science

Identify the killer of the endangered Christmas Island reptile

Identify the killer of the endangered Christmas Island reptile

One of the endangered species of Australian lizards: the Lester gecko. Credit: Parks Australia

The bacteria responsible for the death of endangered species.

With the decimation of the wild groups, only the Lester gecko and blue-tailed hookworm remain in captivity. Researchers at the University of Sydney have discovered a bacterium that may cause its possible extinction.

The numbers of native reptiles on Christmas Island have seen a sharp decline with two species, the Lester gecko and the blue-tailed eagle, have completely disappeared from the wild. While previously the main driver of this decline was the potential predation of invasive species and habitat destruction, the silent killer now threatens to wipe out the species altogether.

And those bred in captivity in the Australian Territory of the Indian Ocean are dying mysteriously, putting the two species – which number only around 1,000 – at risk of extinction. Veterinarians from the University of Sydney, the Australian Register of Wildlife Health and the Taronga Conservation Society of Australia have now discovered the cause of these deaths: a germ, Enterococcus lacertideformus (E. lacertideformus).

Injured gecko

An infected gecko shows severe swelling of the head and face associated with an Enterococcus lacertideformus infection. Credit: Jessica Agios

The bacterium was discovered in 2014 after captive reptiles developed facial abnormalities and lethargy, and some even died. Samples were collected and analyzed using microscopy and genetic testing. Researchers’ results published in Frontiers in Microbiology, Will inform antibiotic trials on reptiles to see if the infection can be treated.

The bacteria grow in the animal’s head, then into its internal organs, before eventually causing death. It can spread by direct contact – including through reptile mouths, or by reptiles biting each other – often during breeding season fights.

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“This means that healthy captive animals should be kept away from infected animals and they should also be kept away from areas where the affected animals have been,” said Jessica Agios, associate researcher and doctoral candidate at the Sydney College of Veterinary Sciences.

Jessica Agios

PhD researcher Jessica Agios sheds light on endangered lizards in the field on Christmas Island to see if they are infected with Enterococcus lacertideformus. Credit: Jessica Agios

Ms Agios and the research team not only identified the bacteria, but also decoded their genetic makeup using whole genome sequencing.

Certain genes have been identified that are likely related to the ability of the bacteria to infect its host, invade its own tissues, and evade the immune system.

“We also found that bacteria can surround themselves with a biofilm – a ‘community of bacteria’ that can help them survive,” said Ms. Agios.

Understand how E lacertideformus They produce and maintain biofilms and may provide insights into how other types of biofilm-forming bacteria are treated. “

Research into the genetic code indicates that the deadly bacteria were susceptible to most of the antibiotics.

“This indicates that infected animals can be treated successfully. This is what we need to define now,” said Professor David Fallen, co-head of research and PhD supervisor at Ms Agios.

In another effort to protect the endangered Christmas Island reptiles, a group of blue-tailed sausages has been established in the Cocos Islands. Mrs. Agios played a critical role in the transport, and tested reptiles in the Cocos Islands to ensure that they were free of E lacertideformus.

“It is critical that we act now to ensure the survival of these native reptiles,” said Ms. Agios.

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Reference: “Genomic insights into the pathogenesis of the biofilm narration Enterococcus s. Bacteria (Enterococcus lacertideformus) Identified in reptiles “
Jessica Esther Agios, David Norton Fallen, Carrie Rose, and John Sebastian Eden, March 2, 2021, Frontiers in Microbiology.
DOI: 10.3389 / fmicb.2021.635208

Announcement: The authors thank Westmead Institute for Medical Research, Sydney College of Veterinary Sciences – University of Sydney, Australian Register of Wildlife Health – Taronga Conservation Society of Australia, and Christmas Island National Park – Parks Australia for their logistical and financial support.

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