| Popis: |
A urea-resistant mutant of type 1, LSc poliovirus, called LSc-U r , always produced about 30% of the progeny and 50% of the viral-specific RNA in infected cells as compared to its parent virus. LSc-U r virus was found to attach normally at low multiplicities of infection (m.o.i.) but exhibited autointerference at higher m.o.i. For example, at an m.o.i. of 10, less than 25% of the added virions was cell associated after 90 min. Neither parental LSc nor Mahoney poliovirus exhibited unusual attachment kinetics under comparable conditions. In addition, LSc-U r (m.o.i. = 10) interfered markedly with the attachment of Mahoney poliovirus. These findings were interpreted as resulting from a high particle/PFU ratio for the LSc-U r virus. LSc-U r virus partially purified by differential and sucrose gradient centrifugations still exhibited attachment autointerference at high m.o.i. in contrast to virus purified by CsCl banding which showed normal attachment and a much reduced ability to interfere with the attachment of other polioviruses. These results provide circumstantial evidence that LSc-U r virus preparations contain virion-like particles ( s 20,w of 120–150 S) which compete with the attachment of virions to cell receptors and which are degraded by high concentrations of CsCl. |
