Molecular and pathological investigation of a natural outbreak of Newcastle disease caused by genotype XVII in White Leghorn chickens

Figures & data

Figure 1. (a) Carcasses from the outbreaks showing high mortality. (b) Conjunctival and corneal congestion with comb and wattle congestion. (c) Greenish-yellow faecal pasting of the vent in carcasses. (d) Diffuse pancreatic necrosis. (e) Proventriculo-ventricular junction ecchymotic haemorrhages. (f) Testicular vascular congestion, severe. (g) Ovarian follicular congestion with ecchymotic haemorrhages and egg yolk peritonitis.

Table 1. Chronological events of the outbreak, clinical signs, and mortality.

Day	Clinical signs	Initial flock size	Number dead	Flock size after	Mortality rate
0	Generalised weakness, inappetence and greenish diarrhoea	1229	0	1229	0
1	Greenish diarrhoea, high mortality	1229	102	1127	8.3%
2	Lethargy, high mortality	1127	164	963	14.5%
3	Lethargy, high mortality	963	220	743	22.8%
4	Conjunctivitis, lethargy, high mortality	743	98	645	13.2%
5	Conjunctivitis, lethargy, high mortality	645	42	603	6.5%

Table 2. Distribution and intensity of gross and histological lesions with immunohistochemical (IHC) staining for NDV nucleoprotein.

System	Gross lesion	Histopathology	IHC
Respiratory	Pulmonary congestion/airsacculitis (54/60)	Pulmonary vascular congestion (11/15) and airsacculitis (8/15)	Severe intracytoplasmic staining in airsac cells (8/15)
Digestive	Fatty liver (54/60), obesity (52/60), peritoneal and subserosal fat petechiae haemorrhages, proventricular erosion (30/60)/ mucus hypersecretion (24/60), proventriculo-ventricular junction ecchymotic haemorrhages/ulceration (36/60), enteritis/catarrhal (54/60), ascites (9/60), egg yolk peritonitis (48/60), yellowish-white to greenish-white faecal pasting of the vent (42/60), diffuse pancreatic necrosis, multifocal, irregular (45/60), pancreatitis (15/60)	Macro and micro vesicular fatty infiltration, proventricular epithelial cell necrosis and haemorrhage with mucosal-associated lymphoid tissue (MALT) hyperplasia, severe propria necrosis, duodenal and ileal cryptic necrosis, destruction and mononuclear cellular infiltration, intestinal wall ganglioneuritis (13/15) with lymphoplasmacytic infiltration, enteritis with severe villi destruction and infiltration by mainly lymphocytes, ilea MALT necrosis and depletion, diffuse pancreatic acinar cell necrosis (15/15), patchy multifocal degenerate acinar cells and pancreatitis with macrophage and lymphocyte infiltration.	Moderate detection of diffuse ND viral nucleoprotein in cryptic enterocytes, and in laminar propria, hepatocytes and acinar cells of the pancreas (15/15)
Nervous	Meningeal congestion 30/60	Cerebral neurons with central chromatolysis and pyknosis, some neurons with small, 8 µm in diameter, 1–3 eosinophilic intranuclear inclusions (8/15); meninges expanded with a large amount of lymphoplasmacytic cellular infiltrates; cerebral vascular congestion, lymphocytic perivascular cuffing in cerebrum (6/15) and gliosis	Detection of ND viral nucleoprotein in meningeal epithelial cells (12/15)
Reproductive	Atretic ovarian follicles (6/60), follicular (12/60), and testicular ecchymotic haemorrhages (6/60)	NA	NA
Immune	Moderate splenomegaly (23/60)	Severe splenic necrosis and lymphoid follicular loss (14/15)
Integumentary	Pale (18/60)/congested comb and wattles (21/60).	NA	NA
Special senses	Conjunctival and corneal congestion (15/60)	NA	NA

Figure 2. (a) Meningoencephalitis with severe lymphocytic cellular infiltration. (b) Encephalitis with formation of perivascular lymphocytic cuffs. (c) Pancreatic acinar cells are diffusely necrotic with obliteration of islands of Langerhans. (d) Splenic lymphoid follicular necrosis. (e) Enteritis, with severe lymphocytic cellular infiltration. (f) Ganglioneuritis with lymphoplasmacytic infiltration in the intestinal wall, H &E.

Figure 3. (a) Airsac, high intranuclear and intracytoplasmic staining in cells. (b) Meningeal epithelial lining cells intranuclear and intracytoplasmic staining. (c) Cerebral and meningeal epithelial lining cells intranuclear and intracytoplasmic staining, moderate. (d) Pancreas, severe intranuclear and intracytoplasmic staining in acinar cells X100, IHC.

Figure 4. Phylogenetic tree of Newcastle disease virus based on the complete fusion gene. The tree was constructed using Maximum Likelihood in MEGA 6 with 500 boostrap replicates to assign confidence to the groupings. The tree with the highest log likelihood (−9569.8326) is shown. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The isolate in this study is highlighted in red. Colour online.