Pathologic and Immunohistochemical Studies of Newcastle Disease (ND) in Broiler Chickens Vaccinated with ND: Severe Nonpurulent Encephalitis and Necrotizing Pancreatitis

Abstract

Abstract. Twenty-five 22-to 46-day-old broilers with Newcastle disease (ND) were investigated pathologically and immunohistochemically in order to evaluate the mechanism of ND outbreak in vaccinated broilers. The broilers were vaccinated with ND live vaccine via drinking water. Clinical signs were neurologic and respiratory in nature. Macroscopically, bursal atrophy, white spots on the pancreas, and discoloration and enlargement of kidneys and spleen were observed in the broilers. Histologically, perivascular cuffing, neuronal degeneration and necrosis, and glial proliferation were present in the cerebrum, cerebellum, and medulla oblongata. There was extensive rarefaction and malacia in the parenchyma of severely affected brains. There were extensive degeneration, necrosis, and depletion of acinar cells in the pancreas. There was proliferation of macrophages in the lungs with congestion, tubulointerstitial nephritis, hepatocytic necrosis with thrombi in the sinusoids, and lymphocytic depletion in the cloacal bursa. Immunohistochemically, ND virus antigens were detected in the lesions. ND virus isolated from the present cases did not cause encephalitis or pancreatitis in specific-pathogenfree chickens, but it induced mortality with hepatocytic sinusoidal thrombi, splenic necrosis, lymphoid necrosis and depletion, and conjunctival hemorrhage. Severe nonpurulent encephalitis with extensive rarefaction and malacia, and necrotizing pancreatitis in the present case may suggest a close possibly causal relation with vaccination.

Use of immunohistochemistry (IHC) in the detection of Newcastle disease virus (NDV) in experimentally and naturally infected birds

“…The results of this study were partially similar to those presented elsewhere (Nakamura et al, 2008),with the use of immunohistochemistry after an outbreak in the detection of NDV antigens of the disease in different samples of tissues from 25 broilers that had been previously vaccinated.…”

“…This finding demonstrated greater infectivity to other organs when infection was caused by virulent strains, as well as the presence of clinical signs. Finding of the viral antigen is directly related to the lesions and clinical signs presented by the birds (Nakamura et al, 2008). Because of this, as the trachea is the primary site of replication of NDV no matter the strain involved, it is the main tissue used in IHC (Alexander, 2003).…”

“…Therefore, a reliable, safe and easy-to-perform method for the diagnosis should be considered, as the quicker the diagnosis, the more efficient the disease control measures to be put in place, preventing greater losses and the spread of the disease (Kho et al, 2000). Studies involving the use of tissue samples are extremely important for better understanding of the distribution of the viral agent in infected organs, the protection ability of a vaccine, or the pathogenicity of a strain (Barbezange and Jestin, 2005;Nakamura et al, 2008Nakamura et al, , 2014Ezema et al, 2009;Cattoli et al, 2011).…”

“…These tests are cumbersome, labor-intensive, inhumane and, sometimes, inconclusive (Tiwari et al, 2004). Virological, pathologic and immunohistochemical analysis of chickens with ND in field conditions have been useful in the investigation of the mechanisms of ND outbreaks in vaccinated chickens (Nakamura et al, 2008;Bwala et al, 2012). IHC is performed on formalin-fixed, paraffinembedded tissues and, in many cases, the viral antigen can be detected in autholyzed tissues.…”

“…As ND does not cause pathognomonic histopathological lesions, immunological techniques, such as IHC have become important tools in diagnosis and may, therefore, detect the agent in tissue samples (Ojok and Brown, 1996;Oldoni et al, 2005;Piacenti et al, 2006;Wakamatsu et al, 2006;Nakamura et al, 2008). Besides, this technique may replace virus isolation, or even molecular tests, in places where there are no laboratories of adequate biosafety level for this procedure (Brown et al, 1999a, b;Wakamatsu et al, 2006).…”