ABSTRACT
Hepatitis C virus (HCV) infection is a common cause of chronic hepatitis and is currently treated with alpha interferon (IFN-α)-based therapies. IFN-induced cell membrane protein BST2 (also known as CD317, HM1.24 or tetherin) has been reported to tether a broad range of lipid-enveloped viruses on cell surfaces. However, whether HCV is sensitive to BST2 remains controversial. Here we established a Huh7.5-BST2-TO cell line, in which BST2 expression is regulated by tetracycline. Our results showed that the effect of BST2 on inhibiting HCV production was dependent on its expression level. Highly expressed BST2 reduced the yield of cell-free HCV virions but did not affect the efficiency of HCV infection and genome replication. Co-localization of HCV core protein and BST2 was detected by immunofluorescence in certain cells with high expression, but not in cells with low BST2 expression. Furthermore, inhibition of IFN-α induced BST2 expression in Huh7.5 cells by siRNA technology slightly reduced the antiviral response of the cytokine against HCV, but only at low IFN-α concentration. While overexpression of BST2 inhibited HCV replication in this system, BST2 is therefore not likely to be a major contributor to the antiviral effect of IFN-α.
Subject(s)
Antigens, CD/metabolism , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/virology , Hepacivirus/physiology , Liver Neoplasms/metabolism , Liver Neoplasms/virology , Virus Replication , Antigens, CD/genetics , Carcinoma, Hepatocellular/genetics , Cell Line, Tumor , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , Hepacivirus/genetics , Humans , Liver Neoplasms/genetics , Protein Transport , Viral Proteins/genetics , Viral Proteins/metabolismABSTRACT
OBJECTIVE: To understand the genotypes of human metapneumovirus (hMPV) and the genetic character of hMPV attachment protein G sequence in Hunan, China. METHODS: 232 nasopharyngeal aspirates (NPA) samples from hospitalized children with acute respiratory infections were collected from Hunan, China in 2005. HMPV was detected. The full length of G glycoprotein genes were amplified and sequenced. Bioinformatics soft-wares were employed to analyze the sequences. RESULTS: 17/232 (7.3%) were showed hMPV positive. And co-infection rate with other viruses is 35%. The diagnoses of these hMPV positive cases are pneumonia, bronchiolitis and bronchopneumonia. Phylogenetic analysis for G genes from 13 hMPVs revealed the existence of four major subgroups: A1, A2, B1, B2 in Hunan, China in 2005. There are four types of sequence lengths of hMPV G glycoprotein, which are 711, 675, 660, 696nt. It is different in potential N-linked glycosylation sites and number of cysteine residues among these hMPVs of Hunan, China and Beijing, China. Also it is different from those in Japan and North America. CONCLUSION: The investigation of hMPV from Hunan, China in 2005 revealed the high speed of genetic variation and the marked character of geographic epidemic differences.
Subject(s)
Glycoproteins/genetics , Metapneumovirus/genetics , Respiratory Syncytial Virus Infections/virology , Viral Proteins/genetics , Amino Acid Sequence , Child , China/epidemiology , Genotype , Glycoproteins/classification , Humans , Metapneumovirus/classification , Metapneumovirus/isolation & purification , Molecular Sequence Data , Phylogeny , RNA, Viral/genetics , Respiratory Syncytial Virus Infections/epidemiology , Sequence Homology, Amino Acid , Viral Proteins/classificationABSTRACT
Human bocavirus (HBoV) is a new parvovirus first discovered in 2005, which is associated with acute respiratory infection. Analysis of sequence homology has revealed that a putative phospholipase A2 (PLA2) motif exists in the VP1 unique region of HBoV. However, little is known about whether the VP1 unique region of HBoV has PLA2 enzymatic activity and how these critical residues contribute to its PLA2 activity. To address these issues, the VP1 unique region protein and four of its mutants, were expressed in Eschericha coli. The purified VP1 unique protein (VP1U) showed a typical Ca2+-dependent secreted PLA2-like (sPLA2) activity, which was inhibited by sPLA2-specific inhibitors in a time-dependent manner. Mutation of one of the amino acids (21Pro, 41His, 42Asp or 63Asp) in VP1U almost eliminated the sPLA2 activity of HBoV VP1U. These data indicate that VP1U of HBoV has sPLA2-like enzymatic activity, and these residues are crucial for its sPLA2-like activity. Potentially, VP1U may be a target for the development of anti-viral drugs for HBoV.
Subject(s)
Bocavirus/enzymology , Phospholipases A2/metabolism , Viral Proteins/metabolism , Acetophenones/pharmacology , Amino Acid Motifs , Amino Acid Sequence , Calcium/metabolism , Cloning, Molecular , Humans , Molecular Sequence Data , Mutation , Parvoviridae Infections/metabolism , Parvovirus B19, Human/enzymology , Phospholipase A2 Inhibitors , Phospholipases A2/genetics , Terpenes/pharmacology , Viral Proteins/genetics , Viral Proteins/isolation & purificationABSTRACT
The full-length genome of one human bocavirus (HBoV) and the VP1 sequences of nine HBoV were amplified from patients' samples by PCR, cloned into pGEM-T vector separately, and sequenced. In this study, the one full length gemome and nine VP1 sequences of HBoV were aligened with 14 sequences of Parvoviruses which were canonical exemplars in Parvovirinae. Phylogenetic analysis showed that HBoV capsid sequences positioned closely to B19 parvovirus, although they positioned far in phylogenetic tree based on full length genome. Many similarities were found between HBoV and B19 in capsid by alignment on secondary structural elements. Because both B19 and HBoV are the only Parvoviruses that infect mankind, so study on HBoV may be used for reference to B19 which had been studied for about 30 years. By analysis of mutational sites, HBoV capsid protein showed a highly conserved secondary structural elements, but highly active in VP1-U, leading end of VP2 and insertions between the strands of the betaG-H. This cued that HBoV inclined to immune evasion and infectant adaptive faculty.
Subject(s)
Bocavirus/genetics , Capsid Proteins/genetics , Genome, Viral , Amino Acid Sequence , Base Sequence , Bocavirus/classification , Capsid Proteins/chemistry , Cloning, Molecular , Conserved Sequence , Humans , Molecular Sequence Data , Phylogeny , Polymerase Chain ReactionABSTRACT
OBJECTIVE: To study the clinical characteristics of human bocavirus (HBoV) among children and to understand the association of HBoV with human diseases. METHOD: Totally 148 nasopharyngeal aspirate (NPA) samples were collect from hospitalized children with acute respiratory infection during Oct. 2005 to Feb. 2006. Two serum samples were obtained from HBoV positive patients. PCR was used to assay all these samples and PCR products were sequenced. RESULT: HBoV was positive in 11 of 148 NPA samples. The positive rate was 7.4 percent. The serum samples of HBoV infected patients showed that serum contained HBoV by PCR assay. All these HBoV positive patients had the clinical symptoms of bronchitis, bronchopneumonia and pneumonia. Some patients had diarrhea. CONCLUSION: All patients infected with HBoV had upper and lower respiratory tract infections. HBoV is a probable important pathogen of upper and lower respiratory tract infection. The HBoV could cause viremia. In addition, some HBoV patients had diarrhea. HBoV infection probably could also result in intestinal disease and other related symptoms.
Subject(s)
Bocavirus/isolation & purification , Parvoviridae Infections/virology , Respiratory Tract Infections/virology , Bocavirus/genetics , Child , Child, Preschool , DNA, Viral/blood , Female , Humans , Infant , MaleABSTRACT
A newly identified parvovirus, human bocavirus (HBoV), was found in 21 (8.3%) of 252 nasopharyngeal aspirates from hospitalized children with lower respiratory tract infection in Hunan Province, People's Republic of China. Viral loads were 10(4) to 10(10) copies/mL. Phylogenetic analysis of the VP1 gene showed a single genetic lineage of HBoV worldwide.
