Cattle waste contamination is considered a major environmental concern. Improper or poor cattle waste disposal can lead to excessive nutrients, organics, metals and antimicrobial residuals in water and soils. Furthermore, since cows are known to harbor human pathogens such as parvum and pathogenic
E. coli, proper monitoring and remediation of this form of
fecal contamination is essential for maintaining viable water systems.
Detection of cattle viruses in water samples can serve as an indicator of cattle contamination. Of particular concern are bovine enteroviruses. These viruses infect the gastrointestinal tract of cows, and are excreted in feces in large numbers. Infections in cattle are typically asymptomatic or mild, but they have also been associated with diarrhea and abortions. As such, they are endemic to cattle. Additionally, bovine enteroviruses are found worldwide and they are highly stable in water.
One of the advantages of the Cow Fecal Virus ID™ service is that the entire water is sampled and filtered for bovine enteroviruses. As such, this method avoids the randomness effect of culturing and selecting bacterial isolates off a petri dish. This is a particular advantage for highly contaminated water systems with potential multiple sources of
fecal contamination.
Bovine enteroviruses are RNA viruses; therefore, a PCR (polymerase chain reaction) method called reverse transcriptase PCR (RT-PCR) must be used to transcribe the detected RNA back into DNA. PCR allows quantities of DNA to be amplified into large number of small copies of DNA sequences. This is accomplished with small pieces of DNA called primers that are complementary and specific to the viruses to be detected.
Through a heating process called thermal cycling, the double stranded DNA is denatured and inserted with complementary primers to create exact copies of the DNA fragment desired. This process is repeated rapidly many times ensuring an exponential progression in the number of copied DNA. If the primers are successful in finding a site on the DNA fragment that is specific to the virus or genome to be studied, then billions of copies of the DNA fragment will be available for detection by gel electrophoresis.
The gel electrophoresis apparatus uses an electrical field to distinguish different DNA fragments according to their molecular weights. Lighter DNA fragments will move farther along the gel than their heavier counterparts. At the end of the procedure different bands of accumulated DNA fragments will aggregate at different parts of the gel. It is this accumulation of DNA fragments that creates a band on the gel. Researchers use these bands to confirm and distinguish viral genomes.
Viruses cannot replicate themselves. They need a host organism to transcribe and replicate their genetic code. Viruses come in two genetic forms, either RNA or DNA based. Their genetic material is protected with a protein coat. Detection of virus RNA or DNA strongly indicates the presence of intact, encapsulated viruses, as free RNA or DNA quickly degrades in the environment.
To strengthen the validity of the results, the Cow Fecal Virus ID™ service should be combined with the Cow
E. coli ID™ or the Cow Bacteroidetes ID™ services. In particular, bovine enteroviruses have been shown to be present occasionally in other ruminants such as white-tailed deer; therefore a positive result should be corroborated with other analyses that target cattle
fecal contamination. The Cow
E. coli ID™ service is designed around the principle that certain strains of
E. coli are pathogenic in cattle. As such, this service targets the heat labile toxin IIa (LTIIa) gene from enterotoxigenic
E. coli as an indicator of cattle
fecal contamination. The Cow Bacteroidetes ID™ service analyzes for fecal Bacteroidetes that are found in cattle.
