ABSTRACT
Despite significant economic losses resulting from infection with Anaplasma marginale, a tick-transmitted rickettsial pathogen of cattle, available vaccines provide, at best, only partial protection against clinical disease. The green-fluorescent protein expressing mutant of the A. marginale St. Maries strain is a live, marked vaccine candidate (AmStM-GFP). To test whether AmStM-GFP is safe and provides clinical protection, a group of calves was vaccinated, and clinical parameters, including percent parasitized erythrocytes (PPE), packed cell volume (PCV) and days required to reach peak bacteremia, were measured following inoculation and following tick challenge with wild type St. Maries strain (AmStM). These clinical parameters were compared to those obtained during infection with the A. marginale subsp. centrale vaccine strain (A. centrale) or wild type AmStM. AmStM-GFP resulted in similar clinical parameters to A. centrale, but had a lower maximum PPE, smaller drop in PCV and took longer to reach peak bacteremia than wild type AmStM. AmStM-GFP provided clinical protection, yielding a stable PCV and low bacteremia following challenge, whereas A. centrale only afforded partial clinical protection.
Subject(s)
Anaplasma marginale/immunology , Anaplasmosis/immunology , Cattle Diseases/immunology , Rickettsial Vaccines/immunology , Vaccination/veterinary , Anaplasma marginale/genetics , Anaplasmosis/microbiology , Anaplasmosis/prevention & control , Animals , Antibodies, Bacterial/blood , Bacteremia/microbiology , Cattle , Cattle Diseases/prevention & control , Cross Protection/immunology , Erythrocytes/microbiology , Green Fluorescent Proteins/genetics , Male , Rickettsial Vaccines/adverse effectsABSTRACT
The article substantiates epidemiological expediency of complex (associated) immunization of servicemen and population against typhoid, typhus and plague in polyetiological zones of these infections, and also in cases of simultaneous proliferation of these diseases. For simultaneous preventive vaccination against these infections a complex immunization scheme was experimentally substantiated and clinically approved. It is based on national commercial vaccines and ensures a simultaneous administration of 2-3 vaccine preparations by hypodermic syringe or jet injection. Typhoid and typhus vaccines are injected under one shoulder-blade, and plague vaccine is injected under another shoulder-blade. This complex vaccine is harmless, moderately reactogenic, develops expressing immunity which have the same protective features as monovaccines alone. This scheme is recommended for use in anti-epidemic practice.
