Table 2.
Results of protection from immunized chickens after challenge.
| Groups | Vaccine | Number of positive/total | Protection ratio (%) |
|---|---|---|---|
| 1 | GST-sM2 | 0/15 | 0 |
| 2 | GST-C3d-L1-C3d-L2-sM2 | 3/15 | 20 |
| 3 | pcDNA-sM2 | 1/15 | 6.7 |
| 4 | pcDNA-C3d-L1-C3d-L2-sM2 | 2/15 | 13.3 |
| 5 | GST-sM2+IFA | 4/15 | 26.7 |
Chickens were immunized thrice with GST-sM2, GST-C3d-L1-C3d-L2-sM2, pcDNA-sM2, pcDNA-C3d-L1-C3d-L2-sM2 and GST-sM2+IFA, respectively. Then all the Chickens were challenged with 5× 106.5 EID50 of the A/chicken/Bei Jing/WD9/98 (H9N2) virus. On the indicated days, chickens were euthanatized, lung samples were collected and subsequently homogenized and inoculated in SPF chicken embryos for the presence of infectious virus. Virus isolation was operated as described in the Materials and Methods. The chicken was considered to be protected whichever HA test was negative in two virus isolations. The protections from immunized mice on day 5 p.i. are shown.