Diagnosis and Management of Hepatitis C Virus Infection

Point-of-Care Testing for Infectious Diseases Based on Class 2 CRISPR/Cas Technology

The early detection of infectious diseases and microorganisms is critical for effective disease treatment, control, and prevention. Currently, nucleic acid testing and antigen-antibody serum reaction are the two methods most commonly used for the detection of infectious diseases. The former is highly accurate, specific, and sensitive, but it is time-consuming, expensive, and has special technician and instrument requirements. The latter is rapid and economical, but it may not be accurate and sensitive enough. Therefore, it is necessary to develop a quick and on-site diagnostic test for point-of-care testing (POCT) to enable the clinical detection of infectious diseases that is accurate, sensitive, convenient, cheap, and portable. Here, CRISPR/Cas-based detection methods are detailed and discussed in depth. The powerful capacity of these methods will facilitate the development of diagnostic tools for POCT, though they still have some limitations. This review explores and highlights POCT based on the class 2 CRISPR/Cas assay, such as Cas12 and Cas13 proteins, for the detection of infectious diseases. We also provide an outlook on perspectives, multi-application scenarios, clinical applications, and limitations for POCT based on class 2 CRISPR/Cas technology.

Aspects of cognitive assessments and spectroscopic magnetic resonance imaging in people with chronic hepatitis C: a systematic review

Extrahepatic manifestations are common in people with hepatitis C virus (HCV). Cognitive changes are pointed out, but the mechanisms are still uncertain. The aim of this systematic review was to analyze studies involving spectroscopic magnetic resonance in people infected with HCV, which also included cognitive tests. The research occurred in six databases (Directory of Open Access Journals, Lilacs, Medcaribe, Medline, Scielo and ScienceDirect) and the selection of studies was carried out in two stages: search for titles and abstracts, then reading of the full articles, excluding those that did not meet the eligibility criteria. 12,888 titles and abstracts were selected, but only 6 articles were included in the review. Impairments in attention, concentration, speed of information processing, memory, verbal fluency and executive functions were identified as well as an increase in the Cho/Cr and mI/Cr ratios and a reduction in the NAA/Cr ratio in some included studies. Longitudinal studies, with more homogeneous samples and methods, as well as with better controlled confounding factors, are necessary to adequately identify the effect of HCV on the brain.

An Insight into Hepatitis C Virus: In Search of Promising Drug Targets

Hepatitis C Virus (HCV) is a global health concern, chronically infecting over 70 million people worldwide. HCV is a bloodborne pathogen that primarily affects the liver, and chronic HCV infection can lead to cirrhosis, liver cancer, and liver failure over time. There is an urgent need for more effective approaches to prevent and treat HCV. This review summarizes current knowledge on the virology, transmission, diagnosis, and management of HCV infection. It also provides an in-depth analysis of HCV proteins as promising targets for antiviral drug and vaccine development. Specific HCV proteins discussed as potential drug targets include the NS5B polymerase, NS3/4A protease, entry receptors like CD81, and core proteins. The implications of HCV proteins as diagnostic and prognostic biomarkers are also explored. Current direct-acting antiviral therapies are effective but have cost, genotype specificity, and resistance limitations. This review aims to synthesize essential information on HCV biology and pathogenesis to inform future research on improved preventive, diagnostic, and therapeutic strategies against this global infectious disease threat.

Progress, evolving therapeutic/diagnostic approaches, and challenges in the management of hepatitis C virus infections

Hepatitis C virus (HCV) infections are emerging as one of the foremost challenges in healthcare owing to its chronicity and the virus’s quasispecies nature. Worldwide, over 170 million people are chronically infected with HCV, with an annual mortality of over 500,000 people across the world. The emerging pathophysiological evidence links HCV infections to a risk of developing liver diseases such as cirrhosis and hepatocellular carcinoma. Despite the great strides that have been made towards understanding the pathophysiology of disease progression, the tailored treatments of HCV infection remain to be established. The present review provides an update of the literature pertaining to evolving therapeutic approaches and prophylactic measures for the effective management of HCV infections. An extensive discussion of established and experimental immune prophylactic measures also sheds light on current developments in the design of vaccination strategies against HCV infection. We have also attempted to address the application of nanotechnology in formulating effective therapeutic interventions against HCV. Pointing out the limitations of the existing diagnostic methods and therapeutic approaches against HCV might inspire the design and development of novel, efficient, reliable, and cost-effective diagnostic technologies as well as novel therapeutic and immune prophylactic interventions for the effective management of HCV.

Regenerative Medicine of Liver: Promises, Advances and Challenges

Liver tissue engineering is a rapidly developing field which combines the novel use of liver cells, appropriate biochemical factors, and engineering principles, in order to replace or regenerate damaged liver tissue or the organ. The aim of this review paper is to critically investigate different possible methods to tackle issues related with liver diseases/disorders mainly using regenerative medicine. In this work the various regenerative treatment options are discussed, for improving the prognosis of chronic liver disorders. By reviewing existing literature, it is apparent that the current popular treatment option is liver transplantation, although the breakthroughs of stem cell-based therapy and bioartificial liver technology make them a promising alternative.

Undergraduate Medical School Health Fair Hepatitis Screenings: Utilizing Non-Profit Community Organizations

Background:

Undergraduate medical schools serve a critical role in providing screenings to medically underserved populations through the use of health fairs. Non-profit community organizations (NPCO) often participate by providing local credibility, administrative resources, and technical knowledge. Here we present a three-year narrative of hepatitis B and C screening efforts to highlight the challenges and benefits of undergraduate medical school and NPCO partnerships.

Methods:

Hepatitis screenings were conducted at biannual health fairs in Harlem, New York from 2017 to 2019. Meeting minutes from post-event debriefings were analyzed to identify any overarching themes with NPCOs.

Results:

NPCOs share a common goal in working with the community to advance their access to medical care and treatment. Communication and prompt follow-up are critical to maintaining expectations between NPCOs and health fair organizers.

Conclusions:

NPCOs can play an important role in encouraging, outreaching, and even managing hepatitis screening initiatives in conjunction with medical school health fairs.

Hepatitis C virus (HCV) diagnosis via microfluidics

Humans are subjected to various diseases; hence, proper diagnosis helps avoid further disease consequences. One such severe issue that could cause significant damage to the human liver is the hepatitis C virus (HCV). Several techniques are available to detect HCV under various categories, such as detection through antibodies, antigens, and RNA. Although immunoassays play a significant role in discovering hepatitis viruses, there is a need for point-of-care tests (POCT). Some developing strategies are required to ensure the appropriate selection of POCT for HCV detection, initiate appropriate antiviral therapy, and define associated risks, which will be critical in achieving optimal outcomes. Though molecular assays are precise, reproducible, sensitive, and specific, alternative strategies are required to enhance HCV diagnosis among the infected population. Herein, we described and assessed the potential of various microfluidic detection techniques and confirmatory approaches used in present communities. In addition, current key market players in HCV chip-based diagnosis and the future perspectives on the basis of which the diagnosis can be made easier are presented in the present review.

Fully automated rapid quantification of Hepatitis C Virus RNA in human plasma and serum by integrated on-chip RT-qPCR and capillary electrophoresis

The quantification of hepatitis C virus (HCV) is essential for the management of chronic hepatitis C therapy. We have developed a fully automated microfluidic RT-qPCR system for rapid quantitative detection of HCV RNA in human EDTA-plasma and serum, and the performance of the method was assessed. The platform for the assay, µTASWako g1 Fully Automated Genetic Analyzer, performs automated sample preparation and RNA extraction, followed by amplification and detection on an integrated RT-qPCR-CE (capillary electrophoresis (CE)) microfluidic chip. The total assay time from sample input to data output is less than 120 minutes. The HCV assay has a linear quantitative range of 15 to 10⁷ IU/mL, with a limit of detection (LOD) of 10.65 IU/mL in EDTA-plasma and 12.43 IU/mL in serum. The assay has a reproducibility of SD ≤ 0.16 log₁₀ IU/mL and an accuracy of ≤ 0.22 log₁₀ IU/mL difference when compared to the assigned values. The main HCV genotypes 1 to 6 are detected with an accuracy of ± 0.3 log₁₀ IU/mL. The assay is specific for HCV RNA and is free of interference from non-HCV pathogens, elevated levels of anti-viral and anti-bacterial drugs, and common endogenous interferents. In the linear quantitative range, the assay is highly correlated with the Roche cobas AmpliPrep/cobas TaqMan HCV Test, version 2.0 (r² = 0.949). As the assay is highly sensitive, accurate and specific, and provides reliable quantification of HCV in plasma and serum, it can potentially be applicable for monitoring the therapy and management of HCV infection.

Harmonization of Zika neutralization assays by using the WHO International Standard for anti-Zika virus antibody

During outbreaks of emerging viruses, such as the Zika outbreak in 2015-2016, speed and accuracy in detection of infection are critical factors to control the spread of the disease; often serological and diagnostic methods for emerging viruses are not well developed and validated. Thus, vaccines and treatments are difficult to evaluate due to the lack of comparable methods. In this study, we show how the 1st WHO International Standard for anti-Zika antibody was able to harmonize the neutralization titres of a panel of serological Zika-positive samples from laboratories worldwide. Expression of the titres in International Unit per millilitre reduced the inter-laboratory variance, allowing for greater comparability between laboratories. We advocate the use of the International Standard for anti-Zika virus antibodies for the calibration of neutralization assays to create a common language, which will permit a clear evaluation of the results of different clinical trials and expedite the vaccine/treatment development.

Prediction of HCV load using genotype, liver biomarkers, and clinical symptoms by a mathematical model in patients with HCV infection

Hepatitis C virus (HCV) infection is a major public health problem with about 1.75 million new HCV cases and 71 million chronic HCV infections worldwide. The study aimed to evaluate clinical, serological, molecular, and liver markers to develop a mathematical predictive model for the quantification of the HCV viral load in chronic HCV infected patients. In this cross-sectional study, blood samples were taken from 249 recently diagnosed HCV-infected subjects and were tested for liver condition, viral genotype, and HCV RNA load. Receiver operating characteristics (ROC) curves and multiple linear regression analysis were used to predict the HCV-RNA load. Genotype 3 followed by genotype 1 were the most prevalent genotypes in Mashhad, Northeastern Iran. The maximum levels of viral load were detected in the mixed genotype group, and the lowest levels in the undetectable genotype group. The log of the HCV viral load was significantly associated with thrombocytopenia and higher serum levels of alanine transaminase (ALT). In addition, the log HCV RNA was significantly higher in patients with arthralgia, fatigue, fever, vomiting, or dizziness. Moreover, genotype 3 was significantly associated with icterus. A ROC curve analysis revealed that the best cut-off points for serum levels of aspartate aminotransferase (AST), ALT, and alkaline phosphatase (ALP) were >31, >34, and ≤246 IU/L, respectively. Sensitivity, specificity, and positive predictive values for AST were 87.7%, 84.36%, and 44.6%, for ALT they were 83.51%, 81.11%, and 36%, and for ALP were 72.06%, 42.81%, and 8.3%, respectively. A mathematical regression model was developed that could estimate the HCV-RNA load. Regression model: log viral load = 7.69 - 1.01 × G3 - 0.7 × G1 + 0.002 × ALT - 0.86 × fatigue.

Effect of sofosbuvir and daclatasvir on lipid profile, glycemic control and quality of life index in chronic hepatitis C, genotype 3 patients

OBJECTIVES

The management of hepatitis C has progressed from interferon-based therapy to oral direct acting antiviral therapy. Deranged lipid levels (total cholesterol, triglyceride) after treatment with interferon-based therapy are well known. There is a paucity of data on changes in lipid profile, glycemic parameters and alteration in quality of life with the newer regimen. This study was designed to assess the changes in lipid profile, glycemic parameters, quality of life in chronic hepatitis C patients with genotype 3 after treatment with sofosbuvir and daclatasvir.

METHODS

The study was a single-centre, prospective study, conducted at tertiary care hospital from January 2017 to December 2017. Fifty patients, who received sofosbuvir (400 mg) and daclatasvir (60 mg) orally once daily for a period of 12 weeks for chronic hepatitis C and genotype 3, were recruited.

RESULTS

Total cholesterol levels (166.9 ± 23.8 to 192.4 ± 34.5 mg/dL, p-value < 0.0001) and low-density cholesterol (LDL) levels (100.9 ± 22.8 to 121.6 ± 37.2, p-value < 0.0001) were elevated after the treatment. A significant decrease in median levels of glycated hemoglobin (HbA1c) was observed (5.57% to 5.41%, p-value < 0.002). Quality of life markedly improved in all domains, i.e. physical, physiological, environmental, and social relationships according to an abbreviated form of World Health Organization quality of life assessment named WHOQOL-BREF questionnaire. Treatment was found to be effective with sustained virological response (SVR) achieved in 94% patients.

CONCLUSIONS

Our study reports a substantial increment in total cholesterol, and low-density lipoprotein with sofosbuvir and daclatasvir treatment though it achieved SVR in 94% of patients and improved their quality of life.

Potential pathogenic mechanisms involved in the association between lichen planus and hepatitis C virus infection

Lichen planus (LP) is an immune-mediated inflammatory disease that particularly affects the skin and mucous membranes. Its etiology remains elusive, however some trigger factors, including viral or bacterial antigens, drugs and metals, have been postulated. There is a higher prevalence of hepatitis C virus (HCV) infection among patients with LP, with some geographical variations. HCV is an enveloped RNA virus that belongs to the Flaviviridae family and in most instances causes chronic liver infections. It has been hypothesized that HCV may contribute to LP development, but the link between the two disorders is not fully understood. It is still debatable whether HCV leads to the occurrence of LP lesions directly by replication inside the infected cells or indirectly by activating immunological pathways. Molecular studies have revealed HCV RNA in specimens collected from patients with LP. The autoimmune theory was also suggested given that several studies have revealed viral replication and immune response activation associated with autoantibody synthesis. The aim of this review is to summarize the main potential mechanisms involved in the association between LP and HCV infection. Understanding the link between the two disorders may shed some light on the pathogenesis of LP, which is a challenging issue.

Prevalence and risk factors of Occult Hepatitis C infections in blood donors from Mexico City

Background

The circulatory system is the main mechanism for transmission of the Hepatitis C Virus (HCV). A new class of HCV infections, Occult HCV infection (OCI), is defined as the presence of HCV-RNA in hepatocytes with the absence of HCV in the serum/plasma utilizing current laboratory assays. Different groups have reported the prevalence of OCI; however, its associated risk factors have not been established. In Mexico, there are no reports about OCI, so the objective of our study was to determine the prevalence of OCI in total blood donors in Mexico City, as well as its associated risk factors.

Methods

Blood donors that were considered eligible for donation, according to NOM 253-SSA1-2012, were randomly selected. Demographic data was collected from 1,037 donors. Plasma and peripheral blood mononuclear cells were assessed for HCV-RNA. The presence of HCV-RNA was determined by nested PCR for the 5'-UTR region. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (95%CI) to determine the level of association.

Results

The prevalence of OCI was 3.4% among blood donors. Homosexual relationships (OR = 5.52, 95%CI: 1.53–19.92, p<0.05) and acupuncture (OR = 3.56, 95%CI: 1.41–8.98, p<0.05) were significantly associated with OCI.

Conclusion

There is a significant presence of OCI in the blood donor population in Mexico City. The main risk factors for OCI transmission are homosexual relationships and acupuncture. This study supports the increased use of sensitive and specific screening tests for blood bank testing.

Detection of Hepatitis C Virus RNA in Blood and Saliva of Transfusion-Dependent Thalassemia Patients Diagnosed with Hepatitis C

Background:

The aim of the current study was to detect hepatitis C virus (HCV) RNA in blood and saliva of a population of patients with thalassemia who have HCV antibody in their serum.

Materials and Methods:

In this cross-sectional study, blood and saliva samples were collected and were analyzed with quantitative reverse transcription polymerase chain reaction (RT-PCR) for the detection of HCV RNA. In addition, liver-related blood tests were performed, and patients’ medical history was recorded. Data were analyzed by independent samples t-test and Chi-square with a significant level of 0.05.

Results:

Overall, 62 adult patients (29 males and 33 females) were included. Most (87%) of the patients had major thalassemia and genotype 1a was the most common (42%) type. HCV RNA was detected in 71 and 16% of blood and saliva samples, respectively. HCV RNA was detected more in female patients (31%) (P = 0.003) and in intermediate thalassemia (50%) (P < 0.005). The mean age of the patients with positive saliva was almost 10 years older (P < 0.001), and the mean number of blood transfusion was fewer in positive saliva group (P = 0.037). The sensitivity, specificity, and positive and negative predictive values of saliva PCR was calculated to be 18%, 88%, 80%, and 69%, respectively.

Conclusion:

Saliva contained HCV RNA in 16% of the assessed population. The probability of detection of HCV RNA in saliva increased in older patients, less number of blood transfusions, females and intermediate thalassemia. Saliva RT-PCR demonstrated low sensitivity and high specificity with high positive predictive value in the assessed population.

Global Mortality Burden of Cirrhosis and Liver Cancer Attributable to Injection Drug Use, 1990-2016: An Age-Period-Cohort and Spatial Autocorrelation Analysis

We analyzed the temporal and spatial variations in mortality burden of cirrhosis and liver cancer attributable to injection drug use (IDU) from 1990 to 2016. Mortality data of IDU-attributable cirrhosis and IDU-attributable liver cancer on the global and national scales from 1990 to 2016 were collected from the Global Burden of Disease (GBD) studies. Age-period-cohort (APC) model analysis was used to analyze the global mortality trends of target disease, and spatial autocorrelation analysis based on Geographic Information System was applied to illustrate the clusters of the most epidemic countries. Globally, from 1990 to 2015, mortality rates (age-standardized, per 100,000) of IDU-attributable cirrhosis increased continually from 1.5 to 1.9, while from 0.4 to 0.9 for IDU-attributable liver cancer. The APC model analysis indicated that the increases of mortality were mainly driven by period effects, with the mortality risk increasing by 6.82-fold for IDU-attributable cirrhosis and 3.08-fold for IDU-attributable liver cancer. The spatial analysis suggested that IDU-attributable cirrhosis mortality were geographically clustered from 1990 to 2016, and hot spots were mainly located in less well developed countries of Latin America, East and Central Europe and Central Asia. Our study provides epidemiological evidence for global interventions against advanced liver disease among injection drug users (IDUs).

Immiscible phase filter extraction and equivalent amplification of genotypes 1-6 of hepatitis C RNA: The building blocks for point-of-care diagnosis

The lack of hepatitis C virus (HCV) diagnostic tests designed for use in decentralized settings is a major obstacle for providing access to treatment and prevention services particularly in low and middle income countries. Here we describe the development and validation of two building blocks of the HCV Quant Assay, a test in development for point-of-care use: 1) an RT-qPCR assay with noncompetitive internal control that equivalently detects the 6 major HCV genotypes and 2) an automated sample prep method using immiscible phase filter technology. This novel assay has wide dynamic range of HCV quantification and a limit of detection of 30IU/ml with 200μl specimen volume. In a preliminary study of 61 clinical specimens, the HCV Quant Assay demonstrated 100% sensitivity and specificity and gave comparable viral load results across 4 logs of IU/ml when compared to the Abbott RealTime HCV Assay.

Impact of liver disease on outcomes of patients hospitalized for epistaxis

OBJECTIVES

Liver disease (LD) often results in coagulation abnormalities that may predispose to more severe epistaxis. The purpose of this analysis was to examine characteristics of patients hospitalized for epistaxis with LD and explore the impact of LD on patient outcomes.

METHODS

The 2002 to 2013 National Inpatient Sample was queried for cases with a primary diagnosis of epistaxis. Cases with additional codes meeting the Agency for Healthcare Research and Quality's definition of LD were identified and compared to the non-LD cohort.

RESULTS

Out of 39,879 cases meeting inclusion criteria, 3.6% had LD. LD was associated with younger age (55.7 years vs. 67.5 years; P < 0.001), longer hospital stay (3.9 days vs. 3.2 days; P < 0.001), and greater hospital charges ($26,141 vs. $18,200; P < 0.001) compared to the non-LD cohort. LD patients had higher rates of alcohol abuse, coagulopathy, chronic blood loss anemia, and renal failure. LD patients also had higher rates of sepsis, urinary/renal complications, respiratory failure, and infectious pneumonia. LD was associated with decreased rates of aggressive management (defined as ligation or embolization) (6.6%-9.0%; P < 0.002) and anterior or posterior nasal packing. In our multivariate logistic regression model correcting for age, gender, race, and significant comorbidities, LD was associated with 1.520 (1.336-1.729; P < 0.001) greater odds of transfusion and 2.264 (1.372-3.736; P = 0.001) greater odds of in-hospital mortality.

CONCLUSION

Among patients hospitalized for epistaxis, LD resulted in greater morbidity and mortality. Clinicians should be aware of the particular risk that LD bears on the hospitalized epistaxis patient.

LEVEL OF EVIDENCE

2C. Laryngoscope, 127:2691-2697, 2017.

IFNL4 polymorphism as a predictor of chronic hepatitis C treatment efficiency in Ukrainian patients

The aim of this study was to examine association between IFNL4 gene ss469415590 and treatment efficiency in group of Ukrainian PEG-interferon/ribavirin-treated chronic hepatitis C patients. Study group consisted of 92 unrelated hepatitis C virus genotype 1 mono-infected patients: case group-29 patients with late or absent virological response; control group-63 patients with sustained virological response. Study material was genomic DNA. Genotyping was performed using amplification-refractory mutation system PCR. Statistical analysis was performed using GenePop and OpenEpi statistical packages. Obtained results show that ss469415590 ΔG/ΔG genotype is associated with poor virological response (OR = 3.62; CI 95%: 1.12-11.67) in PEG-interferon/ribavirin-treated chronic hepatitis C patients from Ukraine.

A novel real-time reverse transcription-polymerase chain reaction assay with partially double-stranded linear DNA probe for sensitive detection of hepatitis C viral RNA

The detection and quantification of HCV RNA is very helpful for the management and treatment of HCV related diseases. Detection of low HCV viral load is a great challenge in HCV RNA detection. Here, we developed a novel real-time RT-PCR assay with partially double-stranded linear DNA probe which can detect all HCV genotypes and improve the detection performance. The novel assay has a wide linear dynamic range of HCV RNA quantification (1×10(2)-1×10(11)IU/ml) and a limit of detection of 78IU/ml. The assay exhibits an excellent reproducibility with 2.52% and 1.33% coefficients of variations, for inter- and intra-assays, respectively. To evaluate the viability of the assay, a comparison with a commercial HCV RNA detection kit was performed using 106 serum samples. The lineared correlation coefficient between the novel assay and the commercial HCV RNA detection kit was 0.940. Meanwhile, the deviation between the two methods was tolerable. Therefore, the novel real-time RT-PCR assay was applicable for laboratory diagnosis and monitoring of HCV infection.

High-resolution melting combines with Bayes discriminant analysis: a novel hepatitis C virus genotyping method

Current hepatitis C virus (HCV) genotyping techniques are often highly technical, costly, or need improvements in sensitivity and specificity. These limitations indicate the need of novel methods for HCV genotyping. The present study aimed to develop a novel genotyping method combining high-resolution melting (HRM) analysis with Bayes discriminant analysis (BDA). Target gene fragment including 5'-untranslated and core region was selected. Four or five inner amplicons for every serum were amplified using nested PCR, HRM was used to determine the melting temperature of the amplicons, and HCV genotypes were then analyzed utilizing BDA. In initial genotyping (HCV genotypes were classified into 1b, 2a, 3a, 3b, and 6a), both the overall accuracy rate and the cross-validation accuracy rate were 92.6 %, external validation accuracy rate was 95.0 %. To enhance the accuracy rate of genotyping, HCV genotypes were firstly classified into 1b, 3a, 3b, and 2a-6a, followed by a supplementary genotyping for 2a-6a. Both the overall accuracy rate and the cross-validation accuracy rate reached 97.5 %, and external validation accuracy rate was 100 %. Comparing adjusted HRM genotyping with type-specific probe technique, the difference in accuracy rates was not significant. However, the limit of detection and cost were lower for HRM. Comparing with sequencing, the limit detection of HRM was the same as the former, but the cost of HRM was lower. Hence, HRM combined with BDA was a novel method that equipped with superior accuracy, high sensitivity, and lower cost and therefore could be a better technique for HCV genotyping.

MicroRNAs Expressed during Viral Infection: Biomarker Potential and Therapeutic Considerations

MicroRNAs (miRNAs) are short sequences of noncoding single-stranded RNAs that exhibit inhibitory effects on complementary target mRNAs. Recently, it has been discovered that certain viruses express their own miRNAs, while other viruses activate the transcription of cellular miRNAs for their own benefit. This review summarizes the viral and/or cellular miRNAs that are transcribed during infection, with a focus on the biomarker and therapeutic potential of miRNAs (or their antagomirs). Several human viruses of clinical importance are discussed, namely, herpesviruses, polyomaviruses, hepatitis B virus, hepatitis C virus, human papillomavirus, and human immunodeficiency virus.