the first three to four months of gestation, then it will fail to develop antibodies towards the virus. In these cases, the animals often die before birth or shortly after. It is spread very easily among feedlot cattle as nasal secretions and close contact spread the disease, and animals with infected mucous membranes give off millions of particles of BVDV a day. Symptoms of Pestivirus infection include diarrhoea, respiratory problems, and bleeding disorders. Pestivirus A vaccines exist and the correct vaccine strain should be given, depending on the herd's location and the endemic strain in that region. This vaccination must be given regularly to maintain immunity. Vaccines There are 120 registered BVD vaccine products currently used around the world, mainly in North and South America. These are conventional modified live virus (MLV) or inactivated/killed virus vaccines. In pregnant animals live vaccines pose significant risk of vertical transmission of vaccine virus that can occasionally result in complications for calves. Most of the harm done by BVDV is to unborn calves and depends on the timing of infection. Vaccination has not proved to be effective for Bovine Viral Diarrhea (BVD), as the presence of BVD has not lessened since the vaccine has been developed. Animals who are affected by the virus during early fetal development may become persistently infected (PI) and lack an immune response to BVD. These animal’s presence in herds and them shedding virus can infect other animals in the herd before vaccination is possible. PI animals do not produce antibodies and are the main source of infection for herds, so culling is necessary to eradicate infection sources. Vaccines are not able to prevent fetal infections, so this poses a huge source of infection for cattle herds. Another reason for the inefficiency of the BVD vaccine is because of failure to vaccinate whole areas, rather than just individual herds. Border Disease, which affects lambs, is also caused by Pestivirus, but has no vaccine at this time. Marker vaccines are beneficial tools for the eradication of animal diseases in regions with a high prevalence of the designated disease. The chimeric CP7_E2alf used to see how altered cell tropism affects pigs may not only serve as a tool for a better understanding of Pestivirus attachment, entry, and assembly, but also represent modified live CSFV "marker vaccines." Structural and non-structural proteins Genomic RNA of pestiviruses is translated into a large polyprotein that is