Development of a quantitative PCR assay for measurement of trichechid herpesvirus 1 load in the Florida manatee ( Trichechus manatus latirostris)

Identification and Prevalence of a Gammaherpesvirus in Free-Ranging Northern Brown Bandicoots (Isoodon macrourus)

Herpesviruses have been reported in several Australian marsupial species, with an overt, sometimes fatal disease described in macropods. Our study identifies a gammaherpesvirus in northern brown bandicoots (Isoodon macrourus) and provides virus prevalence data for bandicoots in southeast Queensland, Australia. Herpesvirus DNA was detected using pan-Herpesviridae family primers in a nested PCR format. Samples from 35 northern brown bandicoots were screened, including whole blood (n=29), oropharyngeal swabs (n=34), urine (n=22), and feces (n=23). Combining all sample types, herpesvirus DNA was detected at a total prevalence of 51% (18/35). Whole blood and oropharyngeal swabs proved to be the optimal samples for detection of this virus, with prevalences of 34% and 38%, respectively. Herpesvirus DNA was detected in 4.5% (1/22) of urine samples and not at all in fecal samples. Detection of herpesvirus was more likely in males than females. Animals were trapped at eight different locations, and at all but one location at least one herpesvirus positive animal was detected. This study indicates a high prevalence of the virus within northern brown bandicoot populations in southeast Queensland. Further research is required to understand the clinical manifestations, if any, of herpesvirus infection in this species and how this may affect populations in the face of stressors such as land clearing and habitat fragmentation.

A novel technique for isolating DNA from Tempus™ blood RNA tubes after RNA isolation

Objective

We use Tempus blood RNA tubes (Applied Biosystems) during health assessments of American moose (Alces alces spp.) as a minimally invasive means to obtain RNA. Here we describe a novel protocol to additionally isolate high-quality DNA from the supernatant remaining after the RNA isolation methodology. Metrics used to qualify DNA quality included measuring the concentration, obtaining a DNA integrity number from a genomic DNA ScreenTape assay (Agilent), and running the isolated DNA on an agarose gel.

Results

Of the 23 samples analyzed, the average DNA concentration was 121 ng/µl (range 4–337 ng/µl) and a genomic DNA ScreenTape assay of seven samples indicated high DNA integrity values for 6 of the 7 samples (range 9.1–9.4 out of 10). Of the DNA sent for genotyping by sequencing, all proved to be of sufficient integrity to yield high-quality next-generation sequence results. We recommend this simple procedure to maximize the yield of both RNA and DNA from blood samples.

DEVELOPMENT AND VALIDATION OF QUANTITATIVE PCR ASSAYS TO MEASURE CYTOKINE TRANSCRIPT LEVELS IN THE FLORIDA MANATEE ( TRICHECHUS MANATUS LATIROSTRIS)

Cytokines have important roles in the mammalian response to viral and bacterial infections, trauma, and wound healing. Because of early cytokine production after physiologic stresses, the regulation of messenger RNA (mRNA) transcripts can be used to assess immunologic responses before changes in protein production. To detect and assess early immune changes in endangered Florida manatees ( Trichechus manatus latirostris), we developed and validated a panel of quantitative PCR assays to measure mRNA transcription levels for the cytokines interferon (IFN)-γ; interleukin (IL)-2, -6, and -10; tumor necrosis factor-α; and the housekeeping genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-actin (reference genes). Assays were successfully validated using blood samples from free-ranging, apparently healthy manatees from the east and west coasts of central Florida, US. No cytokine or housekeeping gene transcription levels were significantly different among age classes or sexes. However, the transcription levels for GAPDH, IL-2, IL-6, and IFN-γ were significantly higher ( P<0.05) in manatees from the east coast of Florida than they were from those from the west coast. We found IL-10 and β-actin to be consistent between sites and identified β-actin as a good candidate for use as a reference gene in future studies. Our assays can aid in the investigation of manatee immune response to physical trauma and novel or ongoing environmental stressors.