Title: BVD: Information on Type 2 virus (11/94)
Document-date: November 1994
Author: S. Bolin & J. Ridpath, USDA-ARS, NADC
INFORMATION ON BVD Virus-Type 2
Bovine viral diarrhea virus is now segregated into two genotypes, BVDV type 1 and BDVD type 2. Type 1 BVDV include vaccine and laboratory reference viruses BVDV-NADL, BVDV- Singer, BVDV-C24V, and BVDV-NY1. Type 2 BVDV are not yet commonly used for laboratory diagnostic purposes or for vaccines. The good news is that the viral genotypes share some antigenic determinants. Antibody raised against BVDV-1 will neutralize infectivity of BVDV-2; however, the efficiency of viral neutralization is less. This means that current diagnostic reagents can detect BVDV-2 and current vaccines will stimulate cross-reactive antibody that should offer some protection from disease.
Most isolates of BVDV-2 are noncytopathic in cell culture, but cytopathic BVDV-2 exist. The range of clinical disease associated with BVDV-2 is similar to that of BVDV-1. Some isolates of BVDV-2 have come from herds with subclinical to mild disease. Persistently infected cattle and mucosal disease occur with BVDV-2. Abortions and other signs of reproductive failure occur with BVDV-2. Also, there are some exceptionally virulent BVDV-2 that induce severe disease processes which include thrombocytopenia and hemorrhagic syndrome, high fevers and sudden death (peracute BVD), and enteric disease with lesions similar to those of mucosal disease. Thus, the BVDV-2 appear to be a group of viruses whose members vary in virulence.
The virulent BVDV-2 have caused substantial losses to individuals producers and have spread among neighboring farms to cause substantial losses over geographic areas. At this time, there is need to establish, both the geographic distribution of BVDV-2 and the impact these BVDV have on beef and dairy production. Outbreaks of acute BVD that are unusually severe clinically, or are mild clinically but have an unusually high morbidity, are of interest. Currently, serologic based diagnostic tests can not differentiate viral type; therefore, a viral isolation from these outbreaks is important to type the BVDV involved. The typing procedure is expensive and time consuming, so there is a need to limit use of this procedure. It is best to work closely with state and federal diagnostic laboratories in selection of viruses for typing.
For more information please contact:
Centers for Epidemiology and Animal Health
APHIS:VS:CEAH Attn: NAHMS
2150 Centre Ave., Bldg. B, MS 2E7
Fort Collins, CO 80526-8117