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Table 3 Matrix indicating the number and percentage of log antibody titres obtained in two HI tests after experimental infection of ducks with H5N1

From: Comparison of serological assays for detecting antibodies in ducks exposed to H5 subtype avian influenza virus

  HI-HRBC log titres
HI CRBC log titres <2 2 3 4 5 6 7 8 N Total (%)
<2 16 0 0 1 0 0 0 15 (28.3)  
2 0 0 2 0 1 0 0 0 4 (5.0)
3 0 2 3 0 1 0 0 0 6 (10.0)
4 0 0 1 0 0 0 0 0 1 (1.7)
5 0 0 0 1 2 0 0 0 3 (5.0)
6 0 0 0 0 3 7 4 0 14 (23.3)
7 0 0 0 0 1 5 4 0 10 (16.7)
8 0 0 0 0 0 0 4 2 6 (10.0)
N Total (%) 16 (26.7) 2 (3.3) 6 (10.0) 1 (1.7) 9 (15.0) 12 (20.0) 12 (20.0) 2 (3.3) 60
  1. Ten ducks were inoculated with H5N1 virus and were sampled before inoculation and at 8, 15, 22, 29 and 34 days post inoculation. HI titers are expressed as the log2 value of the reciprocal of the highest dilution causing inhibition of haemagglutination. The lowest detectable antibody titre was 2 log2; thus, any sera with titres below this were classified as<2 log2. HI titres of =4 log2 were classified as positive. Abbreviations: HI-CRBC (Haemagglutination inhibition test using chicken red blood cells), HI-HRBC (Haemagglutination inhibition test using horse red blood cells), N (number).