TABLE 1

Effects of the ΔPA-X FS mutation on HA yield of CVVs grown in eggs

Lineage and subtypeStrainNo. of independent rescuesHA titeraRelative HA titerbRelative HA1 yieldbNo. of expts.
6:2 virus6:2 FS virusTotalSmall scaleLarge scale
Human pdm09
    H1N1A/California/07/20092106 ± 86.6249 ± 1092.65 ± 2.161.90 ± 1.07c743
    A/California/07/2009 chimeric HA (NIBRG-119)11.54 ± 0.430211
A/England/195/200915.71 ± 0.71020.1 ± 9.923.79 ± 2.212.40 ± 0.370211
Human pdm1968
    H3N2A/Udorn/307/7222200 ± 9292100 ± 7201.26 ± 0.4701.35 ± 0.360532
A/Hong Kong/1/681801 ± 117843 ± 1401.05 ± 0.061.22 ± 0.390321
Avian
    H7N3A/mallard/Netherlands/12/2000 (NIBRG-60)233.5 ± 29.145.0 ± 36.91.34 ± 0.1801.55 ± 0.140532
    H5N1A/turkey/Turkey/1/2005/1/2005 (NIBRG-23)247.1 ± 27.348.8 ± 23.21.13 ± 0.2301.10 ± 0.300532
    H1N1A/mallard/Netherlands/10/992123 ± 59.0128 ± 37.01.22 ± 0.3701.13 ± 0.360541
    H9N2A/chicken/Pakistan/UDL-01/20082302 ± 364312 ± 2640.920 ± 0.3001.01 ± 0.180422
  • a Average HA titers of eggs incubated at 35°C. Values are means ± standard deviations.

  • b Ratio of the average HA titer or HA1 yield of FS (Δ PA-X) viruses to values for their WT counterparts (from eggs incubated at 35°C or 37.5°C). Values are means ± standard deviations.

  • c An outlier from one experiment was ignored in calculation of the average.