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)

The replication of simian rotavirus SA11 in GMK cells and of bovine rotavirus in calf kidney cells was studied by electron microscopy. By 30 min post-inoculation (p.i.) SA11 virus was absorbed to the cell membrane in the absence of trypsin and became engulfed into the cell; clusters of viral particles were internalized also into cytoplasmic vacuoles. At 2 hr p.i., viral particles were seen in lysosomes and 6 hr p.i., the first progeny virus was found in the cisternae of endoplasmic reticulum (ER). Precursor virus particles budded from viroplasm into the cisternae of endoplasmic reticulum, where they became enveloped reaching a diameter of 80-90 nm. There was no difference between SA11 virus and bovine rotavirus. Although the budding of rotavirus particles is essential for acquiring of glycoproteins, the envelopment of capsids was transient. After stripping off the envelope, mature particles were formed 65-70 nm in diameter, consisting of either smooth or rough capsids. The final cytocidal stage of cell infection is described.
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PMID:Electron microscopic investigations of rotavirus morphogenesis in cell cultures. 614 93

LLC-MK2, GMK AH-1, BSC-1, and Vero cells were compared in titrations of recent isolates and laboratory strains of influenza A and B and parainfluenza types 1, 2, and 3 viruses. About the same titres, as determined by haemadsorption in cell cultures, were obtained in LLC-MK2, GMK AH-1, and BSC-1 cells when trypsin had been added to the medium, whereas the Vero cells were less sensitive to the influenza virus strains tested. Virus titres were usually low in the absence of trypsin. A laboratory strain of parainfluenza 2 virus reached about the same titres in medium without as in medium with trypsin, possibly owing to prior adaptation by passages in Vero cells. Comparative titrations of influenza A, and parainfluenza 1 and 3 viruses suggested the same susceptibility of LLC-MK2 cells with trypsin as of primary monkey kidney cells. Re-isolation experiments from 38 clinical specimens showed LLC-MK2 cells to be as efficient as primary monkey kidney cells for isolation of influenza and parainfluenza viruses, whereas the susceptibility of the other cell lines to clinical material has not yet been tested on a larger scale. It is concluded that a continuous line of monkey kidney cell culture may be acceptable as an alternative to primary monkey kidney cells for the isolation of influenza and parainfluenza viruses from patients.
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PMID:Susceptibility of continuous lines of monkey kidney cells to influenza and parainfluenza viruses in the presence of trypsin. 627 42

A large proportion of host cell-bound virions of poliovirus type 1 strain Mahoney (PV1/M) is known to elute to the culture medium during incubation at 37 degrees C, and only a fraction of the virions remaining cell-associated will successfully uncoat and contribute to the new replication cycle. We found that while the proportion of inoculum type 3 poliovirus strain Saukett (PV3/S) bound to GMK cells was of the same order as that of PV1/M, the bound PV3/S virions uncoated much less efficiently, as judged by velocity sedimentation analysis of virion disintegration. Rather, the majority of the cell-associated PV3/S viruses remained apparently unaffected for several hours within an unidentified intracellular compartment. Incubation of PV3/S with intestinal trypsin is known to result in selective cleavage of the capsid protein VP1 and striking antigenic changes. Trypsin treatment of stock PV3/S preparations did not affect the infectivity titre or modify single-cycle progeny virus yields significantly. However, the fate of the cell-bound inoculum virus was profoundly altered. Trypsin-treated PV3/S virions (PV3/S-Try) attached to GMK cells less tightly than the untreated PV3/S virus or PV1/M, and a relatively larger proportion of the cell-bound virus eluted to the medium during subsequent incubation at 36 degrees C. However, the fraction of virions remaining cell-associated rapidly disintegrated suggesting efficient uncoating. In accordance with these observations, one step growth curves of PV3/S-Try in all cell lines tested showed lowered eclipse phase titres compared to those obtained with the untreated PV3/S inocula. Similar effects were also demonstrated for type 3 poliovirus strain Sabin while trypsin-sensitive strains of the other two serotypes of poliovirus remained unaffected in this sense. The putative biological significance of the altered sorting of cell-bound PV3/S-Try virions is not known. It might be related to the observations that sensitivity of type 3 poliovirus strains to trypsin is conserved in spite of the fact that the target site of trypsin action is flanked by highly variable motives in an immunodominant antigenic site.
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PMID:Selective cleavage by trypsin of the capsid protein VP1 of type 3 poliovirus results in improved sorting of cell bound virions. 871 19

We exposed representatives of different enteroviruses to treatments imitating various in vivo environments that they face during infection. Short-term treatment in trypsin or human intestinal fluid regularly resulted in a cleavage of the capsid protein VP1, and in some cases of other capsid proteins as well. Infectivity of the virus preparations was usually not affected but there were two exceptions. Coxsackievirus A9 retained its infectivity as tested in RD cells but showed reduced infectivity in GMK cells, as reported previously. More strikingly, the titre of echovirus 22 was decreased by 2 logs. Overnight incubation in intestinal fluid affected the infectivity of all tested viruses, including polioviruses and coxsackievirus B4. Echovirus 22 and, to a lesser extent, coxsackievirus A9 were also partially inactivated by faecal suspension. After 2 h exposure to pH 2 at 37 degrees C all tested viruses retained their infectivity, but after 24 h all were inactivated. We conclude that the stability of enteroviruses exposed to various natural environments varies significantly, and that echovirus 22, no more classified in the genus Enterovirus, appears relatively more sensitive in body fluids.
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PMID:Variability in the integrity of human enteroviruses exposed to various simulated in vivo environments. 979 Aug 72