Equine Rhinopneumonitis Virus

A process for the production of immunogenically active attenuated live equine rhinopneumonitis virus which comprises the steps of:

• (a) introducing a live virulent equine rhinopneumonitis virus into a monolayer of a Vero permanent cell line;
• (b) incubating the culture from about 3 to about 5 days at a temperature of 37.degree. C. until cytopathology of the cells is substantially complete;
• (c) harvesting a portion of the virus so produced and introducing the harvested virus into a freshly prepared stable cell monolayer of Vero cells.
• (d) incubating said culture at a temperature of about 26.degree. C. for a period of time sufficient to result in cytopathology of at least a portion of the tissue cells;
• (e) serially passing a portion of the virus so produced in stable vero cells at least 45 times at an incubation temperature of about 26.degree. C. to produce an immunogenically active live avirulent virus;
• and
• (f) recovering said virus from said last serial passage.

An attenuated live equine rhinopneumonitis virus vaccine containing an effective quantity of immunogenically active avirulent live equine herpes I virus produced by a process which comprises the steps of:

• (a) introducing a live virulent equine herpes I virus into a Vero cell culture;
• (b) incubating the culture until the cellular cytopathology becomes evident;
• (c) harvesting a portion of the virus so produced and re-introducing the harvested virus into fresh tissue culture;
• (d) repeating serial passage of the virus in tissue culture a sufficient number of times at a temperature within the range of from about 23.degree. to about 33.degree. C. to produce an immunogenically active live avirulent virus.
• (e) recovering said virus from said tissue culture medium;
• and
• (f) adding said recovered virus to a stabilizing solution to form a vaccine therefrom.

An attenuated live equine rhinopneumonitis virus vaccine containing an effective quantity of immunogenically active avirulent live equine rhinopneumonitis virus produced by a process which comprises the steps of:

• (a) introducing a live virulent equine rhinopneumonitis virus into a monolayer of a Vero permanent cell line;
• (b) incubating the culture from about 3 to about 5 days at a temperature of 37.degree. C until cytopathology of the cells is substantially complete;
• (c) harvesting a portion of the virus so produced and introducing the harvested virus into a freshly prepared stable cell monolayer of Vero cells
• (d) incubating said culture at a temperature of about 26.degree. C. for a period of time sufficient to result in cytopathology of at least a portion of the tissue cells;
• (e) serially passing a portion of the virus so produced in stable Vero cells at least 45 times at an incubation temperature of about 26.degree. C. to produce an immunogenically active live avirulent virus;
• and
• (f) recovering said virus from said last serial passage.

The method of protecting members of the family Equidae from equine rhinopneunominitis virus infection which comprises administering to said horses an effective dose of a live attenuated ERP virus vaccine prepared by a process which comprises the steps of:

• (a) introducing a live virulent ERP virus into a Vero cell culture;
• (b) incubating the culture until the cellular cytopathology becomes evident;
• (c) harvesting a portion of the virus so produced and reintroducing the harvested virus into fresh tissue culture;
• (d) repeating serial passage of the virus in tissue culture a sufficient number of times at a temperature within the range of about 23.degree. to about 33.degree. C. to produce an immunogenically active avirulent virus;
• and
• (e) recovering said virus from said tissue culture medium.

The method of protecting equines from ERP virus infection which comprises administering to said equines an effective dose of a live attenuated ERP virus vaccine prepared by a process which comprises the steps of:

• (a) introducing a live virulent ERP virulent ERP virus into a monolayer of a tissue cell culture derived from Vero cells;
• (b) incubating the culture from about 3 to about 5 days at a temperature of 35.degree. C. until cytopathology of the cells is substantially completed;
• (c) harvesting a portion of the virus so produced and introducing the harvested virus into a freshly prepared monolayer of Vero cells.
• (d) incubating said culture at a temperature of about 26.degree. C. for a period of time sufficient to result in cytopathology of at least a portion of the cells;
• (e) serially passing a portion of the virus so produced in Vero cells at least fifty times at an incubation temperature of about 26.degree. C. to produce an immunogenically active live avirulent virus;
• and
• (f) recovering said virus from said last serial passage.