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.

Your Farm has 1-7-4, Now What?

Since late 2013 an epidemic has been sweeping the US swine industry. Known as 1-7-4 PRRS viruses, they have been recognized as such in many recent discussions (National Hog Farmer, 2015 Allen D. Leman Swine Conference, and the 2015 American Association of Swine Veterinarians Conference). Challenges still exist related to characterizing why this particular RFLP pattern has been so prevalent as well as why so many farms have been re-infected. None of the current comparative diagnostic tools have completely explained the clinical differences amongst farms or the true nature of this epidemic across North America.

The assumption has been that all 1-7-4 PRRS viruses are created equal. This assumption is incorrect! Some are created equal, but others are quite different and would be expected to behave as such as shown by using the MJPRRS® Grouping Technology, (see previous editions).

Using the MJPRRS®Grouping Technology database, ~80% of 1-7-4 PRRS viruses have been categorized as group D-7 viruses. Several questions may come to mind:

  1. Which MJPRRS® groups are the other 1-7-4 PRRS viruses identified as?
  2. Would they be capable of producing a different clinical presentation?
  3. Can D-7 viruses be associated with other RFLP patterns?

Which MJPRRS® groups are the other 1-7-4 viruses identified as?

So far, besides the D-7 group, there have been three other MJPRRS® groups identified: D-2, D-4, and D-6. The D-4 and the D-6 have been more commonly identified as the second and third options bearing the 1-7-4 RFLP.

Would they be capable of producing a different clinical presentation?

Recalling several of the previous newsletter articles in this series, changes in immunological presentations (MJPRRS® groups) would be expected to have clinical signs associated with these changes. With this knowledge, it is more easily understood how a single 1-7-4 infection followed by a second 1-7-4 infection could be of varied clinical signs. For example, a farm may have had a D-7 (1-7-4) virus originally, and via mutation or independent virus introduction, a second infection would be observed clinically if the new identification was a D-6 (1-7-4) virus.

Can D-7 viruses be associated with other RFLP patterns?

The short answer to this question is yes. The D-7 group has been identified with PRRS viruses having RFLP patterns of 1-4-4, 1-7-3, 1-7-2, 1-18-2, 1-10-4, 1-21-4 among others. Utilizing only RFLP as the method of naming and epidemiologically following the virus through farms, regions and across the country may lead to incorrect conclusions. In fact, this apparent 1-7-4 epidemic may be better classified as a D-7 group epidemic.

Since March of 2015, 30% or more (range 30 – 50%) of the monthly MJPRRS® groupings analyzed have been identified as a D-7 group virus. This is not merely the average of 12 months accumulated data; this is a month over month identification of PRRS virus ORF5 sequences analyzed since early 2015. See the attached chart or monthly D- and S-group percentages.

Most if not all of these D-7 virus identifications from March 2015 thru October 2015 have been associated with a new PRRS break on these farms. In other words, the resident farm virus had been something other than a D-7 prior to the D-7 being identified. As can be gathered from the other discussion points in this article, it should not be a surprise that these D-7 identifications were not all 1-7-4 RFLP pattern. Of all the D-7 viruses identified, roughly 60% would also have been a 1-7-4, but 40% have been associated with other RFLP patterns.

Although the 1-7-4 nomenclature has not been consistent, this D-7 virus has dominated the scenery across the US for the last 24 months. New identifications are still being recorded today. Evaluation of the MJPRRS® grouping incidence over the last 10 years may shed light as to the spread of this D-7 virus. The following chart shows a very low prevalence of D-7 virus in the North American swine herd leading up to 2013 – compare this to D-4, D-5, and D-6 presentations prior to 2013. This sudden increase in D-7 identification and subsequent decrease in other groups identified by the MJPRRS® technology points towards an epidemic becoming endemic. Although the 1-7-4 designation has captured many of the widespread PRRS breaks over the last two years, other participants in this epidemic have been excluded because the virus RFLP was not 1-7-4. MJPRRS® Grouping Technology not only explains the underlying devastation of the D-7 immunological presentation, but also explains why farms could experience multiple PRRS breaks with the 1-7-4 virus. Maybe it is worth taking a look at the 1-7-4 virus your client’s farm or system may be dealing with – not all are created equal.

MJ Biologics utilizes this unique grouping technology for PRRS viruses and vaccine production methods to create a Tailor-made® vaccine for your system.

For additional information please contact your Phibro Animal Health representative.

Click here to view the full-sized charts.


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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