Multicentric Cryptococcosis in a Congo African Grey Parrot ( Psittacus erithacus erithacus).

An approximately 10-year-old, female Congo African grey parrot ( Psittacus erithacus erithacus) developed progressive, unilateral exophthalmos and buphthalmos. Survey radiographs revealed a large, coelomic, soft tissue mass, which was confirmed on computed tomography scan. Aspirates of both the contents of the buphthalmic globe and coelomic mass were consistent with Cryptococcus species. Initial results were later confirmed with serum antigen latex agglutination and polymerase chain reaction testing, and the organism was then identified as Cryptococcus neoformans with DNA sequencing. During the course of 1 year, the bird was treated with combinations of oral terbinafine, fluconazole, and flucytosine, as well as intraocular amphotericin B. The coelomic mass dramatically decreased in size during the course of treatment, but the globe continued to enlarge. The bird died after exhibiting ataxia and seizures approximately 13 months after initial diagnosis, and necropsy confirmed colonization of the cerebrum and meninges with Cryptococcus. Cryptococcus remains a rare fungal disease of birds that is often refractory to treatment.

Chronic Mycoplasma conjunctivitis in house finches: host antibody response and M. gallisepticum VlhA expression.

Previous studies have shown that house finch field isolates of Mycoplasma gallisepticum (MG) vary in virulence and ability to induce an antibody response. After experimental inoculation, MG causes persistent, severe disease in a subset of individuals. In this study, we further characterized MG infection using five field isolates, with an emphasis on chronically diseased birds. After experimental inoculation of house finches, MG load was measured by quantitative PCR and anti-MG antibody responses were measured by ELISAs. Birds with chronic disease had significantly higher pathogen loads and antibody responses than did birds without chronic disease. Using a monoclonal antibody (MAb86) specific for a variant of the MG VlhA adhesin and immunodominant surface protein, we show that VlhA expression differs among MG isolates in this study, and that in vivo VlhA changes occur in house finches infected with MG. Overall, our results suggest that chronic MG disease has a strong pathogen-mediated component.

House finch populations differ in early inflammatory signaling and pathogen tolerance at the peak of Mycoplasma gallisepticum infection.

Host individuals and populations often vary in their responses to infection, with direct consequences for pathogen spread and evolution. While considerable work has focused on the mechanisms underlying differences in resistance-the ability to kill pathogens-we know little about the mechanisms underlying tolerance-the ability to minimize fitness losses per unit pathogen. Here, we examine patterns and mechanisms of tolerance between two populations of house finches (Haemorhous [formerly Carpodacus] mexicanus) with different histories with the bacterial pathogen Mycoplasma gallisepticum (MG). After infection in a common environment, we assessed two metrics of pathology, mass loss and eye lesion severity, as proxies for fitness. We calculated tolerance using two methods, one based on pathology and pathogen load at the peak of infection (point tolerance) and the other based on the integrals of these metrics over time (range tolerance). Alabama birds, which have a significantly longer history of exposure to MG, showed more pronounced point tolerance than Arizona birds, while range tolerance did not differ between populations. Alabama birds also displayed lower inflammatory cytokine signaling and lower fever early in infection. These results suggest that differences in inflammatory processes, which can significantly damage host tissues, may contribute to variation in tolerance among house finch individuals and populations. Such variation can affect pathogen spread and evolution in ways not predictable by resistance alone and sheds light on the costs and benefits of inflammation in wild animals.

Pathogenicity and immunogenicity of three Mycoplasma gallisepticum isolates in house finches (Carpodacus mexicanus).

Mycoplasma gallisepticum (MG) has become a common cause of conjunctivitis in free-living house finches (Carpodacus mexicanus) since its emergence in the early 1990s. To date, temporal and spatial genotypic variation in MG has been documented, but phenotypic variation in pathogenicity and immunogenicity has not been examined. House finches were inoculated with MG isolates Virginia (VA)1994, California (CA)2006, or North Carolina (NC)2006, which were cultured from free-living house finches with conjunctivitis in 1994, 2006, and 2006, respectively. Infection with NC2006 resulted in the most severe eye lesions, highest pathogen loads, and highest levels of pathogen-specific lachrymal and serum antibodies. Infection with CA2006 caused the least severe eye lesions, lowest pathogen load, and lowest levels of antibodies. A small number of birds in each group developed protracted, severe disease in spite of robust antibody responses, suggesting that immunopathology may contribute to the lesions. Immunoblot analyses indicated that isolates are antigenically similar; thus, there may be partial cross-protection if a house finch encounters two or more strains of MG throughout the course of its lifetime. This study provides evidence that MG strains or strain variants circulating in house finch populations vary in their ability to cause disease, induce antibody responses, and persist in the host.

Production of house finch (Carpodacus mexicanus) IgA specific anti-sera and its application in immunohistochemistry and in ELISA for detection of Mycoplasma gallisepticum-specific IgA.

The IgA antibody response plays a vital role in mucosal immunity because it functions to neutralize pathogens at the mucosal surface and thus impedes attachment to underlying tissues. Although the importance of IgA in the mucosal immunity of galliform birds has been established, studies examining IgA-based immunity in passerine birds are lacking, perhaps due in part to the absence of reagents that can detect passerine IgA. A 469 base pair region of the house finch (Carpodacus mexicanus) IgA heavy chain was PCR-amplified from spleen cDNA and sequenced. The predicted amino acid sequence was found to share 55% and 46% identity with the IgA heavy chain of mallard (Anas platyrhynchos) and chicken (Gallus gallus), respectively. The heavy chain fragment was produced using a bacterial expression system and purified. Rabbit anti-sera were generated against the recombinant protein. The anti-sera reacted with a single house finch serum protein ( approximately 50-55kDa) in Western blot. The anti-sera were used to identify plasma cells in the Harderian gland and conjunctiva of house finches with conjunctivitis associated with Mycoplasma gallisepticum infection. The anti-sera were also utilized in an ELISA to detect M. gallisepticum-specific IgA antibodies in lachrymal samples of infected finches.

Detection and quantification of Mycoplasma gallisepticum genome load in conjunctival samples of experimentally infected house finches (Carpodacus mexicanus) using real-time polymerase chain reaction.

A TaqMan-based real-time, quantitative polymerase chain reaction (qPCR) assay utilizing the mgc2 gene was developed to detect Mycoplasma gallisepticum in conjunctival swabs of experimentally infected house finches. The assay was demonstrated to be quantitative by the standard curve method with reproducible results within runs and between runs. The detection limit of the mgc2 assay was examined using two standards. The test had a detection limit of less than 14 copies per reaction when tested with a plasmid standard and less than 10 copies per reaction when tested with M. gallisepticum genomic DNA. All M. gallisepticum-negative birds (10 specific pathogen free chickens and 10 house finches) were negative by mgc2 qPCR assay. Existing evidence suggests that an important part of M. gallisepticum pathogenesis includes both its attachment to and invasion of host cells. Thus, our test also made use of rag-1 as an internal control gene. The rag-1 qPCR results showed that host cell quantity varied greatly between conjunctival samples. After inoculation, M. gallisepticum levels in the house finch conjunctiva increased over the 7-day period post infection. The bird with the most pronounced clinical conjunctivitis harboured the highest level of M. gallisepticum and the bird that did not develop conjunctivitis had very low numbers of M. gallisepticum. Thus, it appears that development of conjunctivitis may correlate with M. gallisepticum load.