The effect of velogenic Newcastle disease virus (vNDV) on the immune responses and serum proteins was investigated in six-week-old ducks and chickens. Results showed that weight loss was markedly significant (p < 0.05) from days 3 - 21 (PI) in chickens and mild (p < 0.05) on days 3 and 15 PI in ducks. The antibody response obtained showed significant (p < 0.05) increase in infected chickens (IC) than those of the infected ducks (ID). While the total serum protein and serum globulin increased significantly (p < 0.05) in IC on days 7 and 14 PI, they decreased significantly (p < 0.05) in ID only on day 21 PI. The immune responses and serum protein values in this experiment X-ray showed less susceptibility of ducks when compared with the chickens. This may be related to marked anorexia and severe dehydration observed in the latter consequent upon serum concentration. Ducks could be maintaining the endemicity of Newcastle disease (ND) as reservoir host.
Proteins are the most abundant compound in the serum comprising amino-acid building blocks and are in turn, building blocks for cells and tissues [
One hundred and seventy day old birds hatched the same day were obtained comprising 70 ducklings from poultry section of National Veterinary Research Institute NVRI Vom and 100 cockerel chicks from Zartech Hatchery. Brooding was done separately for the chicks and ducklings on deep litters under the same environmental conditions. The cockerels received IBD vaccine by intraocular route at days 10 and 24 post hatch (PH). Chicks’ mash was given ad libitum to the birds from day old to 8 weeks PH. Growers’ mash was given ad libitum also from 9 weeks PH until the end of the experiment. Water was allowed free choice.
The VNDV strain, (Kudu-113) was acquired and used in the challenge experiment.
At six weeks of age the chicks and ducklings were each randomly assigned into two groups of infected chicks (IC), uninfected chicks (UC) and infected ducks (ID), uninfected ducks (UD). The inoculum was reconstituted to give embryo lethal dose (ELD50) titre of 106.36 per ml. The chicks and ducks in groups IC and ID were inoculated intramuscularly (IM) with 0.2 ml of the inoculum (infected groups). The chicks and ducks in groups UC and UD received 0.2 ml of phosphate buffered solution IM (control groups). The infected and control groups were housed at different locations and maintained on deep litter system.
At day 3 PI, 10 birds from each group were randomly selected, marked, weighed and the weight recorded as live body weight (LBW) of each group. The marked birds were re-weighed at days 6, 9, 12, 15 and 21 PI.
Blood samples (3ml/bird) were collected from 10 birds in each group on days 0, 7, 14, and 21 PI through the wing vein, using sterile syringe. The sample bottles were stoppered, laid on near horizontal position, and allowed to clot. The serum samples were harvested into 2 ml vials. The duck sera were inactivated at 56˚C in water bath for 30 minutes and with the chicken sera, use in the serological analysis.
Two ml of ND sero-negative chicken blood was collected from adult bird in a test tube containing EDTA and washed according to standard procedure. Using the formula CV = RxV/O, where CV = calculated volume (ml) of washed RBC, R = required % of RBC (0.5 %), V = volume (ml) of PBS intended to be used in the dilution and O = original PCV (%) of the RBC after washing, 0.5% of the washed chicken RBC was prepared [
The standard HA technique as described by Beard, [
The standard HI technique as described by Beard, [
At days 0, 7, 14 and 21 PI, 10 birds from each group were randomly selected and at least 3 ml blood samples collected through the wing vein, into plain test tubes and serum samples harvested from the clotted blood into 2 ml vials and stored at –40˚C for serum protein studies.
The TSP was determined using direct Biuret method. Biuret reagent containing NaOH, potassium iodide, copper (II) sulphate and sodium—potassium tartarate and Standard containing aqueous solution of protein, equivalent to 5 g/dL (50 g/L) were used [
The total proteins were calculated as follows: Total protein (g/dL) = absorbance of sample × 5/absorbance of standard.
The SAL was determined using bromocresol green method. Bromocresol green reagent containing bromocresol green, succinate buffer (pH 4.2), surfactants, preservatives and stabilizers, and standard containing aqueous solution equivalent to 5 g/dL (50 g/L) of albumin were used [
The serum albumin was calculated as follows:
The globulin fraction was calculated as the difference between total serum proteins and serum albumin level; SGF (g/dL) = TSP – SAL.
The LBW, HI and serum protein values between and within groups were subjected to statistical analysis using independent sample t-test and the level of significance was determined and accepted at p ≤ 0.05 for all the results using statistical product for service and solution (SPSS) version 16.0 computer software. The mean ± standard error of mean (SEM) of the results obtained in the experiment were calculated and presented in tables, graphs and charts.
The result of live body weights of both species are shown on
The PI HI values were determined and the results are shown in
. Mean live body weight (g) ± SEM of chickens and ducks.
Days PI | Infected chickens | Control chickens | Infected ducks | Control ducks |
---|---|---|---|---|
0 | 680.00 ± 23.81 | 680 ± 23.805 | 314.00 ± 9.91 | 314.00 ± 09.91 |
3 | 632.00 ± 18.61* | 746.00 ± 17.59 | 283.00 ± 12.65* | 349.50 ± 19.30 |
6 | 679.00 ± 28.61 | 745.00 ± 20.12 | 386.00 ± 24.13 | 356.00 ± 16.61 |
9 | 763.00 ± 51.45 | 835.00 ± 23.63 | 360.00 ± 20.98 | 384.50 ± 16.34 |
12 | 763.00 ± 46.60* | 996.00 ± 31.70 | 363.00 ± 19.22 | 386.00 ± 19.56 |
15 | 795.00 ± 47.40* | 1030.00 ± 41.95 | 358.00 ± 27.36* | 414.50 ± 20.42 |
21 | 867.00 ± 38.73* | 1044.00 ± 34.13 | 450.00 ± 19.72 | 448.50 ± 20.17 |
*Means values significantly different at p < 0.05 along the same row.
. Hemagglutination inhibition in chickens and ducks.
Geometric mean titre ± SEM | ||||
---|---|---|---|---|
Days | IC | UC | ID | UD |
D0 PI | 000.00 ± 00.00 | 000.00 ± 00.00 | 00.00 ± 0.00 | 000.00 ± 00.00 |
D7 PI | 105.60 ± 20.27 | 000.00 ± 00.00 | 22.40 ± 4.89* | 000.00 ± 00.00 |
D14 PI | 537.60 ± 59.73 | 000.00 ± 00.00 | 32.00 ± 0.00* | 000.00 ± 00.00 |
D21 PI | 119.20 ± 17.64 | 000.00 ± 00.00 | 36.80 ± 6.33* | 000.00 ± 00.00 |
*Means values significantly different at p < 0.05.
(105.60 ± 20.27 and 22.40 ± 4.89), 14—(537.60 ± 59.73 and 32.00 ± 0.00), and 21—(119.20 ± 17.64 and 36.80 ± 6.33), PI respectively. Control chickens and UD had zero titre throughout the period of the experiment.
The results of the serum proteins are shown in
The results of the SGF are shown in
The results of the SAL are shown in
Since maternal antibody could be detected in chickens up to 3 weeks of age [
. Total serum proteins ± SEM (g/dL × 10).
Days | IC | UC | ID | UD |
---|---|---|---|---|
0 | 4.09 ± 0.17 | 4.09 ± 0.17 | 5.25 ± 1.66 | 5.25 ± 1.66 |
7 | 6.00 ± 0.14* | 5.34 ± 0.11 | 5.44 ± 0.12 | 5.76 ± 0.09 |
14 | 3.13 ± 0.12* | 2.55 ± 0.40 | 3.81 ± 0.25 | 3.37 ± 0.13 |
21 | 2.55 ± 0.09* | 3.61 ± 0.14 | 3.13 ± 0.05* | 4.35 ± 0.13 |
*Means values significantly different at p < 0.05.
. Serum globulin proteins ± SEM (g/dL × 10).
Days | IC | UC | ID | UD |
---|---|---|---|---|
0 | 2.63 ± 0.19 | 2.63 ± 0.19 | 3.44 ± 0.11 | 3.44 ± 0.11 |
7 | 3.96 ± 0.27* | 3.29 ± 0.21 | 4.10 ± 0.99 | 3.93 ± 0.17 |
14 | 1.63 ± 0.20* | 1.13 ± 0.05 | 2.41 ± 0.24 | 1.80 ± 0.22 |
21 | 1.03 ± 0.12* | 1.75 ± 0.21 | 1.42 ± 0.05* | 2.61 ± 0.19 |
*Means values significantly different at p < 0.05.
. Serum albumin proteins ± SEM (g/dL × 10).
Days | IC | UC | ID | UD |
---|---|---|---|---|
0 | 1.46 ± 0.10 | 1.46 ± 0.10 | 1.81 ± 0.10 | 1.81 ± 0.10 |
7 | 2.04 ± 0.16 | 2.03 ± 0.17 | 1.30 ± 0.07* | 1.81 ± 0.10 |
14 | 1.50 ± 0.11 | 1.42 ± 0.56 | 1.40 ± 0.06 | 1.59 ± 0.08 |
21 | 1.49 ± 0.06 | 1.87 ± 0.19 | 1.68 ± 0.29 | 1.74 ± 0.12 |
*Means values significantly different at p < 0.05.
the HI test. One of the mechanisms by which antibodies fight against pathogens is neutralization, particularly viruses [
The serum proteins elevation was more in chickens that presented higher antibody response and this may be associated with hyper-globulinemia due to sero-conversion to immunoglobulin [