March 2016

Associate Photo
Mark Rooney
Director, US Swine Business Unit
Dear Subscriber: Welcome to Phibro ProSM, a newsletter for professionals in the swine production industry. Six to eight times a year, we will send you this e-newsletter with helpful information designed to help improve your business.

MJPRRS® Technology: Immune Response

In previous editions, MJPRRS Grouping Technology and vaccine preparation differences were introduced. Comparisons were made using an actual farm example and methods of differentiating mutations versus new viral introductions. Since no vaccine produced with a single isolate is capable of protecting against all PRRS viruses, a further attempt to explain why animals respond differently to each PRRS virus is needed.

Using the attached graphic, this variation in both pig-to-pig response and to variations in virus preparation will be explained with Western blot analysis. Pigs 1 and 2 have been vaccinated with a killed vaccine prepared with viruses 1, 2, 3, & 4 in a conventional manner. Pig 3 received the same viruses in a vaccine prepared via MJPRRS technology. Immune responses from Pig 1 and 2 would have been expected to have a higher N-protein response predominantly, (See previous edition “Taking a Fresh Look at PRRS”). A similar N-protein response might be expected from Pig 3, but higher E-protein response would be anticipated from the MJPRRS preparation method. Darker and wider bands equate to more intense antibody response to a particular protein.

Click here to view the full-sized chart.

Differences between Pig 1 & 2 demonstrate pig-to-pig variation in immune response even with the same antigens being presented in the exact same manner. Pig 1 shows response to N-protein antigens and poor response to E-protein antigens. This animal responded very poorly to virus 3 on all accounts, but may have responded to more than one component of the presented N-proteins of viruses 1, 2 and 4. Pig 2 shows that this animal responded a little more intensively. Several N-protein bands are starting to develop in response to viruses 1, 2 and 4, and there is minor E-protein response as well. Keep in mind that these two animals received the same vaccine containing the same 4 virus isolates.

Compare Pigs 1 and 2 to the response elicited by Pig 3. Not only did this animal produce a similar or more intense response to the N-proteins than Pigs 1 & 2, but further definition of response is noted with extra bands being identified from Pig 3. Virus 3 produced very little response from either of the first two animals, but not only are there 2 easily identified N-protein bands, but also a response to the E-protein of this virus (the other two animals had very poor E-protein response). Pig 3 also demonstrates a variety of E-protein response where only a single band if any is identifiable from Pig 1 or 2.

To take this a step further, if E-proteins aid the virus in identifying a potential host cell, what would it mean if antibodies could be produced against E-proteins?

N-proteins are great stimulators of an immune response, but as discussed in a previous communication, these proteins are non-specific and are better at describing prior exposure than they are at providing protection. E-protein, with one of its functions being to identify a suitable host cell, is found on the surface of an intact virus particle; N-protein is not. N-protein is covered by a membrane until it is uncoated upon entering the host cell; the pig’s immune system, no matter the number of antibodies to this, is not able to see this protein with an intact virus particle. Notice the E-Protein response by Pig #3. The response is intensified as shown by this Western Blot relative to conventional killed presentations (pig #1 & pig #2).

Small changes occurring in critical areas of the virus ORF 5 sequence can have very profound effects on the virus’ ability to cause repeated clinical signs. Changes in E-protein by mutation allows the virus to escape the most recent host immune response. Proper immune recognition and an understanding of common viral group mutations, are fundamental components of MJPRRS Grouping and vaccine preparation technologies.

A future edition will provide a comparative insight on the 1-7-4 apparent PRRS epidemic. As has been discussed to this point, PRRS viruses are not created equal and are not responded to equally by all individual animals. Why has this 1-7-4 virus been so problematic and has this truly been a single virus (immune presentation) epidemic?

If you have additional questions regarding the application of this technology for your client farms or systems, please contact your Phibro representative.


Potency and efficacy of autogenous biologics have not been established.
MJPRRS Autogenous Vaccines manufactured by and distributed to veterinarians by Phibro Animal Health Corporation.


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