Only minimal amounts of poliomyelitis virus were formed by HeLa cells placed in a medium free from glucose and glutamine, even if the medium contained an otherwise full complement of essential and non-essential amino acids, purines, pyrimidines, NB4+, and serum protein. Conversely, within one log of the optimal yield of virus was formed by HeLa cells in a medium containing only glucose, glutamine, and salts, even if the cells had been starved in this medium for 12 hours prior to their inoculation.
The presence of glucose alone caused an average 170-fold increase in viral output beyond the amounts formed by the glucose- and glutamine-depleted cells. The addition of glutamine alone caused an average 2000-fold increase; and the addition of both increased the viral formation 40,000-fold. Qualitatively similar results were obtained with unstarved cells, not previously depleted of glucose and glutamine. It follows that only a small proportion of HeLa cells are capable of forming virus unless either glucose or glutamine, or both, are present in the medium.
The elaboration of virus was significantly delayed in media containing glucose but no glutamine.
The absence of glucose and glutamine did not prevent the fixation of poliomyelitis virus by the cell. When these compounds were added to previously depleted cells even 6 hours after inoculation, and after the excess free virus had been removed by washing and by the addition of specific antiserum, normal amounts of virus were formed despite the degenerative changes caused by the previous glucose and glutamine deprivation. Possible functions of glucose and glutamine in the elaboration of virus are discussed in the text.
Such factors other than glucose, glutamine, or salts (e.g. amino acids, purines, pyrimidines, vitamins, protein, or NH4+) as may be needed by HeLa cells for the propagation of poliomyelitis virus, need not be present in the medium and cannot be easily washed out of the cell. Even 12 hours' total deprivation of the cells in salt solution prior to inoculation only slightly decreased their virus-synthesizing capacity in a similarly deficient medium, provided only that adequate amounts of glucose and glutamine were retained.