Morphological, molecular, and pathological studies on Prosthogonimus cuneatus in Indian peacocks (Pavo cristatus)

This report provides the first record of Prosthogonimus cuneatus infection in Indian peafowl. Chickens, turkeys, geese, ducks, and other pet birds are recognized as direct hosts of Prosthogonimus species; however, P. cuneatus has not been reported to infect peafowl globally. Here, we identify the trematode present in the bursa of the peafowl by both morphological and molecular methods, in addition to the changes in the bursal tissue induced by the parasite, using histopathology. After a necropsy examination, the trematodes were found in the bursa of Fabricius in three peafowl. Morphological and molecular approaches based on taxonomic characteristics and the sequencing of the trematode-specific internal transcribed spacer (ITS) gene, respectively, were employed for trematode identification. The consensus sequences were compared to P. cuneatus reference sequences from GenBank. In order to assess the pathology caused by the parasite, a histological study of the bursa was also performed. Trematodes were confirmed as P. cuneatus based on morphology and DNA sequencing. Further, histopathological evaluation revealed mild lymphoid depletion of the bursal follicles in both the cortex and medulla with associated thinning of the bursal follicular lining epithelium. Indian peafowl can act as a natural host of P. cuneatus. This study provides a detailed pathological and molecular analysis of P. cuneatus affecting Indian peafowl.

Mechanisms of lymphoid depletion in bowel obstruction

Background and aims: Bowel obstruction (BO) causes not only gastrointestinal dysfunctions but also systemic responses such as sepsis, infections, and immune impairments. The mechanisms involved are not well understood. In this study, we tested the hypothesis that BO leads to lymphoid depletion in primary and peripheral lymphoid organs, which may contribute to systemic responses. We also sought to uncover mechanisms of lymphoid depletion in BO. Methods: Partial colon obstruction was induced with a band in the distal colon of Sprague-Dawley rats, and wild-type and osteopontin knockout (OPN^-/-) mice. Obstruction was maintained for 7 days in rats and 4 days in mice. Thymus, bone marrow, spleen, and mesenteric lymph node (MLN) were taken for flow cytometry analysis. Results: The weight of thymus, spleen, and MLN was significantly decreased in BO rats, compared to sham. B and T lymphopoiesis in the bone marrow and thymus was suppressed, and numbers of lymphocytes, CD4⁺, and CD8⁺ T cells in the spleen and MLN were all decreased in BO. Depletion of gut microbiota blocked BO-associated lymphopenia in the MLN. Corticosterone antagonism partially attenuated BO-associated reduction of lymphocytes in the thymus and bone marrow. Plasma OPN levels and OPN expression in the distended colon were increased in BO. Deletion of the OPN gene did not affect splenic lymphopenia, but attenuated suppression of lymphopoiesis in the bone marrow and thymus in BO. Conclusions: BO suppresses lymphocyte generation and maintenance in lymphoid organs. Mechanical distention-induced OPN, corticosterone, and gut microbiota are involved in the immune phenotype in BO.

Sequential Pathology of a Genotype XIII Newcastle Disease Virus from Bangladesh in Chickens on Experimental Infection

The sequential pathology of a genotype XIII Bangladeshi strain of Newcastle disease virus (NDV) was studied in 5-weeks old chickens. Layer chickens of ISA Brown breed were inoculated through the intranasal and intraocular routes with the BD-C161/2010 strain of NDV and examined at different times post-infection (pi). NDV-infected chickens showed depression at 3 days pi (dpi) followed by dropped wings, paralysis and death starting at 4 dpi. Lungs of infected chickens showed hemorrhagic lesions starting at 24 hours pi (hpi) that was followed by pallor and slight contraction by 2 to 3 dpi and subsequently developed into severe hemorrhagic pneumonia with mononuclear cell infiltration. Hemorrhagic and necrotizing lesions were found in different visceral organs including proventriculus, intestine, gut-associated lymphoid tissues, liver and kidneys starting at 3 dpi that progressed rapidly. Severe lymphoid depletion was observed in the thymus, spleen and bursa of Fabricius starting at 1–3 dpi followed by hemorrhages, necrosis, inflammation and atrophy at 4–5 dpi. In the brain, mild neuronal lesions such as focal to diffuse encephalitis with encephalomalacia was observed at 2–3 dpi and moderate and diffuse meningoencephalitis with encephalomalacia at advanced stages. In conclusion, the BD-C161/2010 strain of NDV produced lesions typical of velogenic viscerotropic pathotype of NDV.

Histologic Effects of Concurrent Heat Stress and Coccidial Infection on the Lymphoid Tissues of Broiler Chickens

We characterized the histologic effects of two stressors (heat and coccidial infection) alone or in combination on bursa of Fabricius, thymus, and spleen in broiler chickens. Four hundred and eighty Cobb500 male chicks at 14 days of age were randomly assigned to two treatments in a 2×2 factorial design, with 15 replicates per treatment and eight birds per replicate. The treatment factors were temperature (25 and 35 C) and a mixed culture of 2.5 × 10⁵ sporulated Eimeria acervulina and Eimeria maxima oocysts (infection or no infection). Histologic lesion severity was scored in these tissues at different ages. At 21 and 28 days of age, bursal and thymic tissues from birds raised at 35 C exhibited significant increases in lymphoid depletion severity compared with those raised at 25 C. No significant differences were detected in the lymphoid depletion severity of birds infected with Eimeria when compared with uninfected birds. These results indicate that continuous exposure to heat stress-inducing temperatures results in lymphoid depletion of the bursa and thymus in broiler chickens, a potential histologic marker for the immunologic changes known to arise as a result of heat stress. Bursal and thymic atrophy are thought to contribute to immunologic changes that underlie the negative effects of heat stress on poultry production characteristics.