February 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.

Taking a Fresh Look at PRRS

Veterinarians and producers alike are all too familiar with Porcine Respiratory and Reproductive Syndrome (PRRS) virus.  Depending on the geographic location of the farm, PRRS virus infections may appear as seasonal bouts or can occur almost year-round. 

PRRS is problematic for many reasons, but one of the main issues stems from an inability to identify why genetically similar viruses behave so differently in swine populations.  Small changes to the virus can have clinical impacts on a swine population even when the animals have previously been exposed.  The diagnostic tools that have been at our disposal have not always captured the clinical aspects of the disease or “How the animal responds to the PRRS virus.”

For years, dendrograms, like the one below, have been used to highlight genetic similarity of PRRS viruses to one another.  Over time, the virus changes or mutates and new strains (variants) emerge.  In an effort to be proactive, we need to compare the virus on one farm to other viruses of concern. This tool has identified the similarities of the nucleotide sequences (DNA) of the virus’ fifth open reading frame (ORF 5) gene.  However, it has failed to explain why viruses that are located right next to one another (highly-related) on the dendrogram can present a myriad of clinical signs in the same population of pigs.

Typically, the shorter the horizontal lines between viruses on a dendrogram, the more closely related the viruses.  Close may not be good enough in this situation.  This actual farm dendrogram and arrows highlight two scenarios:

  1. Viruses immediately next to each other appear related, but yield different clinical responses in a population of animals. These viruses behave as “immunological variants.”
  2. Viruses on opposite ends of the dendrogram appear more genetically diverse, but present similar clinically (“clinical clones”) in a population of animals.

Click here to view the full size chart.

MJPRRS®, developed by MJ Biologics (MJ) and licensed to Phibro Animal Health Corporation, is a technology that can identify these differences in the PRRS virus’ physical presentation – the portions of the virus that the pig detects.  The same information that most veterinarians and producers are already collecting through PRRS viral PCR and sequencing can be used to compare these physical presentations.  Using patented MJPRRS® Grouping Technology, we at Phibro Animal Health believe that the proper immune stimulating proteins can be identified and virus movement can be better tracked throughout geographic regions.  When virus grouping is coupled with a non-traditional harvesting technique, presentation of these distinctly identified antigens assists in expanding a pig’s immune response as compared to conventional killed PRRS vaccines.

One of the main differences in antigen presentation between MJPRRS and conventional killed PRRS vaccines occurs at the ratio of Envelope (E-) protein: Nucleocapsid (N-) protein presentation.  Virus cultures harvested by traditional means to prepare a conventional killed vaccine include high levels of N-protein presented to the animal’s immune system as whole, intact virus particles.  The immune response to the N-protein reflects an exposure to PRRS virus. This is the antigen-antibody response observed in the PRRS ELISA test.  This response is fairly non-specific and the animals build a robust, but non-protective, immune response to these proteins. 

Click here to view the full size chart.

The process utilized for production of MJPRRS vaccine optimizes the E- to N-protein ratio.  While it does not eliminate the N-protein, the levels of E-protein are increased and categorized as specific to one of 25 immunological presentations (groups) of the virus identified below.  The specific identification of these immunological groups, plus the ability to select up to five distinct groups (immune presentations) for a vaccine serial, tailor the vaccine specifically to disease pressure within a system.  In contrast to production techniques used for conventional killed vaccine, this unique antigen harvest process offers a variety of antigen components to which the animals can rapidly respond with protective antibodies.  

MJPRRS virus grouping can be performed on any ORF5 gene sequence.  It is likely that a producer and their veterinarian already have this information available in some format. The results of this grouping process will be reported back as one of the following 25 PRRS groups: D-1 thru D-8 (including a D-4b), S-1 thru S-8, or E-1 thru E-8.

The D- and S-group viruses are the subset of PRRS viruses unique to North America.  To date, roughly 80 – 85% of all PRRS virus sequence evaluations have identified viruses to the D-group category.  S-grouped viruses make up the remainder of the MJ groupings (15 – 20%).  European PRRS viruses have been identified in the US, but comprise a very small percentage of MJ group identifications (0.3 – 0.5%).  

Click here to view the full size chart.

There are regional differences in the identification of D- and S-groups as some of the more hog-dense areas of the upper Midwest trend closer to a 50:50 identification rate of D-grouped: S-grouped viruses.

Future discussions will address an actual on-farm scenario of virus mutation and new viral introductions.  This will illustrate how MJPRRS Grouping Technology identified the different virus groups involved in a farm experiencing multiple PRRS breaks.  A separate discussion will also explore how the immune response elicited by the MJPRRS vaccine production process provides different antibodies compared to a conventionally produced killed PRRS vaccine.

Please contact your Phibro Animal Health representative and ask how you can have your PRRS virus grouped free of charge.


*MJPRRS Autogenous Vaccines manufactured by and distributed to veterinarians by Phibro Animal Health Corporation.

Potency and efficacy of autogenous biologics have not been established.



© 2016 Phibro Animal Health Corporation, Teaneck, NJ 07666 • Phone: 888-475-7355 • www.PhibroPro.com
Phibro, Phibro logo design and Healthy Animals. Healthy Food. Healthy World. are trademarks owned by or licensed to Phibro Animal Health Corporation or its affiliates. MJPRRS is a registered trademark of MJ Biologics, Inc.

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