Evan Landis,

Sponsor or Client: 

Title:

An investigation of ranavirus species present in Arizona wild frog populations

Abstract:

In 2022, three ranavirus-positive lowland leopard frogs (Rana yavapaiensis) were found dead by Arizona Game and Fish (AZGF). While this is not the first positive result detected in Arizona, this marks the first time wild frogs have been found dead with ranavirus as the likely cause. In Arizona, Ambystoma tigrinum virus (ATV) is the singular ranavirus type that has been detected, but only in salamander populations. While another species of ranavirus, Frog virus 3 (FV3), is well known for epizootics in wild frog populations, it has never been detected in Arizona. Detection, however, is complicated by testing limitations. Tests used during general surveillance are not specific to ranavirus species, requiring genetic sequencing to determine the viral species present. Since more and more unusual cases such as this are being detected in frog populations across Arizona, we tested the frogs discovered by AZGF and samples from other cases to better understand the relationship between frog populations and ranavirus species in Arizona. For this evaluation, we extracted DNA from internal tissues or swabs and used qPCR to determine viral load. Next, we utilized Sanger sequencing to determine the species of ranavirus for each sample. A better understanding of ranavirus diversity and host range in Arizona is critical for management agencies working to protect at-risk species. Future work will aim to improve detection methods as well as expand our knowledge of the environmental conditions that influence epizootics and pathogen introductions.