Highly Multiplex Real-Time PCR–Based Screening for Blood-Borne Pathogens on an OpenArray Platform

Surveillance of wild animals carrying infectious agents based on high-throughput screening platform in the Republic of Korea

BACKGROUND

Infectious diseases transmitted by wild animals are major threats to public health. This study aimed to investigate the potential of rescued wild animals that died of unknown causes as reservoirs of infectious agents. From 2018 to 2019, 121 dead wild animals (55 birds and 66 mammals) were included in this study. All wild animals died during treatment after anthropogenic events. After deaths of animals, necropsies were performed and trachea, lungs, large intestine (including stool), and spleen were collected to determine causes of deaths. A high-throughput screening (HTS) quantitative polymerase chain reaction (qPCR) designed to detect 19 pathogens simultaneously against 48 samples in duplicate was performed using nucleic acids extracted from pooled tissues and peripheral blood samples. If positive, singleplex real-time PCR was performed for individual organs or blood samples.

RESULTS

The HTS qPCR showed positive results for Campylobacter jejuni (10/121, 8.3%), Campylobacter coli (1/121, 0.8%), Mycoplasma spp. (78/121, 64.5%), and Plasmodium spp. (7/121, 5.7%). Singleplex real-time PCR confirmed that C. jejuni was detected in the large intestine but not in the blood. C. coli was only detected in the large intestine. Mycoplasma spp. were detected in all organs, having the highest proportion in the large intestine and lowest in the blood. Plasmodium spp. was also detected in all organs, with proportions being were similar among organs.

CONCLUSIONS

This study shows that wild animals can become carriers of infectious agents without showing any clinical symptoms.

Immunogene expression analysis in betanodavirus infected-Senegalese sole using an OpenArray® platform

The transcriptomic response of Senegalese sole (Solea senegalensis) triggered by two betanodaviruses with different virulence to that fish species has been assessed using an OpenArray® platform based on TaqMan™ quantitative PCR. The transcription of 112 genes per sample has been evaluated at two sampling times in two organs (head kidney and eye/brain-pooled samples). Those genes were involved in several roles or pathways, such as viral recognition, regulation of type I (IFN-1)-dependent immune responses, JAK-STAT cascade, interferon stimulated genes, protein ubiquitination, virus responsive genes, complement system, inflammatory response, other immune system effectors, regulation of T-cell proliferation, and proteolysis and apoptosis. The highly virulent isolate, wSs160.3, a wild type reassortant containing a RGNNV-type RNA1 and a SJNNV-type RNA2 segments, induced the expression of a higher number of genes in both tested organs than the moderately virulent strain, a recombinant harbouring mutations in the protruding domain of the capsid protein. The number of differentially expressed genes was higher 2 days after the infection with the wild type isolate than at 3 days post-inoculation. The wild type isolate also elicited an exacerbated interferon 1 response, which, instead of protecting sole against the infection, increases the disease severity by the induction of apoptosis and inflammation-derived immunopathology, although inflammation seems to be modulated by the complement system. Furthermore, results derived from this study suggest a potential important role for some genes with high expression after infection with the highly virulent virus, such as rtp3, sacs and isg15. On the other hand, the infection with the mutant does not induce immune response, probably due to an altered recognition by the host, which is supported by a different viral recognition pathway, involving myd88 and tbkbp1.

Fecal indicator bacteria, fecal source tracking markers, and pathogens detected in two Hudson River tributaries

Volunteer monitoring in the Hudson River watershed since 2012 has identified that the Wallkill River and Rondout Creek tributary complex have elevated concentrations of the fecal indicator bacteria, enterococci. Concentrations of enterococci do not provide insight into the sources of pollution and are imperfect indicators of health risks. In 2017, the regular monthly volunteer monitoring campaign for culturable enterococci at 24 sites on the Wallkill and Rondout expanded to include: (1) culturable measurements of E. coli and quantification of E. coli and Enterococcus specific markers vis nanoscale qPCR, (2) microbial source tracking (MST) assays (avian, human, bovine, and equine) via real time PCR and nanoscale qPCR, and 3) quantification of 12 gastrointestinal pathogens including viruses, bacteria, and protozoa via nanoscale qPCR. Three human associated MST markers (HumM2, HF183, and B. theta) corroborated that human pollution was present in Rondout Creek and widespread in the Wallkill River. The presence of B. theta was associated with increased concentrations of culturable E. coli. Genes for adenovirus 40 and 41 conserved region, rotavirus A NSP3, E. coli eae and stx1, and Giardia lamblia 18S rRNA were detected in >45% of samples. Abundance of rotavirus A NSP3 genes was significantly correlated to the bovine marker gene, CowM3, though wild bird sources cannot be ruled out. This is the first study to investigate potential fecal pollution sources and pathogen concentrations in Hudson tributaries during the months of peak recreational use.

The use of laser-based diagnostics for the rapid identification of infectious agents in human blood

AIMS

To investigate the use of a laser-based method of detection as a potential diagnostic test for the rapid identification of infectious agents in human blood.

METHODS AND RESULTS

In this study, the successful differentiation of blood spiked with viruses, bacteria or protozoan parasites to clinically relevant levels is demonstrated using six blood types (O+, O-, AB+, A+, A-, B+) using blood from different individuals with blood samples prepared in two different laboratories. Experiments were performed using various compositions of filters, experimental set-ups and experimental parameters for spectral capture.

CONCLUSIONS

The potential for developing a laser-based diagnostic instrument to detect the presence of parasites, bacteria and viruses in human blood capable of providing analysis results within minutes was demonstrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

There is an ongoing need for clinical diagnostics to adapt to newly emerging agents and to screen simultaneously for multiple infectious agents. A laser-based approach can achieve sensitive, multiplex detection with minimal sample preparation and provide rapid results (within minutes). These properties along with the flexibility to add new agent detection by simply adjusting the detection programming make it a promising tool for clinical diagnosis.

An Innovative Multiplexed and Flexible Molecular Approach for the Differential Detection of Arboviruses

Nucleic acid testing during the preseroconversion viremic phase is required to differentially diagnose arboviral infections. The continuing emergence of arboviruses, such as Zika virus (ZIKV), dengue virus (DENV), and chikungunya virus (CHIKV), necessitates the development of a flexible diagnostic approach. Similar clinical signs and the priority to protect pregnant women from ZIKV infection indicate that the differential diagnosis of arboviruses is essential for effective patient management, clinical care, and epidemiologic surveillance. We describe an innovative diagnostic approach that combines generic RT-PCR amplification and identification by hybridization to specific probes. Original tetrathiolated probes were designed for the robust, sensitive, and specific detection of amplified arboviral genomes. The limit of detection using cultured and quantified stocks of whole viruses was 1 TCID₅₀/mL for DENV-1, DENV-3, and CHIKV and 10 TCID₅₀/mL for DENV-2, DENV-4, and ZIKV. The assay had 100% specificity with no false-positive results. The approach was evaluated using 179 human samples that previously tested as positive for the presence of ZIKV, DENV, or CHIKV genomes. Accordingly, the diagnostic sensitivity for ZIKV, DENV, and CHIKV was 87.88% (n = 58/66), 96.67% (n = 58/60), and 94.34% (n = 50/53), respectively. This method could be easily adapted to include additional molecular targets. Moreover, this approach may also be adapted to develop highly specific, sensitive, and easy to handle platforms dedicated to the multiplex screening and identification of emerging viruses.

Point-of-Care Devices Using Disease Biomarkers To Diagnose Neurodegenerative Disorders

Neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases are highly prevalent and immensely destructive to the health and well-being of individuals and their families across the globe. Neurodegenerative diseases are characterized by the gradual loss of neural tissue in the central nervous system. Clearly, early diagnosis of the onset of neurodegeneration is vital and beneficial. Current diagnostic methods rely heavily on symptoms or autopsy results, thus overlooking early diagnosis, the only opportunity for amelioration. However, appropriately selected and used biomarker diagnostics provide a solution. This article reviews the development and application of biomarker-related diagnostics for neurodegenerative disease with specific recommendations for point-of-care (POC) methodology. These advantageous approaches may offer a solution to existing obstacles and limitations to neurodegenerative disease treatment.