Upper respiratory tract disease in the gopher tortoise is caused by Mycoplasma agassizii

Upper respiratory tract disease (URTD) has been observed in a number of tortoise species, including the desert tortoise (Gopherus agassizii) and the gopher tortoise (Gopherus polyphemus). Clinical signs of URTD in gopher tortoises are similar to those in desert tortoises and include serous, mucoid, or purulent discharge from the nares, excessive tearing to purulent ocular discharge, conjunctivitis, and edema of the eyelids and ocular glands. The objectives of the present study were to determine if Mycoplasma agassizii was an etiologic agent of URTD in the gopher tortoise and to determine the clinical course of the experimental infection in a dose-response infection study. Tortoises were inoculated intranasally with 0.5 ml (0.25 ml/nostril) of either sterile SP4 broth (control group; n = 10) or 10(8) color-changing units (CCU) (total dose) of M. agassizii 723 (experimental infection group; n = 9). M. agassizii caused clinical signs compatible with those observed in tortoises with natural infections. Clinical signs of URTD were evident in seven of nine experimentally infected tortoises by 4 weeks postinfection (p.i.) and in eight of nine experimentally infected tortoises by 8 weeks p.i. In the dose-response experiments, tortoises were inoculated intranasally with a low (10(1) CCU; n = 6), medium (10(3) CCU; n = 6), or high (10(5) CCU; n = 5) dose of M. agassizii 723 or with sterile SP4 broth (n = 10). At all time points p.i. in both experiments, M. agassizii could be isolated from the nares of at least 50% of the tortoises. All of the experimentally infected tortoises seroconverted, and levels of antibody were statistically higher in infected animals than in control animals for all time points of >4 weeks p.i. (P < 0.0001). Control tortoises in both experiments did not show clinical signs, did not seroconvert, and did not have detectable M. agassizii by either culture or PCR at any point in the study. Histological lesions were compatible with those observed in tortoises with natural infections. The numbers of M. agassizii 723 did not influence the clinical expression of URTD or the antibody response, suggesting that the strain chosen for these studies was highly virulent. On the basis of the results of the transmission studies, we conclude that M. agassizii is an etiologic agent of URTD in the gopher tortoise.

Taxonomic analysis of the tortoise mycoplasmas Mycoplasma agassizii and Mycoplasma testudinis by 16S rRNA gene sequence comparison

The nucleotide sequences of the 16S rRNA genes of two mycoplasmas, Mycoplasma agassizii (proposed sp. nov.) and Mycoplasma testudinis, isolated from tortoises were determined and used for taxonomic comparisons. Signature nucleotide sequence motifs and overall sequence similarities to other mollicutes positioned these mycoplasmas in the M. hyorhinis and M. pneumoniae phylogenetic groups, respectively. A third, previously unrecognized tortoise mycoplasma was detected by 16S rRNA gene amplification and sequence analysis and was positioned in the M. fermentans phylogenetic group. The 16S rRNA gene of Acholeplasma laidlawii was similarly detected in a tortoise isolate, showing that diverse mollicutes can share the same family of reptilian host.

The effects of serpin gene mutations on the distinctive pathobiology of cowpox and rabbitpox virus following intranasal inoculation of Balb/c mice

Intranasal infection of Balb/c mice with 106 plaque forming units (PFU) of wild-type cowpox virus (CPV) and rabbitpox virus (RPV) induced strikingly different pulmonary pathology despite nearly identical clinical signs of illness and LD50. Intranasal infection with CPV induced severe peribronchial, peribronchiolar, and perivascular hemorrhage with a mixed inflammatory cell infiltrate, bronchial and bronchiolar epithelial cell hyperplasia with intracytoplasmic acidophilic inclusion bodies, and alveolar hemorrhage and edema. In contrast, infection with RPV induced a mixed peribronchial and peribronchiolar inflammatory cell infiltrate, multifocal areas of bronchiolar epithelial cell coagulation necrosis, alveolar edema, and a conspicuous absence of pulmonary hemorrhage. Viremia was not detected following CPV infection and only 1 of 11 mice had brain-associated virus at death. Mice infected with RPV exhibited a viremia 2-3 days after infection and all mice had virus associated with the brain at death. Mice infected with viruses containing certain serine protease inhibitor (SPI) gene mutations (CPV delta SPI-1, CPV delta SPI-3, and RPV SPI-1-) exhibited no difference in clinical disease manifestation when compared with those infected with wild-type viruses. However, inactivation of the SPI-2 genes in either CPV or RPV resulted in disease attenuation and alteration of pulmonary pathology. Mice infected with the CPV delta SPI-2 mutant showed decreased pulmonary hemorrhage, reduced inflammation, and an absence of alveolar edema, while mice infected with the RPV delta SPI-2 mutant had a marked increase in intrapulmonary inflammatory cells and only a transient viremia.