LaSota vaccination may not protect against the lesions of velogenic newcastle disease in chickens

Abstract

Two groups of six weeks old cockerels comprising 40 immunized and 40 non-immunized birds were inoculated intramuscularly with VGF-1, which is a local Nigerian strain of velogenic Newcastle disease virus (VNDV). Immunized birds did not show any clinical signs except significant loss (p < 0.05) in body weight on days 5 and 20 post inoculation (PI). But the non-immunized birds showed clinical signs of disease characterized by anorexia and drowsiness from day 2 PI. These were followed on day 3 PI by depression, diarrhoea, opisthotonus, weight loss (p < 0.05) and high mortalities (96.9%). Both the immunized and non-immunized groups showed severe atrophy of the bursa, spleen and thymus. Histopathological section of these lymphoid organs showed necrosis and depletion of lymphocytes. Both the gross and microscopic lesions were more severe in the non-immunized birds. Marked ballooning degeneration was observed in the bursal follicles of the non-immunized birds. This lesion has not been described earlier for any other disease and could be diagnostic for VND. Our results also showed that VND can cause marked atrophy of the lymphoid organs, which may lead to immunosupression without the characteristic signs of Newcastle disease (ND) in vaccinated chickens. This no doubt emphasizes the limitation of vaccination as a biosecurity measure in poultry industry.

Comparative Evaluation of the Effects of Velogenic Newcastle Disease Virus Infection on the Hematology of Ducks and Chickens

“…The lymphopenia recorded in chicken may be associated with depletion of lymphocytes in the bursa of Fabricus, spleen and thymus as reported by Ezema et al [24]. Monocytopenia is a form of leukopenia associated with a deficiency of monocytes and which may be caused by acute infections, and other numerous disease syndromes [25].…”

“…Lymphopenia is common in acute inflammatory responses, because inflammatory mediators stimulate the diapedetic migration of heterophils and lymphocytes from the blood and lymphoid tissues to the points of inflammation where they are eventually destroyed [28]. This may account for the immunosuppression previously reported in vND in chickens [24]. The monocytosis and then monocytopenia in the infected chicken and monocytosis in duck may be related to the transit period of monocytes from bone marrow to the tissues as macrophages [27] and the variations between the 2 species may be related to the extent of tissue damage [27].…”

In vitro characterization of the antiviral activity of fucoidan from Cladosiphon okamuranus against Newcastle Disease Virus

“…Vaccination is practiced widely, and it remains the recommended method for prevention. Although vaccination using live and killed vaccines is widely used as a management practice, the velogenic strains are endemic in the commercial poultry of many countries [15,16]. This represents a major problem for the poultry industry and therefore requires further measures to prevent and control this disease.…”

Selective Hematological, Biochemical and Pathological Alterations of Newcastle Virus in Naturally Infected and Vaccinated Broilers in Damietta Governorate of Egypt

“…Lymphocytopenia is common in acute inflammatory responses, because inflammatory mediators stimulate the diapedetic migration of heterophils and lymphocytes from the blood and lymphoid tissues to the points of inflammation where they are eventually destroyed (Ng et al, 2005). This may account for the immunosuppression previously reported in NDV in chickens (Ezema et al, 2009 fig. (2) general, the histological scores obtained for each organ were significantly higher in the non-vaccinated group compared to the vaccinated group (P<0.05) (Figs 3,4 and Tables 4,5), ND-infected broilers of group (II) showed a significant (P<0.05) decrease in serum total proteins, albumin and A/G ratio with nonsignificant changes in serum total globulins beside an increases in serum concentrations of uric acid and creatinine (P<0.05), this supported by histopathologial findings in the current work revealed that ND-infected non-vaccinated chickens (gp.II) showed diffuse renal tubules and the glomeruli coagulative necrosis with cystic dilatation and/or morphological distortion of some renal tubules besides damaging of the basal membrane and severe congestion of the intertubular blood vessels (El-Bahrawy, 2016).…”