What is Hobi-like pestivirus? Where is it present currently?
The Hobi-like pestivirus, also described as BVDV3 and atypical pestivirus, is from the same viral genus of BVDV. This virus was first detected in Brazilian fetal calf serum in the early 2000s and later in buffalo from the same country. There are an increasing number of reports of Hobi-like pestivirus in recent years. It has been detected in cattle, fetal calf serum and cell culture from Brazil, Italy, Thailand, Bangladesh, India and Australia. Clinical signs are indistinguishable from infection caused by BVDV in cattle. Animals can show slowed growth, decrease in milk production, respiratory disease, leucopenia and reproductive problems. This virus also has been identified in persistently infected calves that develop a syndrome similar to mucosal disease.
Why should Hobi-like pestivirus be important to U.S. veterinarians and beef/dairy producers?
Hobi-like pestivirus is a threat for animal health, because it causes the same disease as BVDV. This virus has implications for control and eradication programs for BVD, and some current BVDV laboratory tests are not able to detect/differentiate it. Then, if there is a failure in detection of Hobi-like pestivirus, the infection can be introduced or reintroduced in a herd that was pestivirus free. If a native herd for Hobi-like pestivirus is infected, the consequences may be greater, because the animals do not have protection. In addition, no vaccines are available to specifically prevent Hobi-like pestivirus infection in cattle. Moreover, taking into account the antigenic differences, available vaccines containing BVDV1 and BVDV2 are not effective in providing cross-protection against this virus. This has been observed already in experimental studies that showed cattle vaccinated against BVDV had no protection against Hobi-like pestivirus infection. Thus, it is of paramount importance to pay attention to this virus to prevent introduction into the U.S., and in this way protect the nation’s cattle population from economic impact. To achieve this, continuing surveillance is required along with biosecurity, adequate diagnostic tests and effective vaccines.
What are the risk factors for entry of this virus into the U.S.?
The main risk factors for the entry of Hobi-like pestivirus into the U.S. are by contaminated biological products from fetal calf serum such as vaccines. Other sources, including semen, embryos or imported animals from countries which possess this virus, are all potential risk factors for transmission. As some current diagnostic assays are not able to detect this virus, it can be introduced in the U.S. and spread to a large region of the country before it is identified. Thereby, it may compromise animal health, control programs and lead to large economic losses. Recent studies have shown the VetMAX-Gold BVDV PI Detection Kit can detect Hobi-like pestivirus in field samples from Brazilian cattle where the virus is likely endemic.
Simone Silveira is a Ph.D. Student, Virology Laboratory, Federal University of Rio Grande do Sul (UFRGS) – Brazil.