In this paper published in the Journal of Veterinary Diagnostic Investigation, PhD-candidate Talita Resende from Dr. Vannucci’s lab, shares a novel diagnostic technique to detect various rotavirus species using newly developed markers.
Rotaviruses cause enteric disorders in piglets
Rotaviruses are a common causes of diarrhea in young piglets (pre-weaning). 8 groups of rotaviruses have been identified so far but rotavirus A, B, and C are the most common in the United States swine population. Clinical cases can be mild, moderate or severe depending on the strain of the virus. Control and prevention of rotaviruses infection is critical to avoid spreading the disease.
PCR commonly used to diagnose rotavirus infections
PCR on a fecal sample is a fast and reliable method to diagnose a case of rotavirus in piglets. However, rotavirus groups A, B and C are so common that PCR results often show multiple groups to be responsible for the clinical case. This is important because currently, commercial vaccines only target rotavirus group A and cross-protection against groups B and C is not effective.
Dr. Vannucci’s team at the University of Minnesota, Veterinary Diagnostic Laboratory developed a new technique to diagnose rotaviruses and differentiate between the various groups which one is responsible for the clinical signs.
Developing group-specific markers
The technique is called in situ hybridization. Briefly, the researchers developed small molecules that can bind to the genetic material (RNA) of the virus. Attached to these molecules are colored markers that can then be seen under the microscope. Until now, markers against rotavirus A were the only ones available. The team at the UMN-VDL developed probes that can attach to rotaviruses from groups B and C.
The technique is showing great promise as the researchers were able to detect as few as 1,000 rotavirus RNA copies per mL. Out of the 33 tissue samples tested, 23 were co-infected by rotavirus groups A and C (see figure).
Further evaluation needs to be conducted in the future to validate this technique.
Edit: This test is based on the recognition of genetic material not antibodies as previously written.
Rotavirus groups A, B, and C (RVA, RVB, and RVC, respectively) have been the most prevalent and pathogenic in pigs. To date, immunohistochemistry is only available for RVA because of the lack of commercial antibodies for RVB and RVC. We developed a novel in situ hybridization RNA-based chromogenic technique (ISH-RNA) to detect and subtype RVA, RVB, and RVC. We evaluated 33 samples that were reverse-transcription PCR positive for RVA, RVB, and/or RVC. ISH-RNA was able to detect as few as 10^3 RV RNA copies/mL. The new ISH-RNA test can be useful for routine investigation of rotavirus enteritis in order to guide strategies for control of the infection in pigs, but a full validation study needs to be completed. Pathogenesis studies may be conducted using ISH-RNA based on the identification of replicating virus.