GENETIC STABILITY OF ORAL POLIO VACCINE PREPARED ON PRIMARY MONKEY KIDNEY-CELLS OR VERO CELLS - EFFECTS OF PASSAGE IN CELL-CULTURE AND THE HUMAN GASTROINTESTINAL-TRACT

The genetic stability of the three Sabin oral poliovaccine (OPV) strai ns produced on either primary monkey kidney (VK) or Vero cell substrat es was compared in vivo and in vitro by measuring the rate at which th e bases most strongly associated with attenuation and reversion to neu rovirulence (positions 480, 481, and 472 in the 5' non-coding region o f Sabin 1, 2 and 3 respectively, and 2034 in VP3 of Sabin 3) reverted during passage of the vaccine strains in the gastrointestinal tract of primary vaccinees and in cell culture. For the in vivo study, the pol iovirus excretion patterns of 21 infants receiving OPV produced on eit her VK or Vero cells were followed for 21 days. No significant differe nces in either the frequency of excretion or the rate of reversion wer e observed between the two vaccine groups. The rate of accumulation of revertants during passage in vitro was compared for the three Sabin s trains passaged 10 times in either VK or Vero cells. For types 1 and 3 , revertants accumulated faster upon passage through VK cells compared with passage through Vero cells. Type 2 appeared to be stable as no r evertants were detected in either cell type. Results of this study sug gest that the use of Vero as opposed to VK cells as substrate for the manufacture of OPV does not negatively influence the generic stability of-the three Sabin OPV strains in vivo or in vitro. (C) 1998 Elsevier Science Ltd. All rights reserved.