Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultures of MDCK cells exposed to trypsin were as efficient as cultures of rhesus monkey kidney cells for detecting influenza virus, both in dilutions of infected allantoic fluids and in nose and throat swabs. We suggest that the MDCK cell/trypsin system provides a satisfactory alternative to monkey kidney cultures for the isolation of influenza viruses from clinical specimens.
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PMID:The use of a continuous cell line for the isolation of influenza viruses. 31 Jul 38

This study deals with the requirements for target cell recognition by influenza A virus-specific cytotoxic T lymphocytes (CTL). H-2-identical cells were incubated with infectious or UV light-inactivated influenza A virus expressing either cleaved or uncleaved hemagglutinin (HA). Thereafter, the treated cells were tested in a 4-h 51Cr assay for susceptibility to CTL-mediated cytolysis. Regardless whether the influenza virus was infectious, virions expressing cleaved HA were efficient in target cell formation. In contrast, cells incubated with either active or UV-inactivated virions expressing uncleaved HA were not lysed by virus-specific CTL. Yet, after mere trypsin-mediated cleavage of the HA of cell-absorbed viroins, strong cytolysis could be observed. On the other hand, solubilization of the envelope lipid bilayer by ethylether abolished the capacity of the remaining HA to induce target cell formation. The results clearly suggest that mere absorption of virions to the membrane of cells, which is performed by virus with uncleaved HA, is insufficient for target cell formation. For this, both cleaved HA and an intact envelope appear to be crucial. We conclude that fusion of the virion into the cell membrane is essential for target cell formation.
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PMID:Influenza virus-specific T cell-mediated cytotoxicity: integration of the virus antigen into the target cell membrane is essential for target cell formation. 31 3

We report the first isolation of influenza virus from muscle in a man with myoglobinuria and acute polymyositis. Influenza virus was isolated from cultures of Madin Darby bovine kidney and primary rhesus monkey kidney cells inoculated with muscle homogenates in the presence of trypsin; the virus was identified by neutralization and hemagglutination inhibition studies using influenza B/Lee antiserum. Viral plaque assay was performed with Madin Darby canine cells. Viral antigen was also detected by specific immunofluorescence in muscle, and myxovirus-like particles were seen in subsarcolemmal vacuoles by electronmicroscopy. The pathologic findings were similar to those of childhood dermatomyositis, except for a large proportion of necrotic muscle fibers. The evidence suggests that the pathogenesis of influenzal polymyositis in this patient involved direct viral infection of muscle.
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PMID:Isolation of influenza virus from muscle in myoglobinuric polymyositis. 38 94

In the course of research of the possibilities of adapting the influenza virus serotype A 2-Pol 29/69 to BHK-21 and CHL cells its production was established in the investigated combinations. An indication of virus replication is an increase in infectious and haemagglutination titres within 48 h after infection and gradual increase in haemadsorption. Observation of the influence of trypsin (10 microgram/ml) indicates that trypsin increases the capability of viruses to penetrate the cells. The cytopathic effect was not observed in cells infected with influenza virus.
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PMID:Adaptation of the influenza virus A2-pol 29/69 to the cells of the Chinese hamster lung (CHL) and to the cells BHK-21. 53 14

The genetic basis for the distinctive capacity of influenza A/WSN/33 (H0N1) virus (WSN virus) to produce plaques on bovine kidney (MDBK) cells was found to be related to virus neuraminidase. Recombinant viruses that derived only the neuraminidase of WSN virus were capable of producing plaques, whereas recombinant viruses identical to WSN except for neuraminidase did not produce plaques. With viruses that do not contain WSN neuraminidase, infectivity of virus yields from MDBK cells was increased approximately 1,000-fold after in vitro treatment with trypsin. In contrast, no significant increase in infectivity was observed after trypsin treatment of viruses containing WSN neuraminidase. In addition, polyacrylamide gel analysis of proteins of WSN virus obtained after infection of MDBK cells demonstrated that hemagglutinin was present in the cleaved form (HA1 + HA2), whereas only uncleaved hemagglutinin was obtained with a recombinant virus that derived all of its genes from WSN virus except its neuraminidase. These data are in accord with the hypothesis that neuraminidase may facilitate production of infectious particles by removing sialic acid residues and exposing appropriate cleavage sites on hemagglutinin.
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PMID:Virulence factors of influenza A viruses: WSN virus neuraminidase required for plaque production in MDBK cells. 56 60

After polyadenylation in vitro of the influenza virus RNA segment which contains the coding information for the matrix protein, a cDNA copy can be made using the primer p(dT)8-dA and reverse transcriptase. The sequence of 166 nucleotides of the cDNA was determined by a modification [Brownlee, G. G. & Cartwright, E. M. (1977) J. Mol. Biol, 114, 93--117] of the plus/minus method [Sanger, F. & Coulson, A. R. (1975) J. Mol. Biol. 94, 441--481] and adaptation of the "dideoxy" method [Sanger, F., Nicklen, S. & Coulson, A. R. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 5463--5467] for sequencing DNA. The cDNA sequences is of the same sense as the mRNA for matrix protein and contains a potential initiating codon, d(ATG), at position 26--28. When matrix protein purified from virus particles was digested with chymotrypsin or trypsin and the amino acid compositions of separated peptides determined, one peptide containing nine amino acids found which had a composition corresponding to that predicted by the cDNA sequence following the first methionine codon, confirming that protein synthesis initiates at this position. The compositions of four other peptides matches those predicted from the nucleotide sequence. There is no processing of the N terminus of the protein before incorporation into the virus particle except for removal of the N-terminal methionine and addition of a "blocking" group on the resulting N-terminal serine residue.
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PMID:Nucleotide sequence coding for the N-terminal region of the matrix protein influenza virus. 57 97

JJ/50 and four other strains of influenza C virus grew in an established line of canine kidney (MDCK) cells. Multicycle virus growth was markedly enhanced by the addition of trypsin to the culture medium and these viruses could be passaged serially in this system. The addition of appropriate concentrations of trypsin to the agar overlay medium enabled plaquing of influenza C/JJ/50 virus. Titration by plaque assay on MDCK cells was more sensitive than that by intra-amniotic inoculation of fertile hens' eggs.
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PMID:The multiplication of an influenza C virus in an established line of canine kidney (MDCK) cells. 64 30

Interferon levels in nasal secretions of infants under one year of age, and hospitalized with lower repiratory tract disease, were measured during two respiratory infection seasons. In the first year serial secretions from 50 infants with respiratory syncytial virus infection were examined. Undetectable or low levels of interferon were found in all samples, and mean levels did not fluctuate significantly in relation to disease and recovery. This was in contrast to anti-RSV IgA, which appeared and increased in concentration as virus shedding decreased and stopped. In the second year secretions were obtained from nine infants with influenza A virus infection as well as from 13 with RSV. All those with influenza developed measurable interferon in secretions (geometric mean titer 138 units/ml), which was acid and heat stable, and trypsin sensitive (type I interferon). RSV infection again stimulated very low levels (geometric mean 5 units/ml). The lack of correlation of interferon concentration with cessation of RSV shedding suggests either that it is not involved in recovery or that low levels are adequate. On the other hand, it appears that the young infant is fully capable of a brisk local interferon response, at least to infection by influenza A.
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PMID:Interferon in nasal secretions from infants with viral respiratory tract infections. 65 Mar 42

Influenza virus type C could be propagated to high yield in primary chick embryo kidney cell culture (PCEK) provided that trypsin (2 microgram/ml) was used as a medium supplement. The virus could also be titrated by plaque assay using PCEK host cells and influenza C virus that had been plaque-purified in PCEK cells could then be serially passaged to high titer using the allantoic route of 10--11-day-old embryonated eggs.
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PMID:Growth characteristics of influenza virus type C in avian hosts. Brief report. 73 97

The possibility of the proteolotic enzymes incorporation into the viral particle and the changes in proteolysis during interaction of the purified influenza virus (A2 Hong-Kong (1)68) with isolated plasmatic membranes of the mice lungs were studied. The presence of trypsin-like protease in the purified influenza virion was found. It is established that proteolysis intensifies during a short-term interaction of the isolated plasmatic membranes with the influenza virus.
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PMID:[Proteolysis intensification during influenza virus interaction with plasma membrane of sensitive cells]. 74 93


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