Table 3.
HI titers induced by passive immunization, vaccination, and challenge with Mexican lineage H5N2 LPAI
| Group | Condition/immunization | Mean serum HI antibody titer (Log2)a | ||||
|---|---|---|---|---|---|---|
| Days from the start of the experiment | ||||||
| 1 (Prime) | 10 (Boost) | 21 | 35 (Challenge) | 50 | ||
| 1 | Naïve | ndb | nd | nd | <e | 5·8 (10/10) |
| 2 | Vaccine control | nd | nd | 8·9 (9/9) | 9·4 (9/9) | 10·3 (9/9) |
| 3 | Laboratory antiserum, neat | 5·0 (6/9)c | nd | 5·3 (5/10) | 7·1 (10/10) | 9·1 (10/10) |
| 4 | Laboratory antiserum, 1:2 dilution | 4·2 (7/11) | < | 6·0 (6/11) | 7·5 (10/11) | 8·5 (11/11) |
| 5 | Laboratory antiserum, 1:2 dilution | 3·9 (7/11) | < | 5·9 (7/11) | 8·4 (11/11) | 10·0 (11/11) |
| 6 | Field antiserum, neat | 3·6 (7/10) | nd | 5·3 (3/10) | 6·8 (8/10) | 8·4 10/10) |
| 7 | Field antiserum, 1:2 dilution | 2·8 (5/10)d | < | 4·9 (7/10) | 7·7 (10/10) | 9·6 (10/10) |
| 8 | Field antiserum, 1:2 dilution | 3·3 (6/11) | < | 5·4 (10/11) | 8·7 (11/11) | 10·1 (11/11) |
a
Expressed as the log2 of the reciprocal of the highest dilution that inhibited 4 hemagglutinating units of homologous virus. Results are presented as the arithmetic mean of positive sera (HI titer ≥1:10 dilution). The number of positive sera/total is indicated in parenthesis.
b
Not determined.
c
1 bird found dead from natural causes prior to study commencement.
d
1 bird was removed from the study after being transferred to the wrong area of biocontainment.
e
< Indicates all chickens at this time point had HI titers below the cutoff value.