Yield increases in intact influenza vaccine virus from chicken allantoic fluid through isolation from insoluble allantoic debris

A yield enhancement technology for use in influenza vaccine manufacturing has been developed to maximize the recovery of influenza virus from allantoic fluid of virus-infected chick embryos; the standard raw material for influenza vaccine. Virus associated with amorphous debris in the allantoic fluid can be dissociated from the debris and recovered, thereby increasing viral yield. Dissociation can be achieved by subjecting the virus–debris complex to conditions of increased ionic strength at defined pH. Multifold increases in viral yield per ml of allantoic fluid were observed. The degree of yield enhancement is strain-specific, however, increases were observed in all type A and type B influenza strains tested. The heightened influenza virus recoveries can facilitate rapid vaccine manufacture, with increased numbers of doses produced, and may become essential at a time of influenza pandemic.