Diagnosis, isolation, and description of a novel amnoonvirus recovered from diseased fancy guppies, Poecilia reticulata

Authors: SOTO, ESTEBAN - University Of California, Davis; Lafrentz, Benjamin; YUN, SUSAN - University Of California, Davis; MEGARANI, DOROTHEA - University Of Florida; HENDERSON, EILEEN - University Of California, Davis; PIEWBANG, CHUTCHAI - Chulalongkorn University; Johnston, Amber; TECHANGAMSUWAN, SOMPORN - Chulalongkorn University; NG, TERRY FEI FAN - University Of Georgia; WARG, JANET - US Department Of Agriculture (USDA); SURACHETPONG, WIN - Kasetsart University; SUBRAMANIAM, KUTTICHANTRAN - University Of Florida

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2024
Publication Date: 5/10/2024
Citation: Soto, E., Lafrentz, B.R., Yun, S., Megarani, D., Henderson, E., Piewbang, C., Johnston, A.E., Techangamsuwan, S., Ng, T., Warg, J., Surachetpong, W., Subramaniam, K. 2024. Diagnosis, isolation, and description of a novel amnoonvirus recovered from diseased fancy guppies, Poecilia reticulata. Journal of Fish Diseases. 47:e13937. https://doi.org/10.1111/jfd.13937.
DOI: https://doi.org/10.1111/jfd.13937

Interpretive Summary: Guppies are a very popular ornamental fish for hobbyists and important for the ornamental fish industry. In this research, a previously undescribed virus was isolated from guppies exhibiting mortality and clinical signs of disease. The signs of disease were similar to other fish diseases and only mild cellular changes were noted in organs of infected fish. The virus was characterized utilizing whole genome sequencing and other molecular tools, and the results indicated that the virus was closely related to tilapia lake virus (TiLV), but phylogenetically distinct. It was proposed that the classification of this new virus, fancy tailed guppy virus (FTGV), be a member of the family Amnoonviridae, with the name Tilapinevirus poikilos (from the Greek “poikilos”, meaning of many colors; various sorts, akin to “poecilia”). Future research will assess the ability of the virus to cause disease experimentally and determine its significance for aquaculture and hobbyists.

Technical Abstract: The guppy, Poecilia reticulata, is one of the most common cultured ornamental fish species, and a popular pet fish highly desired by hobbyists worldwide due to its availability of brilliantly colored fish of many varieties. The susceptibility of guppy to diseases presents a remarkable concern for both breeders and hobbyists. In this study, we report the emergence of disease in fancy guppies caused by a previously uncharacterized virus in the United States. This virus was isolated from moribund guppies in two separate outbreaks in California and Alabama, from December 2021 to June 2023. The infected guppies showed acute mortality shortly after shipping, showing nonspecific clinical signs including lethargy, anorexia, hanging at the water surface, gill pallor, mild to moderate coelomic distension, occasional skin lesions, and protruding scales. Histological changes in affected fish were mild and non-specific; however, liver and testes from moribund fish were positive for virus using immunohistochemistry and in situ hybridization, although the latter was weak. The virus was successfully recovered following tissue inoculation on epithelioma papulosum cyprini and snakehead fish cell lines). Whole genome sequencing and phylogenetic analyses revealed nucleotide and amino acid homologies from 78.3% to 91.2%, and 78.2% to 97.7%, respectively, when comparing the guppy virus genomes to TiLV isolates. Based on the criteria outlined herein, we propose the classification of this new virus, fancy tailed guppy virus (FTGV), as a member of the family Amnoonviridae, with the name Tilapinevirus poikilos (from the Greek “poikilos”, meaning of many colors; various sorts, akin to “poecilia”).