Ferlaviruses, in the family Paramyxoviridae, are important pathogens of snakes, but diagnosis can be challenging. Standard methods include detection of viral RNA using various PCRs. The genus Ferlavirus includes a genetically diverse group of viruses, making virus detection even more complex. Previously described methods have been shown to be lacking in both sensitivity and specificity, and multiple anecdotal reports are available of inconsistent results when testing for these viruses in single animals as well as between laboratories. In order to help optimize methods for virus detection, this study compared two nested PCRs1,3 with a single-round PCR2 for the detection of a wide range of Ferlaviruses using both cell culture isolates and tissues from corn snakes (Pantherophis guttatus) infected with defined virus genotypes. In addition, specificity was tested using DNA or RNA from various common reptile pathogens as well as tissues from uninfected snakes. The PCR according to Hyndman et al.2 performed the best. It was able to detect between 5x10-2 and 5x10-3 ng of RNA from genogroup A and B Ferlavirus cell culture isolates, and between 5x10-1 and 5x10-2 ng of RNA from genogroup C and “tortoise” cell culture isolates. It was also able to detect genogroup A, B, and C Ferlaviruses in lung and brain tissues of infected snakes in more cases than either of the other two methods used. This PCR, therefore, represents an improvement in the diagnosis of this group of important pathogens in reptiles.
1. Ahne W, Batts WN, Kurath G, Winton JR. Comparative sequence analyses of sixteen reptilian paramyxoviruses. Virus Res. 1999;63:65–74.
2. Hyndman TH, Marschang RE, Wellehan JFX, Nicholls PK. Isolation and molecular identification of Sunshine virus, a novel paramyxovirus found in Australian snakes. Inf Gen Evol. 2012;12:1436–1446.
3. Tong S, Chern SW, Li Y, Pallansch MA, Anderson LJ. Sensitive and broadly reactive reverse transcription-PCR assays to detect novel paramyxoviruses. J Clin Microbiol. 2008;46:2652–2658.