Points of Interest
Note: Too bad we sacrificed those thousands upon thousands of healthy asymptomatic horses in a misguided attempt to eradicate or control an infection that was not properly understood. From now on we should be concentrating on preserving the genetics of the horses whose immune systems are able naturally to control repeated attacks of this virus for which we have no artificial immunization or treatment available.
Selection of a Rare Neutralization-Resistant Variant following Passive Transfer of Convalescent Immune Plasma in Equine Infectious Anemia Virus-Challenged SCID Horses
Sandra D. Taylor,1 Steven R. Leib,1 Susan Carpenter,1,2 and Robert H. Mealey1* "Plasma containing antibodies from a long-term asymptomatic horse prevented clinical disease in 3 of 4 SCID foals when challenged with 1 homologous and 5 heterologous strains of EAIV. In the 4th foal infection was prevented completely."
Quoted from: Dr’s. Jodi K. Craigo and Ronald C. Montelaro from their report in the Journal of Virology entitled : EQUINE INFECTIOUS ANEMIA VIRUS INFECTION AND IMMUNITY: LESSONS FOR AIDS VACCINE DEVELOPMENT
“Importantly, natural inapparent carriers are remarkably resistant to frequent exposure of variant EIAV strains that are transmitted by horsefly bites in the field. Thus, EIAV uniquely offers a natural model for the immunologic control of a lentivirus infection and disease, and the virus-specific immune responses present in inapparent carriers appears to offer the enduring broadly protective immunity against virus exposure that has been the elusive goal of AIDS vaccine research for the past 30 years.”
Personal comment here: If we understand the current literature correctly, it would appear that the researchers are still struggling to understand exactly how a horse’s immune system reacts so as to withstand the challenge of an EIAV infection. Interesting that 40 years ago our governing bodies felt they knew enough about it to embark upon a test and slaughter program promoted to eradicate the disease in the US and Canada. When it became obvious that eradication was impossible by that method, against the advice of the majority of researchers and in the face of massive public opposition, they pressed blindly onward. Only now they called it a control program.
Many thousands of horses have been sacrificed causing extreme emotional distress and in many cases tremendous financial hardship.
Over the course of time it has often been suggested that perhaps a valuable lesson could be learned from the fact that foals nursing Coggins positive mares carried maternal antibodies in their bloodstream and virtually never became infected with EIAV. It has also been suggested many times that perhaps asymptomatic Coggins positive horses might possibly maintain some immunity to future infections. Whenever we suggested this to our regulatory people, they flatly denied the possibility on the grounds that since a lentivirus was capable of mutating, the horse’s immune system would not be able to recognize the new identity, the antibodies it carried would be of no use, and therefore the horse would become re-infected.
It would appear from the research in the last ten years that time and money would have been better spent studying the asymptomatic horses rather than destroying them. Or if no one was interested in studying them, at least let them live and pass on their genetics to future generations. If we are determined not to control this virus by artificial means, then we should perhaps step out of the way and let nature control it as was the case in the previous five hundred or more years.
|
