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Results for “VIRAL INTERFERENCE”

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At least 955 records · Page 53Linked to original sources
PubMed1994

Interference between cold-adapted (ca) influenza A and B vaccine reassortants or between ca reassortants and wild-type strains in eggs and mice.

Interference between pairs of cold-adapted (ca) influenza A and B vaccine reassortant viruses and between ca influenza B reassortant viruses and wild-type influenza strain A/PR/8/34 was studied in embryonated eggs and/or in the respiratory tract of three strains of mice. Interference in eggs between ca A and B reassortants occurred after 2 days but was masked by later cycles of growth. When doses of 10(6) EID50 of the reassortant viruses B/60/32/R and A/47/6/R were administered to outbred mice, interference with the growth of A/47/6/R occurred in the turbinates; interference with the growth of B/60/32/R did not occur. However, interference with the growth of B/60/32/R was noted in the lungs of Balb/c mice after co-infection with 10(6) EID50 of both A/PR/8/34 and B/60/32/R. Interference did not occur when the dose of B/60/32/R was increased to 10(7) EID50 per mouse. When CBA mice were co-infected with 10(6) EID50 of both B/60/32/R and the influenza A ca reassortant R/34, or 10(6) EID50 of B/60/32/R,R/34 and A/Leningrad/134/57, interference did not occur. Interference could not be detected in mice following dual infection from serum responses to individual viruses.

Animals↗
PubMed1979

Inactivation by u.v.-irradiation of interfering herpes simplex virus particles: interference requires a functional genome.

The sensitivity of interfering herpes simplex virus (HSV) particles to u.v.-irradiation was studied in a virus stock of HSV-1 strain ANG that contained an excess of interfering over infectious particles. Following u.v.-irradiation, samples of this virus stock were assayed for their plaque-forming capacity and their capacity to interfere with the replication of unirradiated standard virus. Depending on the assay conditions, interfering particles appeared to be less, equally, or more sensitive to u.v. light than infectious particles. It is concluded that interference is a gene function of interfering particles rather than being exerted directly by structural constituents of these particles.

Animals↗
PubMed1986

The effect of colostrum-derived antibody on neo-natal transmission of caprine arthritis-encephalitis virus infection.

Two groups of 6 newborn goat kids were artificially fed colostrum containing antibody to caprine arthritis-encephalitis (CAE) virus, obtained from clinically affected does. Kids in group A were fed the colostrum from birth until 7 days of age, while kids in group B were fed colostrum from 1 to 3 days after birth for 7 days. Kids were fed cow's milk at all other times. Serum antibody resulting from the consumption of colostrum, detected by agar gel immunodiffusion (AGID) tests, lasted for up to 8 weeks in group A, but none was detected in group B. Four kids from each group became infected with CAE virus as demonstrated by the emergence of active immunity and by virus isolation procedures. It appeared that uptake of colostral antibody by group A did not prevent viral transmission, interfere with development of active immunity, or modify the outcome of the CAE virus infection.

Animals↗
PubMedDate not supplied

[Interference and its overcoming during the reproduction of 2 influenza A virus strains in an experiment].

The interference between two influenza A virus strains was investigated in vivo. In mixed infection of chick embryos or mice two results were observed: maximal reproduction of both strains or interference which resulted in a reduction of reproduction activity, antibody production, or virulence of one of the viruses. No interference was observed upon inoculation of two strains apathogenic for the study host combined with an equal concentration of an infectious virus.

Animals↗
PubMed2001

Double-stranded RNA-mediated interference with plant virus infection.

Double-stranded RNA (dsRNA) has been shown to play a key role as an inducer of different interference phenomena occurring in both the plant and animal kingdoms. Here, we show that dsRNA derived from viral sequences can interfere with virus infection in a sequence-specific manner by directly delivering dsRNA to leaf cells either by mechanical inoculation or via an Agrobacterium-mediated transient-expression assay. We have successfully interfered with the infection of plants by three viruses belonging to the tobamovirus, potyvirus, and alfamovirus groups, demonstrating the reliability of the approach. We suggest that the effect mediated by dsRNA in plant virus infection resembles the analogous phenomenon of RNA interference observed in animals. The interference observed is sequence specific, is dose dependent, and is triggered by dsRNA but not single-stranded RNA. Our results support the view that a dsRNA intermediate in virus replication acts as efficient initiator of posttranscriptional gene silencing (PTGS) in natural virus infections, triggering the initiation step of PTGS that targets viral RNA for degradation.

Gene Silencing↗
PubMed2003

Expression of hepatitis c virus proteins inhibits interferon alpha signaling in the liver of transgenic mice.

UNLABELLED: BACKGROUND & AIMS Hepatitis C virus (HCV) is a major cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma worldwide. The majority of patients treated with interferon alpha do not have a sustained response with clearance of the virus. The molecular mechanisms underlying interferon resistance are poorly understood. Interferon-induced activation of the Jak-STAT (signal transducer and activator of transcription) signal transduction pathway is essential for the induction of an antiviral state. Interference of viral proteins with the Jak-STAT pathway could be responsible for interferon resistance in patients with chronic HCV. METHODS: We have analyzed interferon-induced signal transduction through the Jak-STAT pathway in transgenic mice that express HCV proteins in their liver cells. STAT activation was investigated with Western blots, immunofluorescence, and electrophoretic mobility shift assays. Virus challenge experiments with lymphocytic choriomeningitis virus were used to demonstrate the functional importance of Jak-STAT inhibition. RESULTS: STAT signaling was found to be strongly inhibited in liver cells of HCV transgenic mice. The inhibition occurred in the nucleus and blocked binding of STAT transcription factors to the promoters of interferon-stimulated genes. Tyrosine phosphorylation of STAT proteins by Janus kinases at the interferon receptor was not inhibited. This lack in interferon response resulted in an enhanced susceptibility of the transgenic mice to infection with a hepatotropic strain of lymphocytic choriomeningitis virus. CONCLUSIONS: Interferon-induced intracellular signaling is impaired in HCV transgenic mice. Interference of HCV proteins with interferon-induced intracellular signaling could be an important mechanism of viral persistence and treatment resistance.

Animals↗
PubMed1980

BALB/c myeloma retroviruses have mink cell focus-inducing activity.

We have determined the in vitro host range of the cloned MO-21 and FL-1 murine myeloma retroviruses grown in SC-1 cells that were originally isolated from cloned MOPC-21 and FLOPC-1 BALB/c plasmacytoma cell lines. These viruses are able to replicate in murine (BALB/3T3, NIH/3T3) as well as numerous heterologous cell lines. These myeloma retroviruses also exhibit mink cell focus-inducing activity. MO-21 and FL-1 shared interference patterns with each other, but their replication was not interfered with by ecotropic, xenotropic, or amphotropic viruses. The lack of cross-interference with ecotropic or xenotropic viruses distinguishes these isolates from other mink cell focus-inducing viruses.

Animals↗
PubMed1992

Double antibody sandwich ELISA for the detection of rubella virus antigen.

We developed enzyme linked immunosorbent assay (ELISA) for the detection of rubella virus antigen, using two monoclonal antibodies, MC-7 and MC-22. The double antibody sandwich ELISA method was carefully standardized and found to be sensitive enough to detect as small as 2.5 ng protein of rubella virus. The infective titers by the double antibody sandwich ELISA closely related to those judged by interference of vesicular stomatitis virus in RK-13 cells. The method is simple, sensitive, and readily applicable to the detection of rubella virus.

Animals↗
PubMed1978

Quantitative analysis of defective interfering particles in infectious pancreatic necrosis virus preparations.

Infectious pancreatic necrosis virus exhibited an interference phenomenon that resulted in the survival of the infected cell with one hit kinetics. The responsible factor was found to co-purify with standard virus through a purification regime that employed two CsCl gradients and a sucrose gradient. This result suggested that a defective interfering (DI) viral particle was involved. It was possible to estimate the number of DI particles by a statistical method using the Poisson distribution that related cell survival to input DI/cell, which indicated that virus samples from dilute passage contained as many DI particles as samples from undiluted passage; this means that multiple undiluted virus passage did not increase the yield of DI particles. In isopycnic CsCl gradient centrifugation, the DI particles were found in a broad band superimposed over the standard virus peak and extending above it, such that the ratio DI/PFU varied from 0.3--20 in different fractions. These centrifugation methods did not completely separate DI particles from standard virus.

Animals↗
PubMed2005

The clinical features of respiratory syncytial virus: lower respiratory tract infection after upper respiratory tract infection due to influenza virus.

BACKGROUND: Respiratory syncytial virus (RSV) and influenza virus are the primary pathogens of respiratory tract infection. However, epidemics of influenza virus infection have been observed to interrupt RSV epidemics (termed an epidemiological interference effect). METHODS: At a clinic in Tsuna county, Hyogo prefecture, Japan, a total of 1262 outpatients under 6 years of age with lower respiratory tract infection due to RSV (RSV-LRTI) and upper respiratory tract infection due to influenza virus (FLU-URTI) in three successive winter seasons (1999-2000, 2000-2001 and 2001-2002) were analyzed. RESULTS: The RSV-LRTI epidemic and FLU-URTI epidemic overlapped in each season, but the RSV-LRTI epidemic peak preceded that of the FLU-URTI epidemic. Epidemiological interference between RSV and influenza virus was observed in the second and third season; the number of patients with RSV-LRTI began to decrease after the start of the FLU-URTI epidemic and recovered to some extent after the FLU-URTI epidemic passed its peak. There were no differences in onset age, male-to-female ratio and severity of RSV-LRTI in outpatients before and after the start of the FLU-URTI epidemic in all the three seasons. CONCLUSION: An epidemiological interference between RSV and influenza virus was observed in Tsuna county in two of the three winter seasons. However, there was no difference between the clinical features of the patients with RSV-LRTI before and after the start of the influenza virus infection epidemic. The data suggest that the clinical severity of RSV infection is not changed by the epidemiological interference effect of influenza virus infection epidemics.

Child, Preschool↗