Chemotactic response of lymphocytes in chicken embryos infected with Mycoplasma gallisepticum

Pathologic lesions caused by coinfection of Mycoplasma gallisepticum and H3N8 low pathogenic avian influenza virus in chickens

Chickens were infected under experimental conditions with Mycoplasma gallisepticum and low pathogenic avian influenza (LPAI) strain A/mallard/Hungary/19616/07 (H3N8). Two groups of chickens were aerosol challenged with M. gallisepticum strain 1226. Seven days later, one of these groups and one mycoplasma-free group was challenged with LPAI H3N8 virus; one group without challenge remained as negative control. Eight days later, the birds were euthanized and examined for gross pathologic and histologic lesions. The body weight was measured, and the presence of antimycoplasma and antiviral antibodies was tested before the mycoplasma challenge, before the virus challenge, and at the end of the study to confirm both infections. Chickens in the mycoplasma-infected group developed antibodies against M. gallisepticum but not against the influenza virus. Chickens of the group infected with the influenza virus became serologically positive only against the virus, while the birds in the coinfected group developed antibodies against both agents. The LPAI H3N8 virus strain did not cause decrease in body weight and clinical signs, and macroscopic pathological lesions were not present in the chickens. The M. gallisepticum infection caused respiratory signs, airsacculitis, and peritonitis characteristic of mycoplasma infection. However, the clinical signs and pathologic lesions and the reduction in weight gain were much more significant in the group challenged with both M. gallisepticum and LPAI H3N8 virus than in the group challenged with M. gallisepticum alone.

Mycoplasma meleagridis-induced lesions in the tarsometatarsal joints of turkey embryos

Mycoplasma meleagridis (MM) has the ability to cause bone deformity in turkey poults. However, few pathological lesions have been described and no evidence of MM-induced damage to the bones has been shown. In this study, 17-day-old turkey embryos were inoculated with MM into the allantoic cavity. On the 27th day, eight of the 22 embryos presented with curved toes. Scanning electron microscopy of the tarsometatarsal joints showed fissures in the cartilage. Histological sections of the joints revealed only the infiltration of cells with eosinophilic granules. Immunohistochemical staining (IHS) showed the presence of MM in the aggregates of the bone marrow cells and the cells with eosinophilic granules. Some of these cells were harvested by laser capture microdissection (LCM), lysed, and used as template DNA. With a pair of MM-specific primers in a conventional polymerase chain reaction (PCR), a gene product was amplified, and it comigrated with the MM DNA, which indicates that these captured cells contained MM DNA. Thus, this research shows that inoculation of MM into the turkey embryos produced joint lesions and caused cellular infiltration within the bones.

Morphologic Changes in Chicken Cells AfterIn VitroExposure to Mycoplasma gallisepticum

Mycoplasma gallisepticum (MG) was used to expose chicken peripheral blood lymphocytes (PBLs), red blood cells (RBCs), heterophils, and chicken tumor cells (MSB-1 and HD-11 cells). Incubation of PBLs with MG for 3 hr resulted in extensive clumping of lymphocytes. Incubation of the MSB-1 cells with MG also caused clumping of the cells, with many of the cells showing perforations and others showing capping of the surface projections. Incubation of RBCs with MG resulted in an altered cell surface morphology, a decrease in cell size, and perforation. There were no discernible changes on the surface of the heterophils and the HD-11 cells. However, the HD-11 cells appeared to have a decreased ability to attach to the surface of the plastic and to have a decreased ability to respond to chemoattractant fMLP after 24 hr of incubation. These results suggest that, under the conditions used, MG caused certain damage to peripheral blood cells and a significant decrease in chemotactic response in the HD-11 cells.

Mycoplasma gallisepticum--induced alterations in cytokine genes in chicken cells and embryos

Mycoplasma gallisepticum (MG) was used to infect the MSB-1 cells, the HD-11 cells, and chicken embryos. The RNA from these cells and the embryonic spleen cells were extracted and assayed for the expression of cytokine genes using reverse transcription-polymerase chain reaction. The results showed that MG infection suppressed the expression of the IL-8 gene in the MSB-1 cells and enhanced the expression of the IL-8 and IL-6 genes in the HD-11 cells; a slightly increased expression of macrophage inflammatory protein-1beta (MIP-1beta) in MG-infected spleen cells was noted. Because of the divergent response in cytokine expression in different cell types, more work needs to be done before a correlation between the cytokine gene expression and the pathogenesis of a disease can be made.