TSV-2® Bovine Rhinotracheitis, Parainfluenza 3 Vaccine TSV-2® is for vaccination of healthy cattle, including pregnant cows, as an aid in preventing infectious bovine rhinotracheitis caused by infectious bovine rhinotracheitis (IBR) virus and disease caused by PI3 (parainfluenza3) virus. The vaccine is prepared by growing attenuated virus strains on a bovine cell line. The virus fractions are combined and stabilized by freeze-drying. A sterile diluent is supplied for rehydration. TSV-2 is unique in that the virus strains it contains are temperature specific. Tests have shown that they will not grow in vivo at or above 39°C, the normal bovine body temperature. This restricts viral replication to the nasal mucosa, which is constantly ventilated and maintained at temperatures less than 39°C, even in the febrile animal. At this localized site, the temperature-specific viruses replicate and stimulate local and systemic immunity. Because the temperature-specific strains cannot grow in the internal body organs or developing fetus, pregnant cows may be safely vaccinated.