Wide genetic diversity of Blastocystis in white-tailed deer (Odocoileus virginianus) from Maryland, USA

Authors: Maloney, Jenny; JANG, YUNAH - US Department Of Agriculture (USDA); Molokin, Aleksey; George, Nadja; Santin-Duran, Monica

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2021
Publication Date: 6/21/2021
Citation: Maloney, J.G., Jang, Y., Molokin, A., George, N.S., Santin, M. 2021. Wide genetic diversity of Blastocystis in white-tailed deer (Odocoileus virginianus) from Maryland, USA. Microorganisms. https://doi.org/10.3390/microorganisms9061343.
DOI: https://doi.org/10.3390/microorganisms9061343

Interpretive Summary: Blastocystis is a gastrointestinal protist parasite frequently reported in humans and wild and domestic animals worldwide. Wildlife populations, including deer, have the potential to serve as reservoirs of parasitic diseases for both humans and domestic animals either through direct contact or through contamination of food or water resources. However, no studies of the occurrence and subtype distribution of Blastocystis in wildlife populations have been conducted in the United States. In the present study, PCR and next generation amplicon sequencing were used to determine the occurrence and subtypes of Blastocystis in a white-tailed deer (Odocoileus virginianus) population from Marlyand, USA. Blastocystis was incredibly common in this population with 88.8% (71/80) of samples positive by PCR. There was also a great deal of subtype diversity in white-tailed deer with 12 subtypes identified, ten previously reported (ST1, ST3, ST4, ST10, ST14, ST21, ST23, ST24, ST25, and ST26) and two novel subtypes (named ST30 and ST31). ST10, ST14, and ST24 were the three most commonly observed subtypes and were found in 71.8%, 42.3%, and 77.5% of Blastocystis-positive samples, respectively. Subtypes previously reported in human, ST1, ST3, or ST4, were found in 8.5% of Blastocystis-positive samples. Mixed infections with more than one subtype present in a sample were also extremely common in white-tailed deer and were observed in 90.1% of Blastocystis-positive samples. To confirm the validity of ST30 and ST31 as new subtypes of Blastocystis, MinION sequencing was used to obtain the full-length SSU rRNA gene sequence of both novel subtypes. Phylogenetic analysis and pairwise distance comparisons of full-length, barcoding region, and Santin region sequences were performed and demonstrate ST30 and ST31 as new subtypes of Blastocystis. This study is the first to subtype Blastocystis in white-tailed deer and in wildlife in the United States. White-tailed deer were found to be commonly infected/colonized with a wide diversity of subtypes including two novel subtypes, zoonotic subtypes, and subtypes frequently reported in domestic animals. Clearly more studies from white-tailed deer and wildlife in general are needed to better understand the role these populations in the transmission of Blastocystis and to clarify the epidemiology and host specificity of this ubiquitous parasite. This information will be useful to other scientists, veterinarians, wildlife biologists, and public health agencies in understanding the current status of taxonomy, epidemiology, zoonotic potential, and public health importance of Blastocystis.

Technical Abstract: Blastocystis is a gastrointestinal protist frequently reported in humans and animals worldwide. Wildlife populations, including deer, may serve as reservoirs of parasitic diseases for both humans and domestic animals either through direct contact or through contamination of food or water resources. However, no studies of the occurrence and subtype distribution of Blastocystis in wildlife populations have been conducted in the United States. PCR and next generation amplicon sequencing were used to determine the occurrence and subtypes of Blastocystis in white-tailed deer (Odocoileus virginianus). Blastocystis was common with 88.8% (71/80) of samples positive. Twelve subtypes were identified, ten previously reported (ST1, ST3, ST4, ST10, ST14, ST21, and ST23-ST26) and two novel subtypes (ST30 and ST31). To confirm the validity of ST30 and ST31, MinION sequencing was used to obtain full-length SSU rRNA gene sequences, and phylogenetic and pairwise distance analyses were performed. ST10, ST14, and ST24 were the most commonly observed subtypes. Potentially zoonotic subtypes ST1, ST3, or ST4 were present in8.5% of Blastocystis-positives. Mixed subtype infections were common (90.1% of Blastocystis-positives). This study is the first to subtype Blastocystis in white-tailed deer. White-tailed deer were found to be commonly infected/colonized with a wide diversity of subtypes including two novel subtypes, zoonotic subtypes, and subtypes frequently reported in domestic animals. More studies from wildlife are needed to better understand their role in the transmission of Blastocystis.