Detection of Antibodies to a Pathogenic Mycoplasma in American Alligators (Alligator mississippiensis), Broad-Nosed Caimans (Caiman latirostris), and Siamese Crocodiles (Crocodylus siamensis)

Abstract

An epidemic of pneumonia with fibrinous polyserositis and multifocal arthritis emerged in captive American alligators (Alligator mississippiensis) in Florida, United States, in 1995. Mycoplasma alligatoris sp. nov. was cultured from multiple organs, peripheral blood, synovial fluid, and cerebrospinal fluid of affected alligators. In a subsequent experimental inoculation study, the Henle-Koch-Evans postulates were fulfilled for M. alligatoris as the etiological agent of fatal mycoplasmosis of alligators. That finding was remarkable because mycoplasmal disease is rarely fatal in animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies produced by alligators in response to M. alligatoris exposure was developed by using plasma obtained from naturally infected alligators during the original epidemic. The assay was validated by using plasma obtained during an experimental dose-response study and applied to analyze plasma obtained from captive and wild crocodilian species. The ELISA reliably detected alligator seroconversion (P < 0.05) beginning 6 weeks after inoculation. The ELISA also detected seroconversion (P < 0.05) in the relatively closely related broad-nosed caiman Caiman latirostris and the relatively distantly related Siamese crocodile Crocodylus siamensis following experimental inoculation with M. alligatoris. The ELISA may be used to monitor exposure to the lethal pathogen M. alligatoris among captive, repatriated, and wild crocodilian species.An epidemic of mycoplasmosis emerged in a collection of American alligators (Alligator mississippiensis) in Florida in 1995 (4, 8). Thirty-three 200-to 300-kg adult male alligators died, and 13 moribund alligators were euthanatized within 1 month of the index case. Lesions observed at necropsy ranged from mild interstitial and peribronchiolar pneumonia to fibronecrotic pneumonia. Extrapulmonary complications included pericarditis, myocarditis, and multifocal arthritis. Mycoplasma alligatoris proposed sp. nov. was isolated from multiple tissues, blood, synovial fluid, and cerebrospinal fluid of affected alligators. In a pilot experimental inoculation study (5, 6), healthy alligators were inoculated with M. alligatoris strain A21JP2 T (ATCC 700619) to reproduce the disease and fulfill the HenleKoch-Evans postulates (11) for M. alligatoris as the etiological agent of synovitis, polyserositis, and pneumonia of alligators. The results were remarkable because, except for bovine and caprine pleuropneumonia, mycoplasmal disease is rarely fatal in animals.The origin of the 1995 epidemic remains unknown, but the disease may emerge under conditions of captivity. Crocodilians are frequently sold or traded among collections, exhibits, zoos, and ranches. Many collections include multiple species of crocodilians. Some crocodilians from commercial ranches are repatriated after "head-starting" hatchlings from eggs collected in the wild, a potential vector for catastrophic infection of wild populations if lethal disease emerges in captivity. A validated ser...

Assessment of selected biochemical parameters and humoral immune response of Nile crocodiles (<i>Crocodylus niloticus</i>) experimentally infected with <i>Trichinella zimbabwensis</i>

“…Previous studies have shown that the intensity of infection cannot always be correlated with antibody titres (Ludovisi et al 2013;Pozio et al 2002;Vu Thi et al 2010). In crocodiles, interpretation of antibody titres is also complicated, as the immune response may also be influenced by age, temperature, season, and hormone levels (Brown et al 2001;Ludovisi et al 2013). Gamble et al (1996) reported on the efficacy of enzyme immunoassays to detect light infections and indicated that the time period between infection and sero-conversion of the host was problematic in surveillance.…”

“…In crocodiles, the potential effects of individual hormonal status, temperature fluctuations and age on the immune response (Brown et al 2001;Ludovisi et al 2013) may explain these phenomena. However, despite the observed differences between infection intensity and time to seroconversion, the lower humoral response associated with higher infection levels may also be the result of larvae being released at different intervals, which could result in smaller but repetitive responses from the host.…”

Validation and Use of an Indirect Enzyme-Linked Immunosorbent Assay for Detection of Antibodies to West Nile Virus in American Alligators (Alligator Mississippiensis) in Florida

“…Recently, an indirect ELISA was developed for detecting antibodies to WNV in chickens (Johnson et al, 2003) and multiple species of wild birds (Ebel et al, 2002;Blitvich et al, 2003). To determine WNV exposure in large numbers of samples from wild and farmed alligators, we developed an indirect ELISA using a rabbit polyclonal antibody produced against alligator immunoglobulins as the secondary antibody (Brown et al, 2001). Here we present our validation findings using plasma of captive alligators that survived an epizootic of WNV infection at an alligator farm in Florida (USA).…”

Role of sialidase in Mycoplasma alligatoris-induced pulmonary fibroblast apoptosis

“…M. alligatoris can be cultured in high numbers from the lower respiratory tract of infected individuals, where pathologic changes include fibrinous pleuritis, pulmonary edema and congestion, and diffuse interstitial to fibronecrotic pneumonia as early as 1 wk after exposure (Brown et al, 2001b;Brown et al, 2001c;Pye et al, 2001). A genome survey revealed that M. alligatoris strain A21JP2 T notably possesses the "spreading factors" sialidase and hyaluronidase, a combination unprecedented among mycoplasmas but common among other invasive pathogens, which could degrade host extracellular matrix (ECM) glycans during nutrient scavenging to contribute to disease (Brown et al, 2004).…”