Diagnosis and Molecular Characterization of Chikungunya Virus Infections

In recent years, large-scale outbreaks of chikungunya arbovirus (CHIKV), which is transmitted by the Aedes mosquito, have enabled the rapid propagation of the virus across the world. After acute infection phase with commonly fever, joint pain, headache, or rash, chronic rheumatism (arthralgia or myalgia, anorexia, and concentration disorders) up to 40% of cases is observed. The chronic form is defined by symptoms persisting for more than 3 months, and up to years, after initial diagnosis. Chronic discomfort has been linked to one of the four genotypes described. These genotypes represent different geographic lineages (classification based on partial sequence of viral E1 glycoprotein): West African, East-Central-South-African (ECSA), ECSA-diverged or Indian Ocean Lineage (IOL), and Asian. The first marker detected in CHIK infection is the viral RNA, usually by reverse transcription-polymerase chain reaction (RT-PCR). This marker can be identified in samples within 8 days of symptom onset. The infection can also be diagnosed with serological testing to detect CHIKV-specific immunoglobulin IgG and/or IgM. Sequencing studies can determine the infecting genotype

Enhanced detection of viral RNA species using fokI-assisted digestion of DNA duplexes and DNA/RNA hybrids

The accurate detection of nucleic acids from certain biological pathogens is critical for the diagnosis of human diseases. However, amplified detection of RNA molecules from a complex sample by direct detection of RNA/DNA hybrids remains a challenge. Here, we show that type IIS endonuclease FokI is able to digest DNA duplexes and DNA/RNA hybrids when assisted by a dumbbell-like fluorescent sensing oligonucleotide. As proof of concept, we designed a battery of sensing oligonucleotides against specific regions of the SARS-CoV-2 genome and interrogated the role of FokI relaxation as a potential nicking enzyme for fluorescence signal amplification. FokI-assisted digestion of SARS-CoV-2 probes increases the detection signal of ssDNA and RNA molecules and decreases the limit of detection more than 3.5-fold as compared to conventional molecular beacon approaches. This cleavage reaction is highly specific to its target molecules, and no detection of other highly related B-coronaviruses was observed in the presence of complex RNA mixtures. In addition, the FokI-assisted reaction has a high multiplexing potential, as the combined detection of different viral RNAs, including different SARS-CoV-2 variants, was achieved in the presence of multiple combinations of fluorophores and sensing oligonucleotides. When combined with isothermal rolling circle amplification technologies, FokI-assisted digestion reduced the detection time of SARS-CoV-2 in COVID-19-positive human samples with adequate sensitivity and specificity compared to conventional reverse transcription polymerase chain reaction approaches, highlighting the potential of FokI-assisted signal amplification as a valuable sensing mechanism for the detection of human pathogens.Funding was provided by the ISCIII (COV00624 to J.R.T. andM.F.F., PI18/01527 and PI21/01067 to M.F.F.), CSIC (202020E092 to M.F.F), the European Commission NextGenerationEU, through CSIC’s Global Health Platform (PTI Salud Global) and the Spanish Ministry of Science and Innovation through the Recovery, Transformation and Resilience Plan (GL2021-03-39 and GL2021-03-040), the PCTI from the Asturias Government, co-funded by 2018−2022/FEDER (IDI/2018/146 to M.F.F.), the AECC (PROYE18061FERN to M.F.F), ISPA-Janssen (048-Intramural Nov-Tevar to J.R.T.) and the IUOPA. J.R.T is supported by a JdC fellowship from the Spanish Ministry of Science and Innovation (IJC2018-36825-I). R.F.P. and P.S.O. are supported by the Severo Ochoa program (BP17-114 and BP17-165). A.P. is supported by the PFIS program (ISCIII, FI19/ 00085). J.J.A.L. is supported by the AECC fellowship. C.M. and V.L. are supported by IUOPA, and R.G.U. is supported by CIBERER.Peer reviewe

Detection and quantification of Merkel cell polyomavirus. Analysis of Merkel cell carcinoma cases from 1977 to 2015

This study investigates the presence of Merkel cell polyomavirus (MCPyV) in skin lesions of patients with Merkel cell carcinoma (MCC). MCPyV was quantified using quantitative Real-Time-PCR (qRT-PCR) in 34 paraffinized MCC samples (resected/biopsied) originally taken between 1977 and 2015, and six non-MCC samples. In 31 (91.2%) MCC-individuals, MCPyV was detected. No virus was observed in any non-MCC tumor. Average age at diagnosis was 78.2 ± 9.35 (55-97) years for women (n = 19) and 69.5 ± 14.7 (45-91) for men (n = 15) (P = 0.04). MCC tumor location, known in 25 cases, was: 11 (44%) in the head region, 6 (24%) in upper limbs, 4 (16%) in lower limbs, and 4 (16%) in the trunk. All but one patient had received some sort of treatment: 15 (45.45%) underwent both radio and chemotherapy, 13 (39.39%) only surgery, 2 (6.06%) surgery, plus radio and chemotherapy, 2 (6.06%) surgery and chemotherapy, and 1 (3.03%) only radiotherapy. Follow up data were available for 21/34 patients: recurrence was recorded for 4 (19.04%), and metastasis for 13 (61.9%). Recorded data showed that 10 men and 5 women (total 44.1%) died during follow up, 7 (46.7%) of them within 2 years of diagnosis. Viral load was 5.8 ± 1.4 log copies/10 cells (3.1-8.6), independent of any variable. MCPyV was very frequent in MCC. It was principally associated with head and limb tumors, it more commonly affected men, who in this study were, on average, younger than women, and had high rates of recurrence and mortality. The amplification techniques described here are easily applied and suitable for detecting the presence of MCPyV virus in MCC

Concordance between diagnostic tests.

<p>Concordance between diagnostic tests.</p

Comparison of average <i>H</i>. <i>pylori</i> DNA between different diagnostic tests.

<p>Comparison of average <i>H</i>. <i>pylori</i> DNA between different diagnostic tests.</p

Relationship between average <i>H</i>. <i>pylori</i> bacterial load and endoscopic findings, sex and age.

<p>Relationship between average <i>H</i>. <i>pylori</i> bacterial load and endoscopic findings, sex and age.</p

Nucleotide sequences of primers and probes.

<p>Nucleotide sequences of primers and probes.</p

Standard curve of H. pylori q-PCR assay.

<p>Standard curve of H. pylori q-PCR assay.</p

Percentage of biopsies testing positive for <i>H</i>. <i>pylori</i>.

<p>Percentage of biopsies testing positive for <i>H</i>. <i>pylori</i>.</p