Methods and vaccines for providing in OVO protection against turkey rhinotracheitis

Abstract

Methods and compositions for protecting avian hosts (e.g., turkeys and/or chickens) from turkey rhinotracheitis virus and/or TRT or SHS respiratory distress utilize in ovo administration of live, avirulent strains of TRTV at appropriate dosage levels on a per egg basis to provide an effective and efficient vaccination having acceptable safety and efficacy features, and additionally provides higher titers in vaccinated birds than conventionally administered vaccines.

What is claimed is:  
     
         1 . A method for protecting an avian host from TRT and/or TRT or SHS-related respiratory distress comprising administering a vaccine in ovo to a fertile egg containing an embryo of the avian host, said vaccine comprising an immunogenically-effective amount of a live, attenuated strain of turkey rhinotracheitis virus in the approximate range of from about 10 3.2  TCID 50  per egg to about 10 4.5  TCID 50  per egg, wherein said vaccine is administered on or before day 24 of incubation.  
     
     
         2 . The method of  claim 1 , wherein said immunogenically-effective amount is administered in a suitable vehicle of approximately 0.05 to 0.1 ml per egg.  
     
     
         3 . The method of  claim 2 , wherein the immunogenically-effective amount is about 10 3.2  TCID 50  per egg.  
     
     
         4 . The method of  claim 2 , wherein the immunogenically-effective amount is about 10 4.2  TCID 50  per egg.  
     
     
         5 . The method of  claim 1 , wherein said avian host is a turkey or chicken embryo.  
     
     
         6 . The method of  claim 5 , wherein said administration occurs on approximately day 18 of incubation (chicken) or approximately day 24 of incubation (turkey).  
     
     
         7 . The method of  claim 3 , wherein the avian host is either a turkey or a chicken embryo.  
     
     
         8 . The method of  claim 7 , wherein the avian host is a turkey embryo.  
     
     
         9 . The method of  claim 7 , wherein the avian host is a chicken embryo.  
     
     
         10 . A process for protecting turkeys and chickens from exposure to virulent strains of turkey rhinotracheitis virus, comprising administering in ovo to fertile eggs a vaccine comprising, on a per egg basis, an immunogenically-effective amount of a live, avirulent strain of turkey rhinotracheitis virus, wherein said administration results in a decrease in the percentage of eggs that hatch of less than about 2%.  
     
     
         11 . The process of  claim 10 , wherein the immunogenically-effective amount is in the approximate range of from about 10 3.2  TCID 50  per egg to about 10 4.2  TCID 50  per egg.  
     
     
         12 . An in ovo vaccine for protecting turkeys and/or chickens from exposure to virulent turkey rhinotracheitis virus, comprising a buffered solution containing, on a per egg basis, a live, attenuated strain of turkey rhinotracheitis virus in an immunogenically-effective amount of from about about 10 3.2  TCID 50  to about 10 4.2  TCID 50 .  
     
     
         13 . The vaccine of  claim 11 , wherein the immunogenically-effective amount is efficacious against subsequent post-hatch exposure of the turkey an/or the chicken to virulent turkey rhinotracheitis virus; and produces substantially no decrease in the percentage of in ovo vaccinated turkey and/or chicken eggs that hatch upon the expiration of the incubation period.  
     
     
         14 . The vaccine of  claim 13 , wherein the immunogenically-effective amount is about 10 4.2  TCID 50 .  
     
     
         15 . A method for inoculating poultry against turkey rhinotrachetis disease which comprises administering an immunologically effective amount of a live, attenuated strain of TRT virus in a pharmaceutically acceptable carrier in ovo within the range of at least about 10 3.2  TCID 50  per egg to about 10 4.2  TCID 50  per egg.  
     
     
         16 . The method of  claim 15 , which further comprises administering together with said TRT at least one other vaccine selected from the group consisting of Newcastle Disease vaccine, and infectious bursal disease vaccine.  
     
     
         17 . The method of  claim 16 , further comprising administering at least one vaccine selected from the group consisting of infectious bronchitis vaccine and Marek's disease vaccine, wherein said vaccine is administered post-in ovo.  
     
     
         18 . The method of  claim 17 , wherein said post-in ovo vaccine is administered at approximately day 1 of age.  
     
     
         19 . The method of  claim 15 , wherein said method results in substantially no decrease in the number of eggs that hatch.  
     
     
         20 . The method of  claim 15 , wherein said method produces a decrease in the percentage of eggs that hatch of less than about 5%.  
     
     
         21 . The method of  claim 21 , wherein said method produces a decrease in the percentage of eggs that hatch of less than about 1%.  
     
     
         22 . A method of providing elevated titers to TRTV, which comprises formulating an in ovo vaccine of attenuated TRTV antigen, and administering said vaccine so as to provide a TCID 50  in the range of about 10 3.2  to about 10 4.5  per egg within a vehicle of approximately 0.05 to 0.1 mL per egg.