of biological applications including subunit vaccine development and immunodiagnostics. In this study, full length CanineCV capsid gene was expressed in Escherichia coli followed by two-step purification process to yield soluble capsid protein in high concentration. Transmission electron microscopy (TEM) confirmed the capsid antigen self-assembled into 17-20 nm VLPs in glutathione S-transferase (GST) buffer, later utilised to develop an indirect enzyme-linked immunosorbent assay (iELISA). The respective sensitivity and specificity of the proposed iELISA were 94.10% and 88.40% compared with those obtained from Western blot. The mean OD450 value for western blot positive samples was 1.22 (range 0.12-3.39) and negative samples was 0.21 (range 0.07-0.41). An optimal OD450 cut-off of 0.35 was determined by ROC curve analysis. Median inter-assay and intra-assay validation revealed that the iELISA test results were reproducible with coefficients of variation 7.70 (range 5.6-11.9) and 4.21 (range 1.2-7.4). Our results demonstrated that VLP-based iELISA is a highly sensitive method for serological diagnosis of CanineCV infections in dogs, suitable for large-scale epidemiological studies.

Beak and feather disease virus detected in the endangered Red Goshawk (Erythrotriorchis radiatus).

We report the first detection and prevalence of Beak and feather disease virus (BFDV) in Australia's Red Goshawk (Erythrotriorchis radiatus). This is a new host for this pervasive pathogen amongst a growing list of non-psittacine species including birds of prey from the orders Accipitriformes (hawks, eagles, kites), Falconiformes (falcons and caracas), and Strigiformes (owls). The Red Goshawk is the first non-psittacine species listed as Endangered to be diagnosed with BFDV. We report an initial case of infection discovered post-mortem in a dead nestling and subsequent surveillance of birds from across northern Australia. We reveal BFDV prevalence rates in a wild raptor population for the first time, with detections in 25% (n = 7/28) of Red Goshawks sampled. Prevalence appears higher in juveniles compared to adults, although not statistically significant, but is consistent with studies of wild psittacines. BFDV genotypes were associated with the Loriinae (lorikeets, budgerigar, and fig parrots), Cacatuini (Cockatoos), and Polytelini (long-tailed parrots) tribes; species which are preyed upon by Red Goshawks. A positive BFDV status may be associated with lower body mass but small sample sizes precluded robust statistical analysis. We postulate the possible impacts of the virus on Red Goshawks and discuss future research priorities given these preliminary observations.

Complete genome constellation of a dominant Bovine rotavirus genotype circulating in Bangladesh reveals NSP4 intragenic recombination with human strains.

Rotavirus A is a leading cause of non-bacterial gastroenteritis in humans and domesticated animals. Despite the vast diversity of bovine Rotavirus A strains documented in South Asian countries, there are very few whole genomes available for phylogenetic study. A cross-sectional study identified a high prevalence of the G6P[11] genotype of bovine Rotavirus A circulating in the commercial cattle population in Bangladesh. Next-generation sequencing and downstream phylogenetic analysis unveiled all 11 complete gene segments of this strain (BD_ROTA_CVASU), classifying it under the genomic constellation G6P[11]-I2-R2-C2-M2-A13-N2-T6-E2-H3, which belongs to a classical DS-1-like genomic backbone. We found strong evidence of intragenic recombination between human and bovine strains in the Non-structural protein 4 (NSP4) gene, which encodes a multifunctional enterotoxin. Our analyses highlight frequent zoonotic transmissions of rotaviruses in diverse human-animal interfaces, which might have contributed to the evolution and pathogenesis of this dominant genotype circulating in the commercial cattle population in Bangladesh.

Novel pathogenic adenovirus in Timneh grey parrot (Psittacus timneh) unveils distinct lineage within Aviadenovirus.

Wild birds harbour a vast diversity of adenoviruses that remain uncharacterised with respect to their genome organisation and evolutionary relatedness within complex host ecosystems. Here, we characterise a novel adenovirus type within Aviadenovirus genus associated with severe necrotising hepatitis in a captive Timneh grey parrot, tentatively named as Timneh grey parrot adenovirus 1 (TpAdV-1). The TpAdV-1 genome is 39,867 bp and encodes 46 putative genes with seven hitherto not described ones. Comparative genomics and phylogenetic analyses revealed highest nucleotide identity with psittacine adenovirus 1 and psittacine adenovirus 4 that formed a discrete monophyletic clade within Aviadenovirus lineage suggesting a deep host co-divergent lineage within Psittaciformes hosts. Several recombination breakpoints were identified within the TpAdV-1 genome, which highlighted an ancient evolutionary relationship across the genera Aviadenovirus, Mastadenovirus and Atadenovirus. This study hints towards a host-adapted sub-lineage of avian adenovirus capable of having significant host virulence in Psittaciformes birds augmented with ecological opportunity.

Lesions and viral loads in racing pigeons naturally coinfected with pigeon circovirus and columbid alphaherpesvirus 1 in Australia.

Columbid alphaherpesvirus 1 (CoHV1) is associated with oral or upper respiratory tract lesions, encephalitis, and occasional fatal systemic disease in naive or immunosuppressed pigeons. Clinical disease is often reported with CoHV1 and coinfecting viruses, including pigeon circovirus (PiCV), which may cause host immunosuppression and augment lesion development. A natural outbreak of CoHV1 and PiCV coinfection occurred in a flock of 60 racing rock pigeons (Columba livia), in which 4 pigeons succumbed within 7 d of clinical onset. Lesions included suppurative stomatitis, pharyngitis, cloacitis, meningitis, and tympanitis, with eosinophilic intranuclear inclusion bodies consistent with herpesviral infection. In addition, large numbers of botryoid intracytoplasmic inclusion bodies were present in the skin, oral mucosa, and bursa of Fabricius, suggestive of circoviral infection, which was confirmed by immunohistochemistry. The concurrent viral load of CoHV1 and PiCV was high in liver, oropharynx, and bursa of Fabricius. We found PiCV in oro-cloacal swabs from 44 of 46 additional birds of variable clinical status, PiCV alone in 23 birds, and coinfection with CoHV1 in 21 birds. Viral copy numbers were significantly higher (p < 0.0001) for both viruses in clinically affected pigeons than in subclinical qPCR-positive birds. The CoHV1-induced lesions might have been exacerbated by concomitant PiCV infection.

Visualizing neutrophil extracellular traps in septic equine synovial and peritoneal fluid samples using immunofluorescence microscopy.

Septic synovitis and peritonitis are routinely diagnosed in horses based on clinical examination findings and laboratory assessment of synoviocentesis and abdominocentesis samples, respectively. Diagnosis is difficult in some cases because of an overlap in laboratory results for septic and non-septic inflammation. Neutrophil extracellular trap (NET) formation is part of the innate immune response against pathogens. Identifying and quantifying NETs, which have not been explored in clinical samples from horses with septic synovitis and peritonitis, to our knowledge, may be helpful in detecting infectious processes. Our main objective was to determine whether NETs could be visualized in septic equine synovial and peritoneal fluid cytology samples using immunofluorescence with antibodies against citrullinated histone H3 (Cit-H3) and myeloperoxidase (MPO). We analyzed 9 synovial and 4 peritoneal fluid samples. NET percentages were quantified using a simple counting technique, which is suitable for high-quality, well-preserved, and stained cytospin smears. NETs were evident in all septic samples and were absent in a non-septic sample; NETs were better visualized with Cit-H3 than with MPO immunolabeling. Overall, we believe that there is the potential for NETs and associated markers to be used to investigate and understand septic inflammation in horses.

Australasian Pigeon Circoviruses Demonstrate Natural Spillover Infection.

Pigeon circovirus (PiCV) is considered to be genetically diverse, with a relatively small circular single-stranded DNA genome of 2 kb that encodes for a capsid protein (Cap) and a replication initiator protein (Rep). Australasia is known to be the origin of diverse species of the Order Columbiformes, but limited data on the PiCV genome sequence has hindered phylogeographic studies in this species. To fill this gap, this study was conducted to investigate PiCV in 118 characteristic samples from different birds across Australia using PCR and sequencing. Eighteen partial PiCV Rep sequences and one complete PiCV genome sequence were recovered from reservoir and aberrant hosts. Phylogenetic analyses revealed that PiCV circulating in Australia was scattered across three different subclades. Importantly, one subclade dominated within the PiCV sequenced from Australia and Poland, whereas other PiCV sequenced in this study were more closely related to the PiCV sequenced from China, USA and Japan. In addition, PiCV Rep sequences obtained from clinically affected plumed whistling duck, blue billed duck and Australian magpie demonstrated natural spillover of PiCV unveiled host generalist characteristics of the pigeon circovirus. These findings indicate that PiCV genomes circulating in Australia lack host adapted population structure but demonstrate natural spillover infection.

A Multicentre Epidemiologic Study of Sudden and Unexpected Death in Adult Cats and Dogs in Australia.

Sudden and unexpected death (SUD) is a common reason for animals to undergo post-mortem examination. There is limited literature examining the causes of SUD in cats and dogs, and no research specific to Australia. The purpose of this study was to investigate the epidemiology and pathology of SUD in cats and dogs in a multicentric study across Australia. Retrospective post-mortem reports of SUD in cats and dogs were obtained from four veterinary schools in Australia distributed across four states. The frequency of SUD between institutes ranged from 2.1% to 6.5%. Dogs composed the majority of the study population (76%), and males outnumbered females, particularly in the feline subpopulation. After necropsy, 37% of SUD remained cause unknown, the largest category in both cats and dogs. When cause was identified, cardiovascular disease was most common in both species, followed by gastrointestinal disease in dogs, and trauma in cats. In dogs, multinomial logistic regression identified age as a risk factor significantly associated with the four largest categories of SUD. This study identified causes of SUD in Australian cats and dogs, including novel causes not previously reported. Further, this study revealed a higher rate of unsolved SUD in Australia than can be found in the literature from other countries.

High prevalence of ciprofloxacin resistance in Escherichia coli isolated from chickens, humans and the environment: An emerging one health issue.

The emergence of antimicrobial resistance in commensal bacteria poses a serious public health burden worldwide. Commensals can disseminate the resistance genes to pathogenic bacteria causing life-threatening infections. This cross-sectional study was designed to investigate the antimicrobial resistance pattern and molecular mechanism(s) of ciprofloxacin resistance in commensal E. coli from three major one health components (humans, animals and the environment) in Bangladesh. Samples were randomly collected from broiler chickens, broiler farm environments and hospitalized human patients from the same geographical area. Isolation and identification of E. coli were performed following standard bacteriological techniques. Antimicrobial susceptibility testing (AST) was performed by disk diffusion and broth microdilution methods. Mutation at the quinolone-resistance determining region (QRDR) was analyzed by sequencing. Of 450 samples, a total of 287 (63.8%; 95% CI 59.2-68.1%) E. coli strains was isolated, where 240 (83.6%; 95% CI 78.9-87.5%) strains were phenotypically resistant to ciprofloxacin. The prevalence of ciprofloxacin-resistant E. coli in broiler chicken, broiler farm environments and hospitalized human patients are 77.6%, 88.8% and 89% respectively. In AST against nine antimicrobials, all the isolates were found to be multidrug-resistant (MDR). The minimum inhibitory concentration (MIC) of ciprofloxacin was ranged from 4 to >128mg/L. Point mutations were detected in several sites of QRDR, specifically at 83 and 87 amino acid positions in gyrA gene, and 56, 57, 78, 80 and 84 amino acid positions in parC gene. Mutations resulted in amino acid substitutions. Phylogenetic analysis of gyrA and parC gene sequences showed a close relationship between the strains isolated from different sources. This study demonstrates a high prevalence of ciprofloxacin resistance in commensal E. coli in humans, animals and environment interface and their genealogically similarity poses an alarming public health consequence.

The COVID-19 Pandemic - A Diagnostic Industry Perspective.

The COVID-19 pandemic has brought about unprecedented changes to all facets of the healthcare system, including the diagnostic industry. The pandemic has highlighted both the challenges and strengths of the industry and has also provided valuable insights on how to be better prepared for future pandemics. In this perspective article, we describe the challenges faced by the diagnostic industry in general, particularly the difficulties encountered by Luminex Corporation, a diagnostic assay development and manufacturing company located in Austin, Texas, USA, as well as the mitigation strategies employed. In addition to discussion of the key challenges, the article provides insights on the lessons learned and steps that can be undertaken to better prepare for future outbreaks.

Diagnosis and Management of Bloodstream Infections With Rapid, Multiplexed Molecular Assays.

Bloodstream infection is a major health concern, responsible for considerable morbidity and mortality across the globe. Prompt identification of the responsible pathogen in the early stages of the disease allows clinicians to implement appropriate antibiotic therapy in a timelier manner. Rapid treatment with the correct antibiotic not only improves the chances of patient survival, but also significantly reduces the length of hospital stay and associated healthcare costs. Although culture has been the gold standard and most common method for diagnosis of bloodstream pathogens, it is being enhanced or supplanted with more advanced methods, including molecular tests that can reduce the turnaround time from several days to a few hours. In this article, we describe two rapid, molecular bloodstream infection panels that identify the most common pathogens and associated genetic determinants of antibiotic resistance - the Luminex® VERIGENE® Gram-Positive Blood Culture Test and the VERIGENE® Gram-Negative Blood Culture Test. We conducted a search on PubMed to retrieve articles describing the performance and impact of these tests in the clinical setting. From a total of 48 articles retrieved, we selected 15 for inclusion in this review based on the type and size of the study and so there would be minimum of three articles describing performance and three articles describing the impact post-implementation for each assay. Here we provide a comprehensive review of these publications illustrating the performance and clinical utility of these assays, demonstrating how genotypic tests can benefit diagnostic and antimicrobial stewardship efforts.

Detection of IgG Antibodies to SARS-CoV-2 and Neutralizing Capabilities Using the Luminex® xMAP® SARS-CoV-2 Multi-Antigen IgG Assay.

Serological assays have been a useful tool for detection of antibodies to SARS-CoV-2 during the COVID-19 pandemic. These assays are used for epidemiology and serosurveillance to monitor the progression of the pandemic, to identify and differentiate individuals who have developed antibodies from natural infection versus vaccine-induced immunity, and to identify potential donors of convalescent plasma for therapeutic purposes. In this chapter, we describe a commercially available bead-based serological assay, the Luminex® xMAP® SARS-CoV-2 Multi-Antigen IgG Assay, that detects and identifies antibodies against three SARS-CoV-2 antigens. In addition to the assay principle and workflow, we describe modifications that may be used to evaluate alternate sample types, antibody isotypes, and potential neutralizing antibody responses.