SEARCH · PubMed Health

Results for “Virus Replication”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources

PubMed1979

Cell fusion for genetic analysis of two nonconditional Rous sarcoma virus replication mutants.

Procedures for characterizing replication-defective viruses in nonpermissive mammalian cells were developed and applied to three nonvirogenic Rous sarcoma virus (RSV)-transformed mammalian cell lines--B4, a line of Bryan virus-transformed hamster cells, and two SRD-RSV transformed rat cell lines, LR3/1 and LR3/2. Cell fusion was used to study virus complementation. The three cell lines (i) fused with helper virus-infected chicken cells and the host range of the rescued virus examined, (ii) tested for complementation by fusion with chicken cells exhibiting various patterns of endogenous virus expression, (iii) fused with chicken cells infected with the temperature-sensitive replication mutant LA334 and assayed for complementation at permissive and nonpermissive temperatures, and (iv) tested for complementation of defective viruses in other RSV-transformed mammalian cell lines by fusing pairs of nonvirogenic cell lines and permissive chicken cells. Based upon these complementation studies, we concluded that B4 virus is defective only in the env gene, LR3/) virus is an absolute mutant in the gag and/or pol genes, and LR3/2 virus is a leaky env mutant. Clones of LR3/1 and LR3/2 virus-infected chicken cells were established, and the results obtained from the characterization of these viruses in permissive avian cells substantiates the conclusions reached in the fusion-rescue studies.

Animals↗

PubMed1981

Suppression of dengue virus replication in vitro by rimantadine hydrochloride.

The effects of rimantadine on dengue virus replication were examined in a variety of tissue culture systems. The growth of dengue virus type 2 in human peripheral blood leukocytes (PBL) was completely suppressed when rimantadine was included in the culture medium at a concentration of 25 microgram/ml. Similarly, rimantadine caused a significant inhibition of dengue virus replicaton in cultures of rhesus monkey PBL. Addition of drug into virus-infected LLC-MK2 cell cultures caused a decrease in the production of all four types of dengue virus. Maximal inhibition of dengue virus replication by rimantadine was observed when the drug was added immediately following the viral adsorption period. Rimantadine did not induce may cytopathic effects on either LLC-MK2 cells or PBL at concentrations less than 75 microgram/ml. These findings demonstrate that rimantadine is an effective inhibitor of dengue virus replication in vitro, and indicate a need for further examination of the efficacy of rimantadine against severe dengue virus disease.

Adamantane↗

PubMed1998

Comparison of RNA hybridization, hemagglutination assay, titration of infectious virus and immunofluorescence as methods for monitoring influenza virus replication in vitro.

Rapid and sensitive methods for the monitoring of influenza virus replication in vitro are needed to address several research questions. Four methods based on different principles were compared: the hemagglutination (HA) assay, the measurement of virus infectivity titers in culture supernatants, the enumeration of infected cells by immunofluorescence and RNA hybridization techniques using digoxigenin (DIG) labeled RNA probes. To this end, MDCK cells were infected at different multiplicities of infection (moi) with a recent influenza A virus (A/Netherlands/18/94 H3N2) and the kinetics of virus replication were monitored with these four assays. At high moi, virus released into the culture supernatant of infected cells was detected by the HA assay 12 h post infection, whereas at lower moi (< or = 0.01) the first HA activity was not detected before 24 h post infection. The measurement of infectious viruses in the culture supernatant proved to be more sensitive, since 4-12 h post infection newly produced virus was detected depending on the moi used. This finding was in agreement with results obtained by the immunofluorescence assay using an antibody preparation specific for the nucleoprotein: single infected cells could be detected as early as 4 h post infection. At this time point, positive signals were also obtained when mRNA/cRNA specific hybridization was carried out for the NP gene segment, but not for viral NP RNA or RNA specific for the hemagglutinin, which were only detected at later time points after infection. Thus, besides direct measurement of infectious virus and immunofluorescence, RNA hybridization proved to be a sensitive assay for monitoring influenza virus replication in vitro.

Animals↗

PubMed1990

Hepatitis B virus and hepatitis D virus replication in HBsAg-positive fulminant hepatitis.

Hepatitis B virus DNA and hepatitis D virus RNA, the most sensitive markers of hepatitis B and hepatitis D virus replication, were sought by molecular hybridization with radioactive probes in serial serum samples from 29 consecutive patients with HBsAg-positive fulminant hepatitis. Nineteen patients had evidence of hepatitis D virus infection, as assessed by the presence in serum of delta antigen, anti-delta antibodies, or both. Hepatitis B virus DNA was found in only two patients: one was a chronic HBsAg carrier with hepatitis D virus superinfection and the other had fulminant hepatitis caused by hepatitis B and hepatitis D coinfection. Hepatitis D virus RNA was detected in three patients: two with hepatitis B and hepatitis D coinfection and also in the HBsAg carrier with positive hepatitis B virus DNA and hepatitis D virus superinfection. None of 10 patients with hepatitis B virus infection alone had detectable viral nucleic acids in serum. Overall, viral nucleic acids were detected in the sera of 4 of the 29 patients (14%). Hepatitis D virus antigenemia did not indicate hepatitis D virus replication because hepatitis D virus RNA was not detected in 9 of 12 patients with hepatitis D virus antigen in their sera. The low frequency of viral replication found in fulminant hepatitis B or D may explain the low recurrence rate of viral hepatitis in patients with fulminant hepatitis who have received liver transplantations.

Adolescent↗

PubMed2007

An RNA-binding protein, hnRNP A1, and a scaffold protein, septin 6, facilitate hepatitis C virus replication.

Hepatitis C virus (HCV) is a positive-sense single-stranded RNA virus. NS5b is an RNA-dependent RNA polymerase that polymerizes the newly synthesized RNA. HCV likely uses host proteins for its replication, similar to other RNA viruses. To identify the cellular factors involved in HCV replication, we searched for cellular proteins that interact with the NS5b protein. HnRNP A1 and septin 6 proteins were identified by coimmunoprecipitation and yeast two-hybrid screening, respectively. Interestingly, septin 6 protein also interacts with hnRNP A1. Moreover, hnRNP A1 interacts with the 5'-nontranslated region (5' NTR) and the 3' NTR of HCV RNA containing the cis-acting elements required for replication. Knockdown of hnRNP A1 and overexpression of C-terminally truncated hnRNP A1 reduced HCV replication. In addition, knockdown of septin 6 and overexpression of N-terminally truncated septin 6 inhibited HCV replication. These results indicate that the host proteins hnRNP A1 and septin 6 play important roles in the replication of HCV through RNA-protein and protein-protein interactions.

3' Untranslated Regions↗

PubMed1980

Interferon production and virus replication in lymphoblastoid cells infected with different viruses.

A semicontinuous infection system was used to test viral replication and interferon induction in lymphoblastoid cells: measles virus, Newcastle disease virus (NDV), Sendai virus, human parainfluenza virus (type II and III), Semliki forest virus (SFV) and Vesicular stomatitis virus (VSV). With the exception of Sendai virus, all viruses replicated in the Namalva cell line. Only measles virus was able to induce high levels of interferon. Three other cell lines, NC37, Raji (TK+-variant) and Raji (TK--variant) were tested using measles virus as inducer. The interferon yields from these cells were inferior to those obtained from Namalva cells.

Cell Line↗

PubMed2003

[Development of the cDNA chip for SARS virus and a primary study on the possible molecular mechanism of interferon alpha2b inhibiting the SARS virus replication].

BACKGROUND: To study the molecular mechanism of interferon alpha2b(IFNalpha2b) inhibiting the SARS virus replication. SARS-associated coronavirus (SARS virus) cDNA chip was developed and applied to detect the virus RNA transcription levels in the interferon-treated and untreated cell cultures, and the mechanism of anti-SARS virus activity of interferon alpha2b in cell culture system was explored. METHODS: SARS virus cDNA chip was prepared by comparing the published SARS virus genome sequence, and the cDNA chip was used to study the interferon alpha2b function during SARS virus replication. RESULTS: SARS virus cDNA chip was successfully prepared by using PCR method. The results showed that the cDNA chip could be used to detect the viral RNA transcription level. Interferon alpha2b could inhibit almost all the SARS virus gene transcription. An unknown gene at the position 28130-28426 bp, named as U gene, may play an important role during the viral replication. CONCLUSION: A SARS virus whole genome cDNA chip was established. It could be used to study the virus molecular biology and antiviral drug screening. The results also showed that interferon alpha2b could inhibit almost the whole virus gene transcription by using the cDNA chip.

Humans↗

PubMed2001

Inhibition of porcine reproductive and respiratory syndrome virus by interferon-gamma and recovery of virus replication with 2-aminopurine.

Porcine reproductive and respiratory syndrome virus (PRRSV) belongs to a group of RNA viruses that establish persistent infections. A proposed strategy for evading immunity during persistent PRRSV infection is by preventing the induction of IFN activity in pigs and/or by blocking the activation of antiviral proteins in permissive cells. IFN-gamma mRNA expression was observed in the lymph nodes and lungs of pigs infected with wild-type PRRSV strain SDSU-23983. Pretreatment of MARC-145 cells with IFN-gamma inhibited wild-type (SDSU-23983 P6) and culture-adapted (SDSU-23983 P136) PRRS viruses in a dose-dependent manner and at relatively low concentrations. The effect of IFN-gamma on virus replication included reductions in the number of infected cells, virus yield, and RNA content in single cells. Virus replication was partially restored by the addition of 2-aminopurine (2-AP), an inhibitor of dsRNA inducible protein kinase (PKR). The addition of 2-AP also restored the viral RNA content per cell to near normal levels, suggesting that inhibition of viral RNA synthesis was through PKR. The principal difference between P6 and P136 isolates was the recovery of P136 replication with lower concentrations of 2-AP. Immunostaining with anti-PKR antibody showed a redistribution of PKR from the cytoplasm into nucleoli of infected cells.

2-Aminopurine↗

PubMed1977

Phosphonoacetic acid-resistant mutants of herpes simplex virus: effect of phosphonoacetic acid on virus replication and in vitro deoxyribonucleic acid synthesis in isolated nuclei.

Phosphonoacetic acid (PAA) inhibits the replication of herpes simplex virus in BSC-1 cells and the in vitro synthesis of deoxyribonucleic acid (DNA) in isolated nuclei. Phosphonopropionic acid at a concentration of 100 mug/ml had no effect on herpes simplex virus replication. PAA-resistant mutants were obtained at a rate of 1 in 10(4) plaque-forming units after 5-bromodeoxyuridine mutagenization of the virus. These mutants replicate in BSC-1 cells in the presence of 100 mug of PAA per ml and induce a PAA-resistant DNA polymerase that synthesizes DNA in vitro in the presence of PAA.

Acetates↗

PubMed2004

Innate immune responses and control of acute simian immunodeficiency virus replication in the central nervous system.

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) can invade the central nervous system (CNS) during acute infection but virus replication is apparently controlled because clinical and pathological manifestations of CNS disease in HIV/SIV-infected individuals usually present later in infection, coincident with immunosuppression and acquired immuno-deficiency syndrome (AIDS). Using an established SIV/macaque model of HIV dementia, the authors recently demonstrated that acute virus replication is down-regulated (to undetectable viral RNA levels) in the brain, but not the periphery, as early as 21 days post inoculation (p.i.). Viral DNA levels in the brain remain constant, suggesting that infected cells persist in the CNS and that replication is inhibited largely at a transcriptional level. In vitro, active replication of HIV in macrophages can be inhibited by treatment with interferon (IFN)beta via a mechanism involving induction of a dominant-negative form of the transcription factor C/EBP (CCAAT/enhancer-binding protein)beta. Because macrophages are the primary cell types infected with HIV/SIV in the CNS and HIV replication in macrophages requires C/EBP sites within the viral long terminal repeat (LTR), the authors considered the possibility that suppression of C/EBP-dependent transcription contributes to the mechanism by which acute HIV/SIV replication is inhibited in the CNS. Here, the authors report that IFNbeta can also inhibit ongoing SIV replication in macaque macrophages in vitro. Further, the authors demonstrate that IFNbeta levels in the brain increase between 7 and 21 days p.i. in parallel with increased expression of the dominant-negative isoform of C/EBPbeta. These results suggest that innate immune responses involving IFNbeta may contribute to the mechanism(s) controlling acute SIV replication in the CNS.

Acute Disease↗

PubMed1995

Experimental African swine fever: apoptosis of lymphocytes and virus replication in other cells.

In order to determine the cause of cellular death of lymphocytes in pigs with acute African swine fever and the relationships between African swine fever virus (ASFV) and interstitial cells, ten pigs were inoculated with a highly virulent strain of ASFV (Malawi '83) and samples taken for ultrastructural study of hepatic and renal interstitial tissues. We demonstrated death by apoptosis of lymphocytes and virus replication in fibroblasts, smooth muscle cells and endothelial cells in the interstitial tissues of pigs inoculated with ASFV. From day 5 onwards, apoptotic lymphocyte and intense virus replication in hepatic interstitial macrophages and fibroblasts were observed. By day 7, apoptotic lymphocytes and virus replication in macrophages, interstitial capillary endothelial cells and fibroblasts in the kidney were observed. Virus replication was also seen in smooth muscle cells of hepatic and renal arterioles and venules. Our results suggest that mononuclear phagocyte system (MPS) cell activation, and the resulting release of cytokines, could induce apoptosis of lymphocytes and virus replication in non-MPS cells.

African Swine Fever↗

PubMed1995

The vif gene is essential for efficient replication of caprine arthritis encephalitis virus in goat synovial membrane cells and affects the late steps of the virus replication cycle.

Complex retrovirus genomes contain a variable number of accessory genes, among which is the vif gene. We investigated in vitro the role of the vif gene of caprine arthritis encephalitis virus (CAEV) by studying the phenotype of five vif mutants after infection of primary goat synovial membrane (GSM) cells and blood-derived monocytes/macrophages. Any deletion introduced into the vif gene resulted in slow and low viral replication and production of virions with an infectious titer lower than that of wild-type viral particles. The wild-type phenotype could be restored by the trans expression of the vif gene in a complementation assay. Quantitative PCR and reverse transcription-PCR analyses were performed in order to determine which stage of the replicative cycle was impaired by the vif deletion. Our results demonstrated that CAEV Vif did not act at the level of reverse transcription or transcription but rather at the late stage of virus formation and/or release, as lower amounts of virus were produced after a single replicative cycle. The vif-deleted CAEV produced after 24 h of infection was still able to infect GSM cells, indicating that the vif gene is not essential for virus infectivity but is required for efficient virus production.

Amino Acid Sequence↗

PubMed1975

Inhalatory infection of mice with influenza A0/PR8 virus. I. The site of primary virus replication and its spread in the respiratory tract.

The replication of influenza A0/PR8 virus started and continued simultaneously in all parts of the respiratory tract, without any preferential susceptibility of any area of the epithelial lining when the virus was administered to mice in a sublethal dose in the form of aerosol. After intranasal instillation, the initial virus replication in the lung tissue preceded by 4 to 8 hours the rise in infectious virus titre in the trachea and by 21-24 hours the rise in the virus titre in the nasal mucosa. Under conditions of aersol inhalation, the mice represent a suitable model for pathogenetic studies.

Aerosols↗

PubMed2002

Roles of uracil-DNA glycosylase and dUTPase in virus replication.

Herpesviruses and poxviruses are known to encode the DNA repair enzyme uracil-DNA glycosylase (UNG), an enzyme involved in the base excision repair pathway that specifically removes the RNA base uracil from DNA, while at least one retrovirus (human immunodeficiency virus type 1) packages cellular UNG into virus particles. In these instances, UNG is implicated as being important in virus replication. However, a clear understanding of the role(s) of UNG in virus replication remains elusive. Herpesviruses, poxviruses and some retroviruses encode dUTPase, an enzyme that can minimize the misincorporation of uracil into DNA. The encoding of dUTPase by these viruses also implies their importance in virus replication. An understanding at the molecular level of how these viruses replicate in non-dividing cells should provide clues to the biological relevance of UNG and dUTPase function in virus replication.

Animals↗

PubMed1998

Detection of intrahepatic hepatitis C virus replication by strand-specific semi-quantitative RT-PCR: preliminary application to the liver transplantation model.

BACKGROUND/AIMS: Although the hepatitis C virus infection recurs in virtually all patients after liver transplantation, up to 50% of patients may not have histological recurrent hepatitis 1 year after liver transplantation. To study the relationship between hepatitis C virus infection and liver disease after liver transplantation, we compared the intrahepatic hepatitis C virus replication levels with the liver histopathology among liver transplant recipients. METHODS: The intrahepatic negative-strand HCV RNA (i.e. the putative hepatitis C virus replication intermediate RNA) was evaluated by a semi-quantitative, strand-specific reverse transcriptase-polymerase chain reaction in 44 liver specimens from 23 patients with hepatitis C virus reinfection after liver transplantation. Results were compared with the time from liver transplantation, presence, grading and staging of the recurrent hepatitis, amount of hepatitis C virus antigens in the liver and serum HCV RNA levels. RESULTS: Negative-strand HCV RNA was detected in 42 liver specimens as early as 7 days after liver transplantation. Its titers correlated with the amount of intrahepatic hepatitis C virus antigens, but not with HCV RNA levels in serum. Levels of negative-strand HCV RNA in 19 specimens without hepatitis were comparable to those seen in 25 specimens with hepatitis (p=0.492), and were unrelated to the liver disease grading and staging scores. The intrahepatic hepatitis C virus replication could occasionally precede the recurrence of the hepatitis by several months. CONCLUSIONS: Molecular evidence has been obtained for intrahepatic hepatitis C virus replication occurring early after liver transplantation. The level of replication is not correlated with the development of recurrent hepatitis, suggesting that hepatitis C virus may replicate without inducing morphological evidence of liver damage.

Adult↗

PubMed1978

Phytohemagglutinin enhancement of dengue-2 virus replication in nonimmune rhesus monkey peripheral blood leukocytes.

Phytohemagglutinin treatment of peripheral blood leukocytes from dengue nonimmune monkeys enhanced dengue-2 virus replication. Enhancement was due primarily to an increase in the number of infected cells. Destruction of mononuclear phagocytes with silica did not significantly inhibit virus replication in phytohemagglutinin-treated cultures. Pokeweed mitogen, concanavalin A, and streptolysin O stimulated increased deoxyribonucleic acid synthesis in monkey leukocytes but did not enhance virus replication. None of the mitogens significantly affected virus replication in cultures of dengue-immune monkey peripheral blood leukocytes.

Animals↗

PubMed1983

The relationship between prostaglandins and virus replication: endogenous prostaglandin synthesis during infection and the effect of exogenous PGA on virus production in different cell lines and in persistently infected cells.

African Green Monkey Kidney cells were shown to normally synthesize immunoreactive PGE1. Infection of these cells with Sendai virus did not alter rates of PGE1 synthesis, while it stimulated interferon production. PGAs, that we have previously shown to be potent inhibitors of Sendai virus replication in this system, at the same dose (4 micrograms/ml), also strongly inhibited the replication of this virus in HEp-2 cells and in VERO cells, a monkey kidney cell line that does not produce interferon. PGA1 was found to be effective in several cell and virus models, suggesting a broad spectrum of antiviral actions. Finally, we confirmed the observation that PGA1-treatment prevents the establishment of a "carrier state" by Sendai virus, and PGA1-cured cells did not show any sign of persistent infection for periods as long as 110 days after Sendai infection. Attempts to cure already established persistently infected cells were only partially successful.

Alprostadil↗

PubMedDate not supplied

Hepatitis B virus replication in acute hepatitis B, acute hepatitis B virus-hepatitis delta virus coinfection and acute hepatitis delta superinfection.

To evaluate the effect of hepatitis delta virus on the level of replication of hepatitis B virus and to assess the clinical significance that such an effect might have on the final outcome of the infection, the serological profile of hepatitis B virus DNA was investigated in 153 patients with acute or chronic hepatitis B virus infection with or without associated delta infection. Serum hepatitis B virus DNA was detected in 57% of patients with acute hepatitis B, 67% of those with acute hepatitis B virus-hepatitis delta virus coinfection and 25% of HBsAg carriers with hepatitis delta virus superinfection during the first week after the onset of symptoms. Patients with acute hepatitis B and those with acute hepatitis B virus-hepatitis delta virus coinfection did not differ significantly with respect to the serological profile of hepatitis B virus DNA and final clinical outcome. Within the group of HBsAg carriers with hepatitis delta virus superinfection, all patients who were initially negative for hepatitis B virus DNA developed chronic hepatitis delta virus infection, whereas 3 of the 4 patients with active hepatitis B virus infection at the time of superinfection showed transient inhibition of hepatitis B virus replication followed by termination of hepatitis delta virus infection in two patients. Therefore, although delta virus may inhibit the replication of hepatitis B virus among chronic HBsAg carriers, this effect is not readily apparent among patients with hepatitis B virus-hepatitis delta virus coinfection.

Acute Disease↗