In pursuit of sensitivity: Lessons learned from viral nucleic acid detection and quantification on the Raindance ddPCR platform.

Sensitive PCR detection of viral nucleic acids plays a critical role in infectious disease research, diagnosis and monitoring. In the context of SARS-CoV-2 detection, recent reports indicate that digital PCR-based tests are significantly more sensitive than traditional qPCR tests. Numerous factors can influence digital PCR reaction sensitivity. In this review, using a model for human HIV infection and the Raindance ddPCR platform as an example, we describe technical aspects that contribute to sensitive viral signal detection in DNA and RNA from tissue samples, which often harbor viral reservoirs and serve as better predictors of disease outcome and indicators of treatment efficacy.

Ultrasensitive detection and quantification of viral nucleic acids with Raindance droplet digital PCR (ddPCR).

Sensitive detection of viral nucleic acids is critically important for diagnosis and monitoring of the progression of infectious diseases such as those caused by SARS-CoV2, HIV-1, and other viruses. In HIV-1 infection cases, assessing the efficacy of treatment interventions that are superimposed on combination antiretroviral therapy (cART) has benefited tremendously from the development of sensitive HIV-1 DNA and RNA quantitation assays. Simian immunodeficiency virus (SIV) infection of Rhesus macaques is similar in many key aspects to human HIV-1 infection and consequently this non-human primate (NHP) model has and continues to prove instrumental in evaluating HIV prevention, treatment and eradication approaches. Cell and tissue associated HIV-1 viral nucleic acids have been found to serve as useful predictors of disease outcome and indicators of treatment efficacy, highlighting the value of and the need for sensitive detection of viruses in cells/tissues from infected individuals or animal models. However, viral nucleic acid detection and quantitation in such sample sources can often be complicated by high nucleic acid input (that is required to detect ultralow level viruses in, for example, cure research) or inhibitors, leading to reduced detection sensitivity and under-quantification, and confounded result interpretation. Here, we present a step-by-step procedure to quantitatively recover cell/tissue associated viral DNA and RNA, using SIV-infected Rhesus macaque cells and tissues as model systems, and subsequently quantify the viral DNA and RNA with an ultrasensitive SIV droplet digital PCR (ddPCR) assay and reverse transcription ddPCR (RT-ddPCR) assay, respectively, on the Raindance ddPCR platform. The procedure can be readily adapted for a broad range of applications where highly sensitive nucleic acid detection and quantitation are required.

Role of the MicroRNAs in the Pathogenic Mechanism of Painful Symptoms in Long COVID: Systematic Review.

The ongoing pandemic of COVID-19 has caused more than 6.7 million tragic deaths, plus, a large percentage of people who survived it present a myriad of chronic symptoms that last for at least 6 months; this has been named as long COVID. Some of the most prevalent are painful symptoms like headache, joint pain, migraine, neuropathic-like pain, fatigue and myalgia. MicroRNAs are small non-coding RNAs that regulate genes, and their involvement in several pathologies has been extensively shown. A deregulation of miRNAs has been observed in patients with COVID-19. The objective of the present systematic review was to show the prevalence of chronic pain-like symptoms of patients with long COVID and based on the expression of miRNAs in patients with COVID-19, and to present a proposal on how they may be involved in the pathogenic mechanisms of chronic pain-like symptoms. A systematic review was carried out in online databases for original articles published between March 2020 to April 2022; the systematic review followed the PRISMA guidelines, and it was registered in PROSPERO with registration number CRD42022318992. A total of 22 articles were included for the evaluation of miRNAs and 20 regarding long COVID; the overall prevalence of pain-like symptoms was around 10 to 87%, plus, the miRNAs that were commonly up and downregulated were miR-21-5p, miR-29a,b,c-3p miR-92a,b-3p, miR-92b-5p, miR-126-3p, miR-150-5p, miR-155-5p, miR-200a, c-3p, miR-320a,b,c,d,e-3p, and miR-451a. The molecular pathways that we hypothesized to be modulated by these miRNAs are the IL-6/STAT3 proinflammatory axis and the compromise of the blood-nerve barrier; these two mechanisms could be associated with the prevalence of fatigue and chronic pain in the long COVID population, plus they could be novel pharmacological targets in order to reduce and prevent these symptoms.

Development of a reverse transcription droplet digital PCR (RT-ddPCR) assay for sensitive detection of simian immunodeficiency virus (SIV).

BACKGROUND: Simian immunodeficiency virus (SIV)-infected rhesus macaques constitute an excellent model of human HIV infection. Sensitive detection of SIV RNA in cell and tissue samples from infected animals subjected to treatment regimens becomes especially critical in determining which therapeutic attempts are successful, and consequently, which interventions should be prioritized in HIV cure research. RESULTS: In this report, we describe the design and testing of a Raindance ddPCR platform-based, sensitive SIV reverse transcription droplet digital PCR (RT-ddPCR) assay by exploring the combinations of various priming conditions and reverse transcriptases, and testing one-step vs. two-step procedures, to eliminate background signal(s) and enable detection and quantification of low level target signals. CONCLUSIONS: Similar reaction conditions and assay validation procedures can be explored for potential development of additional assays for other applications that require sensitive detection of low-level targets in RNA samples.

Genetic dissection of the phosphoinositide cycle in Drosophila photoreceptors.

Phototransduction in Drosophila is mediated by phospholipase C-dependent hydrolysis of PIP2-, and is an important model for phosphoinositide signalling. Although generally assumed to operate by generic machinery conserved from yeast to mammals, some key elements of the phosphoinositide cycle have yet to be identified in Drosophila photoreceptors. Here, we used transgenic flies expressing fluorescently tagged probes (P4M and TbR332H), which allow in vivo quantitative measurements of PI4P and PIP2 dynamics in photoreceptors of intact living flies. Using mutants and RNA interference for candidate genes potentially involved in phosphoinositide turnover, we identified Drosophila PI4KIIIα (CG10260) as the PI4-kinase responsible for PI4P synthesis in the photoreceptor membrane. Our results also indicate that PI4KIIIα activity requires rbo (the Drosophila orthologue of Efr3) and CG8325 (orthologue of YPP1), both of which are implicated as scaffolding proteins necessary for PI4KIIIα activity in yeast and mammals. However, our evidence indicates that the recently reported central role of dPIP5K59B (CG3682) in PIP2 synthesis in the rhabdomeres should be re-evaluated; although PIP2 resynthesis was suppressed by RNAi directed against dPIP5K59B, little or no defect was detected in a reportedly null mutant (dPIP5K18 ).

Evaluating the Intactness of Persistent Viral Genomes in Simian Immunodeficiency Virus-Infected Rhesus Macaques after Initiating Antiretroviral Therapy within One Year of Infection.

The major obstacle to more-definitive treatment for HIV infection is the early establishment of virus that persists despite long-term combination antiretroviral therapy (cART) and can cause recrudescent viremia if cART is interrupted. Previous studies of HIV DNA that persists despite cART indicated that only a small fraction of persistent viral sequences was intact. Experimental simian immunodeficiency virus (SIV) infections of nonhuman primates (NHPs) are essential models for testing interventions designed to reduce the viral reservoir. We studied the viral genomic integrity of virus that persists during cART under conditions typical of many NHP reservoir studies, specifically with cART started within 1 year postinfection and continued for at least 9 months. The fraction of persistent DNA in SIV-infected NHPs starting cART during acute or chronic infection was assessed with a multiamplicon, real-time PCR assay designed to analyze locations that are regularly spaced across the viral genome to maximize coverage (collectively referred to as "tile assay") combined with near-full-length (nFL) single-genome sequencing. The tile assay is used to rapidly screen for major deletions, with nFL sequence analysis used to identify additional potentially inactivating mutations. Peripheral blood mononuclear cells (PBMC) from animals started on cART within 1 month of infection, sampled at least 9 months after cART initiation, contained at least 80% intact genomes, whereas those from animals started on cART 1 year postinfection and treated for 1 year contained intact genomes only 47% of the time. The most common defect identified was large deletions, with the remaining defects caused by APOBEC-mediated mutations, frameshift mutations, and inactivating point mutations. Overall, this approach can be used to assess the intactness of persistent viral DNA in NHPs.IMPORTANCE Molecularly defining the viral reservoir that persists despite antiretroviral therapy and that can lead to rebound viremia if antiviral therapy is removed is critical for testing interventions aimed at reducing this reservoir. In HIV infection in humans with delayed treatment initiation and extended treatment duration, persistent viral DNA has been shown to be dominated by nonfunctional genomes. Using multiple real-time PCR assays across the genome combined with near-full-genome sequencing, we defined SIV genetic integrity after 9 to 18 months of combination antiretroviral therapy in rhesus macaques starting therapy within 1 year of infection. In the animals starting therapy within a month of infection, the vast majority of persistent DNA was intact and presumptively functional. Starting therapy within 1 year increased the nonintact fraction of persistent viral DNA. The approach described here allows rapid screening of viral intactness and is a valuable tool for assessing the efficacy of novel reservoir-reducing interventions.

Acute administration of levetiracetam in tonic pain model modulates gene expression of 5HT1A and 5HT7 receptors in the thalamus of rats (Rattus norvergicus).

The nociceptive effect of Levetiracetam (LEV) on the expression of 5-HT1A and 5-HT7 receptors found in the thalamus was evaluated. Thirty-six male rats (Wistar) were randomized into six groups: in the Control group without treatment; LEV50 group LEV was administered in a single dose of 50 mg/kg i.g.; in the LEV300 group LEV dose of 300 mg/kg i.g.; in the FORMALIN group the formalin test was performed; in the LEV50/FORMALIN group LEV dose of 50 mg/kg i.g and the formalin test was performed; in the LEV300/FORMALIN group LEV dose of 300 mg/kg i.g and the formalin test was performed, subsequently the thalamus was dissected in all groups. In the formalin tests LEV exhibited an antinociceptive effect in the LEV300/FORMALIN group (p < 0.05) and a pronociceptive effect in the LEV50/FORMALIN group (p < 0.001). The results obtained by Real-time PCR confirmed the expression of the 5-HT1A and 5-HT7 receptors in the thalamus, 5-HT1A receptors increased significantly in the FORMALIN group and the LEV300/FORMALIN group (p < 0.05). 5-HT7 receptors are only over expressed at a dose of 300 mg/Kg of LEV with formalin (p < 0.05). This suggests that LEV modulates the sensation of pain by controlling the expression of 5-HT1A and 5-HT7 in a tonic pain model, and that changes in the expression of 5-HT1A and 5-HT7 receptors are associated with the sensation of pain, furthermore its possibility to be used in clinical treatments for pain.

Chyle Leak Following Autologous Breast Reconstruction: A Rare Complication of a Deep Inferior Epigastric Artery Perforator Flap.

BACKGROUND: While complications of deep inferior epigastric artery perforator flaps are known and well documented, a thorough literature review revealed no other reports of a patient developing a chyle leak following the use of the internal mammary vessels for recipient vessels in autologous breast reconstruction. CASE: A 55-year-old woman underwent free autologous breast reconstruction. She developed a chyle leak during the postoperative period. This was verified through a computed tomography scan and fluid analysis demonstrating a high triglyceride count and the presence of chylomicrons. The leak resolved with conservative measures including compression and a low-fat, high-protein diet. DISCUSSION: The presence of chyle leak following dissection of the internal mammary vessels is a unique complication of autologous breast reconstruction. There have been reports of lymph leaks following mastectomy, but these are mostly reported in the axilla. A history of radiation to the contralateral breast and aberrant anatomy may have contributed to the complication. Treatment of chyle leaks ranges from conservative management to the use of total parenteral nutrition and somatostatin analogs to surgical intervention. CONCLUSION: While altering practice patterns based on a single case is not usually suggested, this complication does intimate that dealing with lymphatic vessels and lymph nodes in the chest should be done deliberately to prevent lymphatic leaks.

Ultrasound as a Useful Tool in the Diagnosis of Rheumatoid Arthritis in Patients With Undifferentiated Arthritis.

BACKGROUND: Nowadays, rheumatologists face challenges in finding an effective method to classify and treat patients with undifferentiated arthritis (UA). There is a need for new tools that could ensure accurate characterization of inflammatory processes in these patients. OBJECTIVE: The aim of this study was to investigate if a characterization of UA patients using ultrasound (US) may help to fulfill the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) rheumatoid arthritis (RA) classification criteria in a real-life cohort. METHODS: We conducted a cross-sectional study in 2 rheumatology care clinics. Patients not fulfilling the 2010 ACR/EULAR RA criteria were included. On the examination day, all patients underwent a physical examination, radiography, and US. The 7-joint US score was adopted to scan all patients. The US was performed according to EULAR criteria and interpreted by Outcome Measures in Rheumatology definitions. Gray-scale and power Doppler synovitis and tenosynovitis were scored. Bone erosions were also evaluated during the US examination. RESULTS: A total of 204 patients were included. The diagnosis was modified from UA to RA in 86 patients (42.1%). Also, the final score of the 2010 ACR/EULAR RA classification criteria changed from a mean of 4.6 to 6.5 after the US examination. In addition to synovitis, a wide range of tenosynovitis and bone erosions were detected by US. Synovitis was more frequently detected in second metacarpophalangeal joint followed by second metatarsophalangeal joint (MTPj) and fifth MTPj. The tendons of the wrist and second and third fingers were the most affected. In relation to bone erosions, second metacarpophalangeal joint and fifth MTPj were the joints with more proportion of anatomical damage. CONCLUSIONS: The US demonstrated to be useful to help accurately classify as RA patients previously diagnosed with UA.

Comparative mutational landscape analysis of patient-derived tumour xenografts.

BACKGROUND: Screening of patients for cancer-driving mutations is now used for cancer prognosis, remission scoring and treatment selection. Although recently emerged targeted next-generation sequencing-based approaches offer promising diagnostic capabilities, there are still limitations. There is a pressing clinical need for a well-validated, rapid, cost-effective mutation profiling system in patient specimens. Given their speed and cost-effectiveness, quantitative PCR mutation detection techniques are well suited for the clinical environment. The qBiomarker mutation PCR array has high sensitivity and shorter turnaround times compared with other methods. However, a direct comparison with existing viable alternatives are required to assess its true potential and limitations. METHODS: In this study, we evaluated a panel of 117 patient-derived tumour xenografts by the qBiomarker array and compared with other methods for mutation detection, including Ion AmpliSeq sequencing, whole-exome sequencing and droplet digital PCR. RESULTS: Our broad analysis demonstrates that the qBiomarker's performance is on par with that of other labour-intensive and expensive methods of cancer mutation detection of frequently altered cancer-associated genes, and provides a foundation for supporting its consideration as an option for molecular diagnostics. CONCLUSIONS: This large-scale direct comparison and validation of currently available mutation detection approaches is extremely relevant for the current scenario of precision medicine and will lead to informed choice of screening methodologies, especially in lower budget conditions or time frame limitations.

Antiretroviral Therapy in Simian Immunodeficiency Virus-Infected Sooty Mangabeys: Implications for AIDS Pathogenesis.

UNLABELLED: Simian immunodeficiency virus (SIV)-infected sooty mangabeys (SMs) do not develop AIDS despite high levels of viremia. Key factors involved in the benign course of SIV infection in SMs are the absence of chronic immune activation and low levels of infection of CD4(+) central memory (TCM) and stem cell memory (TSCM) T cells. To better understand the role of virus replication in determining the main features of SIV infection in SMs, we treated 12 SMs with a potent antiretroviral therapy (ART) regimen for 2 to 12 months. We observed that ART suppressed viremia to <60 copies/ml of plasma in 10 of 12 animals and induced a variable decrease in the level of cell-associated SIV DNA in peripheral blood (average changes of 0.9-, 1.1-, 1.5-, and 3.7-fold for CD4(+) transitional memory [TTM], TCM, effector memory [TEM], and TSCM cells, respectively). ART-treated SIV-infected SMs showed (i) increased percentages of circulating CD4(+) TCM cells, (ii) increased levels of CD4(+) T cells in the rectal mucosa, and (iii) significant declines in the frequencies of HLA-DR(+) CD8(+) T cells in the blood and rectal mucosa. In addition, we observed that ART interruption resulted in rapid viral rebound in all SIV-infected SMs, indicating that the virus reservoir persists for at least a year under ART despite lower infection levels of CD4(+) TCM and TSCM cells than those seen in pathogenic SIV infections of macaques. Overall, these data indicate that ART induces specific immunological changes in SIV-infected SMs, thus suggesting that virus replication affects immune function even in the context of this clinically benign infection. IMPORTANCE: Studies of natural, nonpathogenic simian immunodeficiency virus (SIV) infection of African monkeys have provided important insights into the mechanisms responsible for the progression to AIDS during pathogenic human immunodeficiency virus (HIV) infection of humans and SIV infection of Asian macaques. In this study, for the first time, we treated SIV-infected sooty mangabeys, a natural host for the infection, with a potent antiretroviral therapy (ART) regimen for periods ranging from 2 to 12 months and monitored in detail how suppression of virus replication affected the main virological and immunological features of this nonpathogenic infection. The observed findings provide novel information on both the pathogenesis of residual immunological disease under ART during pathogenic infection and the mechanisms involved in virus persistence during primate lentiviral infections.

Estrogens as a Possible Therapeutic Strategy for the Management of Neuroinflammation and Neuroprotection in COVID-19.

The Coronavirus disease 2019 (COVID-19) affects several tissues, including the central and peripheral nervous system. It has also been related to signs and symptoms that suggest neuroinflammation with possible effects in the short, medium, and long term. Estrogens could have a positive impact on the management of the disease, not only due to its already known immunomodulator effect, but also activating other pathways that may be important in the pathophysiology of COVID-19, such as the regulation of the virus receptor and its metabolites. In addition, they can have a positive effect on neuroinflammation secondary to pathologies other than COVID-19. The aim of this study is to analyze the molecular mechanisms that link estrogens with their possible therapeutic effect for neuroinflammation related to COVID-19. Advanced searches were performed in scientific databases as Pub- Med, ProQuest, EBSCO, the Science Citation index, and clinical trials. Estrogens have been shown to participate in the immune modulation of the response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition to this mechanism, we propose that estrogens can regulate the expression and activity of the Angiotensin-converting enzyme 2 (ACE2), reestablishing its cytoprotective function, which may be limited by its interaction with SARS-CoV-2. In this proposal, estrogens and estrogenic compounds could increase the synthesis of Angiotensin-(1-7) (Ang-(1-7)) that acts through the Mas receptor (MasR) in cells that are being attacked by the virus. Estrogens can be a promising, accessible, and low-cost treatment for neuroprotection and neuroinflammation in patients with COVID-19, due to its direct immunomodulatory capacity in decreasing cytokine storm and increasing cytoprotective capacity of the axis ACE2/Ang (1-7)/MasR.

Correction: Long, S. SARS-CoV-2 Subgenomic RNAs: Characterization, Utility, and Perspectives. Viruses 2020, 13, 1923.

The author is no longer affiliated with the original institution "AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA", so the author wishes to change the affiliation to "Independent Researcher, Clarksburg, MD 20871, USA" [...].

The emerging role of ultrasound in detecting interstitial lung disease in patients with rheumatoid arthritis.

OBJECTIVE: To investigate the potential role of US in the detection of ILD in a cohort of patients with RA. METHODS: Patients with diagnosis of RA were consecutively enrolled. All patients underwent pulmonary examination, laboratory data, DLCO measure, chest HRCT and radiographs, and US examination. A healthy group was included as control group. US was performed according the 14-intercostal space scanning protocol using the following semiquantitative scale [0=normal (≤5 B-lines); 1=slight (≥6 and ≤15 B-lines); 2=moderate, (≤16 and ≥30 B-lines); 3=severe (≥30 B-lines)]. RESULTS: A total of 74 RA patients and 74 healthy controls were included. Thirty of 74 patients (40.5%) showed US signs of ILD with respect to the healthy controls (3 subjects, 4.1%) (P<0.001); whereas HRCT showed ILD in 27 (36.4%) of 74 patients. Among the 30 patients that showed US findings of ILD, 17 (56.6%) were asymptomatic from respiratory view-point. The sensitivity and specificity of US were 92% and 89% respectively. A positive correlation between US and HRCT findings were found (P<0.001) whereas no correlation was found with chest radiographs and DLCO findings. Positive association between US findings and DAS28-ESR, anti-CCP and RF (P<0.01 for each respectively) was found. Feasibility, represented by the mean time spent to perform the pulmonary US assessment was 7.8minutes (±SD 1.2, range 6 to 10minutes). CONCLUSIONS: Our results support the potential of US in detect accurately ILD in patients with RA and provide a rationale to consider it as a friendly screening tool to be implemented in early phases of the disease.

Potential Neuroprotective Effect of Cannabinoids in COVID-19 Patients.

The global pandemic caused by the SARS-CoV-2 virus began in early 2020 and is still present. The respiratory symptoms caused by COVID-19 are well established. However, neurological manifestations that may result from direct or indirect neurological damage after SARS-CoV-2 infection have been reported frequently. The main proposed pathophysiological processes leading to neurological damage in COVID-19 are cerebrovascular disease and indirect inflammatory/ autoimmune origin mechanisms. A growing number of studies confirm that neuroprotective measures should be maintained in COVID-19 patients. On the other hand, cannabinoids have been the subject of various studies that propose them as potentially promising drugs in chronic neurodegenerative diseases due to their powerful neuroprotective potential. In this review, we addresses the possible mechanism of action of cannabinoids as a neuroprotective treatment in patients infected by SARS-CoV-2. The endocannabinoid system is found in multiple systems within the body, including the immune system. Its activation can lead to beneficial results, such as a decrease in viral entry, a reduction of viral replication, and a reduction of pro-inflammatory cytokines such as IL-2, IL-4, IL-6, IL-12, TNF-α, or IFN-c through CB2R expression induced during inflammation by SARS-CoV-2 infection in the central nervous system.

Neuropathic Pain in Parkinson's Disease.

Pain is a well-recognized and important non-motor manifestation in Parkinson disease (PD). Painful or unpleasant sensations in PD can be classified as musculoskeletal, dystonia, akathisia, radicular, and central or primary pain; the last two are associated with neuropathic pain. Particularly, neuropathic pain in PD has not been fully clarified; therefore, it goes somewhat unnoticed, and the affected patients do not receive adequate pain treatment. The main purpose of this literature review was to identify the incidence of neuropathic pain in PD and the involvement of dopamine of this type of pain by the integration of different lines of investigation. In this review, a search was conducted using PubMed, ProQuest, EBSCO, Medline, EMBASE, and the Science Citation index for studies evaluating pain in patients with PD. The inclusion criteria were as follows: original articles that evaluated incidence and possible mechanism of neuropathic, central, and radicular pain in PD. Nine studies related to the incidence of neuropathic pain in PD suggest the activation of cerebral areas, such as the cortex, striatum, amygdala, thalamus, raphe nuclei, and locus coeruleus. Neuropathic pain is related to altered levels of dopamine, serotonin, and norepinephrine; these neurotransmitters are related to the sensitive and emotional dimensions of pain. Dopamine could cause hypersensitivity to pain, either indirectly through modulatory effects on affective pain processing and/or directly by affecting the neural activity in key areas of the brain that modulate pain. A considerable proportion of patients with PD suffer neuropathic pain; however, it has been disregarded, this has led to an inability to achieve an adequate treatment and a decrease in pain to improve the quality of life of these patients. We consider that neuropathic pain in PD is possibly induced by neurophysiological changes due to the degradation of dopaminergic neurons.

Trends in Gliosis in Obesity, and the Role of Antioxidants as a Therapeutic Alternative.

Obesity remains a global health problem. Chronic low-grade inflammation in this pathology has been related to comorbidities such as cognitive alterations that, in the long term, can lead to neurodegenerative diseases. Neuroinflammation or gliosis in patients with obesity and type 2 diabetes mellitus has been related to the effect of adipokines, high lipid levels and glucose, which increase the production of free radicals. Cerebral gliosis can be a risk factor for developing neurodegenerative diseases, and antioxidants could be an alternative for the prevention and treatment of neural comorbidities in obese patients. AIM: Identify the immunological and oxidative stress mechanisms that produce gliosis in patients with obesity and propose antioxidants as an alternative to reducing neuroinflammation. METHOD: Advanced searches were performed in scientific databases: PubMed, ProQuest, EBSCO, and the Science Citation index for research on the physiopathology of gliosis in obese patients and for the possible role of antioxidants in its management. CONCLUSION: Patients with obesity can develop neuroinflammation, conditioned by various adipokines, excess lipids and glucose, which results in an increase in free radicals that must be neutralized with antioxidants to reduce gliosis and the risk of long-term neurodegeneration.

SARS-CoV-2 Subgenomic RNAs: Characterization, Utility, and Perspectives.

SARS-CoV-2, the etiologic agent at the root of the ongoing COVID-19 pandemic, harbors a large RNA genome from which a tiered ensemble of subgenomic RNAs (sgRNAs) is generated. Comprehensive definition and investigation of these RNA products are important for understanding SARS-CoV-2 pathogenesis. This review summarizes the recent progress on SARS-CoV-2 sgRNA identification, characterization, and application as a viral replication marker. The significance of these findings and potential future research areas of interest are discussed.

Putative mechanism of neurological damage in COVID-19 infection.

The recent pandemic of the coronavirus infectious disease 2019 (COVID-19) has affected around 192 countries, and projections have shown that around 40% to 70% of world population could be infected in the next months. COVID-19 is caused by the virus SARS- CoV-2, it enters the cells through the ACE2 receptor (angiotensin converting enzyme 2). It is well known that SARS-CoV-2 could develop mild, moderate, and severe respiratory symptoms that could lead to death. The virus receptor is expressed in different organs such as the lungs, kidney, intestine, and brain, among others. In the lung could cause pneumonia and severe acute respiratory syndrome (SARS). The brain can be directly affected by cellular damage due to viral invasion, which can lead to an inflammatory response, by the decrease in the enzymatic activity of ACE2 that regulates neuroprotective, neuro-immunomodulatory and neutralizing functions of oxidative stress. Another severe damage is hypoxemia in patients that do not receive adequate respiratory support. The neurological symptoms that the patient presents, will depend on factors that condition the expression of ACE2 in the brain such as age and sex, as well as the mechanism of neuronal invasion, the immune response and the general state of the patient. Clinical and histopathological studies have described neurological alterations in human patients with COVID-19. These conditions could have a possible contribution to the morbidity and mortality caused by this disease and may even represent the onset of neurodegenerative activity in recovered patients.The recent pandemic of the coronavirus infectious disease 2019 (COVID-19) has affected around 192 countries, and projections have shown that around 40% to 70% of world population could be infected in the next months. COVID-19 is caused by the virus SARS- CoV-2, it enters the cells through the ACE2 receptor (angiotensin converting enzyme 2). It is well known that SARS-CoV-2 could develop mild, moderate, and severe respiratory symptoms that could lead to death. The virus receptor is expressed in different organs such as the lungs, kidney, intestine, and brain, among others. In the lung could cause pneumonia and severe acute respiratory syndrome (SARS). The brain can be directly affected by cellular damage due to viral invasion, which can lead to an inflammatory response, by the decrease in the enzymatic activity of ACE2 that regulates neuroprotective, neuro-immunomodulatory and neutralizing functions of oxidative stress. Another severe damage is hypoxemia in patients that do not receive adequate respiratory support. The neurological symptoms that the patient presents, will depend on factors that condition the expression of ACE2 in the brain such as age and sex, as well as the mechanism of neuronal invasion, the immune response and the general state of the patient. Clinical and histopathological studies have described neurological alterations in human patients with COVID-19. These conditions could have a possible contribution to the morbidity and mortality caused by this disease and may even represent the onset of neurodegenerative activity in recovered patients.