Table 2. Cross-strain influenza A(H3N2) antibody responses measured by HI assay.* .
| GROUP Yam/Vic: 2008–09/2010–11 TIV Sequence | Initiating antigen | Boosting antigen | |||
| Test Antigen | Brisbane-like | Brisbane-like | Perth | Perth | |
| Brisbane-like | Pre- vaccination | Post 2008–09 TIV 1a | Post 2008–09 TIV 2b | Post 2010–11 TIV 1a | Post 2010–11 TIV 2a |
| GMT (95%CI) | 5.0 | 32.5 (25.6–41.3) | 130 (102.3–165.1) | 1194.3 (729.4–1955.5) | 1114.3 (667.7–1859.6) |
| GMTR† | 6.50 | 26.0 | 9.19 | 0.93 | |
| % titre ≥40 (95%CI) | 0 | 70 (35–100) | 100 | 100 | 100 |
| Perth | |||||
| GMT (95%CI) | 5.0 | 5.0 | 6.2 (4.4–8.6) | 557.2 (302.9–1024.9) | 519.8 (324.8–832.1) |
| GMTR† | 1 | 1.24 | 89.87 | 0.93 | |
| % titre ≥40 (95%CI) | 0 | 0 | 0 | 100 | 100 |
| GROUP Vic/Yam: 2010–11/2008–09 TIV Sequence | Initiating antigen | Boosting antigen | |||
| Test antigen | Perth | Perth | Brisbane-like | Brisbane-like | |
| Brisbane-like | Pre- vaccination | Post 2010–11 TIV 1 a | Post 2010–11 TIV 2 b | Post 2008–09 TIV 1 a | Post 2008–09 TIV 2 a |
| GMT (95%CI) | 5.0 | 5.0 | 6.2 (4.8–7.8) | 343 (189.4–621) | 452.5 (296.9–689.7) |
| GMTR† | 1.00 | 1.24 | 55.32 | 1.32 | |
| % titre ≥40 (95%CI) | 0 | 0 | 0 | 100 | 100 |
| Perth | |||||
| GMT (95%CI) | 5.0 | 11.5 (6.5–20.2) | 183.8 (134.3–251.5) | 787.9 (523.8–1185.2) | 844.5 (597.1–1194.4) |
| GMTR† | 2.3 | 36.76 | 4.29 | 1.07 | |
| % titre ≥40 (95%CI) | 0 | 20 (0 – 50) | 100 | 100 | 100 |
HI = hemagglutination inhibition; TIV = trivalent inactivated influenza vaccine. Note that undetectable titres <10 were assigned a value of 5.
*
Unit of analysis pooled sera from 5 mice, thus 10 pools from 50 mice were available for this experiment.
a
Measured two weeks after specified TIV dose;
b
Measured two months after specified TIV dose.
†
Compared to pre-immunization for priming antigens; compared to immediately preceding titre for boosting antigens.
Brisbane-like = A/Uruguay/716/2007(NYMC 175C)(H3N2) considered antigenically equivalent to the WHO recommended A/Brisbane/10/2007(H3N2) component of the 2008–09 northern hemisphere TIV.
Perth = A/Perth/16/2009(H3N2)-like, component of the northern hemisphere 2010–11 TIV.