Table 1.
Vaccine groups, morbidity, mortality and mean viral shedding from the oropharyngeal (OP) and cloacal (CL) routes.
Fig 1.
Mean antibody Hemagglutination Inhibition titers of vaccinated chickens 25 days post vaccination (pre-challenge).
Titers were determined against three different antigens, TK/IN/22 (A), Viet/04 (B), and WS/Mongolia/05 (C). Titers of eight or lower are regarded as negative and sera negative by HI assay were assigned an imputed titer of four, which is 50% of the cut off value. P values are represented as * for p <0.05, and *** for p<0.001.
Fig 2.
Survival curve of chickens vaccinated with sham vaccine, COBRA-HVT, or 2.2-HVT after challenge with TK/IN/22 HPAI virus.
Fig 3.
Viral shedding titer equivalents from oropharyngeal and cloacal swabs collected from white leghorn chickens (A and B) or broiler chickens (C and D) 2-, 4- and 7-days post challenge (DPC). Titers were measured using quantitative rRT-PCR and converted into log10 50% egg infectious doses (EID50) per ml titer equivalents using the standard curve with RNA from quantified virus. Post-mortem shed titer data from sham vaccinated chickens that were dead or euthanized on 1DPC are merged with 2DPC and shed data from one WL chicken in the 2.2-HVT group that was euthanized on 6DPC is merged with 7DPC data of the same group. Columns for the sham vaccinated birds are not shown for 4 and 7 days because there were no birds left in these groups at those time points. P values are represented as * for p <0.05, and **** for p value <0.0001.
Fig 4.
Antibody to the N1 NA in post-challenge sera of chickens, measured by percent inhibition of neuraminidase activity by enzyme linked lectin assay-neuraminidase inhibition.
Post-challenge sera were collected 7-, 10-, and 14-days post challenge (DPC). (A) White leghorns with serum at a 1:20 dilution; (B) White leghorns with serum at a 1:40 dilution; (C) Broilers with serum at a 1:20 dilution; (D) Broilers with serum at a 1:40 dilution. Horizontal dotted lines indicate the cut-off determined by adding three standard deviations to the mean NI activity of pre-challenge sera from each group. Solid horizontal lines in each group indicate the median.
Table 2.
Antibody to the N1 NA and NP proteins in serum collected at 7-, 10- and 14-days post challenge (DPC) from chickens vaccinated with rHVT H5 avian influenza vaccines determined by ELLA-NI (serum 1:20 and 1:40 yielded the same results) and ELISA.