Enzootic frog pathogen Batrachochytrium dendrobatidis in Asian tropics reveals high ITS haplotype diversity and low prevalence

• Published in: Scientific reports Vol. 8; no. 1; pp. 10125 - 11
• Main Authors: Mutnale, Milind C., Anand, Sachin, Eluvathingal, Lilly M., Roy, Jayanta K., Reddy, Gundlapally S., Vasudevan, Karthikeyan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-07-2018; Nature Publishing Group
• Subjects: 631/158/1469; 631/158/672; Amphibians; Batrachochytrium dendrobatidis; Bayesian analysis; Binding sites; Biodiversity; Biodiversity hot spots; Chytridiomycosis; Frogs; Fungi; Haplotypes; Humanities and Social Sciences; Infectious diseases; multidisciplinary; Pandemics; Pathogens; Science; Science (multidisciplinary); Spacer region; Tropical environments; Wildlife
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-28304-1

Emerging Infectious Diseases (EIDs) are a major threat to wildlife and a key player in the declining amphibian populations worldwide. One such EID is chytridiomycosis caused by
Batrachochytrium dendrobatidis
(
Bd
), a fungal pathogen. Aetiology of
Bd
infection is poorly known from tropical frogs in Asian biodiversity hotspots. Surveys were carried out in four biodiversity hotspots to ascertain the status of
Bd
fungus. We collected a total of 1870 swab samples from frogs representing 32 genera and 111 species. Nested PCRs revealed low prevalence (8.4%) and high
Bd
haplotype richness was revealed after sequencing. We document 57
Bd
Internal Transcribed Spacer region (ITS) haplotypes, of which 46 were unique to the global database.
Bd
ITS region showed indels at the Taqman binding site and qPCR reverse primer binding site, suggesting qPCR is unsuitable for diagnosis in Asian
Bd
coldspots. Our median-joining network and Bayesian tree analyses reveal that the Asian haplotypes, with the exception of Korea, formed a separate clade along with pandemic
Bd
GPL (
Bd
Global Panzootic Lineage) haplotype. We hypothesise that the frog populations in Asian tropics might harbour several endemic strains of
Bd
, and the high levels of diversity and uniqueness of
Bd
haplotypes in the region, probably resulted from historical host-pathogen co-evolution.