TABLE 4.

Intracellular virus neutralization by IgA antibodies to F, N, and H and by antibody combinationsa

IgA MAb (μg/ml)Apical supernatantCell lysate
Virus titer (10−3 PFU/ ml)% Reduction of virusbVirus titer (10−5 PFU/ ml)% Reduction of virusb
Anti-H (100)0.48 ± 0.04c980.93 ± 0.16c84
Anti-F (100)18.9 ± 1.80d262.52 ± 0.28c57e
Anti-N (100)16.8 ± 2.40d342.25 ± 0.26c62e
Anti-H (50)6.12 ± 0.69c761.70 ± 0.39c71
Anti-H (33)8.06 ± 0.52c681.96 ± 0.46c66
Anti-H (50) + anti-F (50)2.05 ± 0.79c922.13 ± 0.51c64e
Anti-H (50) + anti-N (50)1.67 ± 0.53c932.28 ± 0.76c61e
Anti-F (50) + anti-N (50)25.2 ± 2.40d13.91 ± 0.65c33e
Anti-H (33) + anti-F (33) + anti-N (33)3.29 ± 0.77c872.33 ± 0.54c60e
Irrelevant (100)25.5 ± 4.9005.81 ± 1.021
None25.5 ± 5.1005.85 ± 0.280
  • a Experiments were repeated on at least three occasions with similar results. Results of a representative experiment are shown. Data are mean ± standard deviations (n = 3).

  • b Compared to no-antibody control.

  • c Mean virus titers were significantly lower (P < 0.01) than those from cells exposed to no antibody.

  • d Mean virus titers were not significantly lower (P > 0.05) than those from cells exposed to no antibody.

  • e A significantly smaller percent reduction (P < 0.04) than that with anti-H alone at 100 μg/ml.