BackgroundTorque Teno Virus (TTV) is a DNA virus with high rate of prevalence globally. Since its discovery in 1997, several studies have questioned the role of this virus in causing disease. However, it still remains an enigma. Although methods are available for detection of TTV infection, there is still a need for simple, rapid and reliable method for screening of this virus in human population. Present investigation describes the cloning and expression of N22 region of TTV-genome and the use of expressed peptide in development of immunoassay to detect anti-TTV antibodies in serum. Since TTV genotype-1 is more common in India, the serum positive for genotype-1 was used as source of N22 for expression purpose.MethodsFull length N22 region of ORF1 from TTV genotype-1 was amplified and cloned in pGEM®-T Easy vector. After cloning, the amplicon was transformed and expressed as a fusion protein containing hexa-histidine tag in pET-28a(+) vector using BL21 E. coli cells as host. Expression was conducted both in LB medium as well as ZYP-5052 auto-induction medium. The expressed peptide was purified using metal-chelate affinity chromatography and used as antigen in developing a blot immunoassay.ResultsAnalysis of translated product by SDS-PAGE and western blotting demonstrated the presence of 25 kDa polypeptide produced after expression. Solubility studies showed the polypeptide to be associated with insoluble fraction. The use of this peptide as antigen in blot assay produced prominent spot on membrane treated with sera from TTV-infected patients. Analysis of sera from 75 patients with liver and renal diseases demonstrated a successful implication of N22 polypeptide based immunoassay in screening sera for anti-TTV antibodies. Comparison of the immunoassay developed using expressed N22 peptide with established PCR method for TTV-DNA detection showed good coherence between TTV-DNA and presence of anti-TTV antibodies in the sera analysed.ConclusionsThis concludes that TTV N22 region may be expressed and safely used as antigen for blot assay to detect anti-TTV antibodies in sera.
The present review describes the current status of multiplex quantitative real time polymerase chain reaction (qPCR) assays developed and used globally for detection and subtyping of hepatitis viruses in body fluids. Several studies have reported the use of multiplex qPCR for the detection of hepatitis viruses, including hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). In addition, multiplex qPCR has also been developed for genotyping HBV, HCV, and HEV subtypes. Although a single step multiplex qPCR assay for all six hepatitis viruses, i.e., A to G viruses, is not yet reported, it may be available in the near future as the technologies continue to advance. All studies use a conserved region of the viral genome as the basis of amplification and hydrolysis probes as the preferred chemistries for improved detection. Based on a standard plot prepared using varying concentrations of template and the observed threshold cycle value, it is possible to determine the linear dynamic range and to calculate an exact copy number of virus in the specimen. Advantages of multiplex qPCR assay over singleplex or other molecular techniques in samples from patients with co-infection include fast results, low cost, and a single step investigation process.
The present study describes the cloning and expression of ORF-2 region of TTV genome and the use of expressed peptide in developing immunoassay for detection of anti-TTV antibodies in serum. Presence of TTV-DNA in serum was detected by PCR amplifying N-22 region of ORF-1 of TTV genome. This was followed by genotyping of TTV by RFLP using N-22 amplicon. Using genotype-1 positive serum as the source of TTV, the ORF-2 region was amplified by PCR and subsequently cloned and expressed in pET-19b vector. The expressed protein, identified as 20 kDa protein on SDS-PAGE gel, was purified by affinity chromatography and then used as antigen to develop western blot assay for detection of anti-TTV antibodies in serum. Analysis of sera for anti-TTV antibodies and their comparison with presence of TTV-DNA, produced encouraging results. There was a good relation between presence of anti-TTV and TTV-DNA in these sera samples. Anti-TTV antibodies could be detected in all TTV-DNA positive sera irrespective of the presence of TTV-genotype. This investigation demonstrates that ORF-2 peptide may be used in developing immunoassay for identification of TTV infection.
Aims: This study describes an immunoassay to detect anti-torque teno virus (TTV) antibodies using a peptide obtained from expression of the N22 region of TTV genotype 2. Methods: The N22 region (∼500 bp) of TTV genotype 2 was cloned in a pET-28a(+) vector and expressed in ZYM-5052 autoinduction medium. Following metal affinity chromatography, a purified polypeptide was used as an antigen for the development of an immunoassay to detect anti-TTV antibodies in human sera. Results: Recombinant protein (∼25-kDa) was obtained after 24 h of incubation at 25°C in ZYM-5052 autoinduction medium. A blot assay developed using this polypeptide as an antigen and TTV-positive sera as the primary antibody produced a distinct spot on the nitrocellulose membrane. Serum samples from 36 of 42 patients with renal disease and 29 of 48 patients with liver diseases produced a positive signal using this immunoassay. Simultaneously, 18 of 48 healthy controls were also detected to be positive for anti-TTV antibodies. These results were found to be comparable with TTV detection using PCR, and the assay showed a high sensitivity and specificity (i.e., 97.44 and 91.67%, respectively). Moreover, this assay could detect TTV infection irrespectively of the genotype, including cases of mixed infection. Conclusion: The present immunoassay using the N22 expression product may be used as an alternative to PCR to detect TTV infection in large populations.
Background: Viral hepatitis is a major cause of liver diseases and poses a serious public health problem throughout the world including India.Objectives: Present study was planned to investigate the current status of viral hepatitis in patients with different liver and renal diseases.Methods: A total number of 1043 patients, selected from an adult population with both the sexes, were included in this study plan. After clinical examination, their sera were analyzed for the presence of different hepatitis viral markers. The diagnosis of acute infection was based on the presence of IgM type antibody for hepatitis A, B, D & E infections. HCV-RNA or total anti-HCV was used for the diagnosis of HCV infection. Results:We found the presence of hepatitis A virus (HAV) infection to be in 1-2% cases. Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections were recorded to be the major cause of acute and chronic liver diseases. At the same time, hepatitis E virus (HEV) was responsible for causing acute liver diseases without showing its presence in chronic liver diseases. Hepatitis D virus (HDV) infection was not detected in this group of patients. Occurrence of co-infection was recorded merely with HBV-HCV without any other type of co-infection. A clinical follow-up of patients having co-infection or super-infection demonstrated a relatively more derangement of liver functions in the patients. Conclusion:All types of hepatitis viral infections are prevalent in Indian patients' populations. The relative incidences of these infections vary slightly from place to place.
Background and Objectives: The variable response of hepatitis C virus (HCV) genotypes towards anti-viral treatment requires prior information on the genotype status before planning a therapeutic strategy. Although assays for typing or subtyping of HCV are available, however, a fast and reliable assay system is still needed. The present study was planned to develop a single-step multiplex quantitative real time polymerase chain reaction (qPCR) assay to determine HCV genotypes in patients' sera. Methods: The conserved sequences from 5′ UTR, core and NS5b regions of HCV genome were used to design primers and hydrolysis probes labeled with fluorophores. Starting with the standardization of singleplex (qPCR) for each individual HCV-genotype, the experimental conditions were finally optimized for the development of multiplex assay. The sensitivity and specificity were assessed both for singleplex and multiplex assays. Using the template concentration of 10 2 copies per microliter, the value of quantification cycle (Cq) and the limit of detection (LOD) were also compared for both singleplex and multiplex assays. Similarly, the merit of multiplex assay was also compared with sequence analysis and restriction fragment length polymorphism (RFLP) techniques used for HCV genotyping. In order to find the application of multiplex qPCR assay, it was used for genotyping in a panel of 98 sera positive for HCV RNA after screening a total number of 239 patients with various liver diseases. Results: The results demonstrated the presence of genotype 1 in 26 of 98 (26.53%) sera, genotype 3 in 65 (66.32%) and genotype 4 in 2 (2.04%) sera samples, respectively. One sample showed mixed infection of genotype 1 and 3. Five samples could not show the presence of any genotype. Genotypes 2, 5 and 6 could not be detected in these sera samples. The analysis of sera by singleplex and RFLP indicated the results of multiplex to be comparable with singleplex and with clear merit of multiplex over RFLP. In addition, the results of multiplex assay were also found to be comparable with those from sequence analysis. The sensitivity, specificity, Cq values and LOD values were compared and found to be closely associated both for singleplex and multiplex assays. Conclusion: The multiplex qPCR assay was found to be a fast, specific and sensitive method that can be used as a technique of choice for HCV genotyping in all routine laboratories.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.