1 Update on Ovine Progressive Pneumonia Virus Control Holly Neaton DVM Minnesota Veterinary Medical Association Annual Meeting February 6, 2014
2 Renewed Interest in OPPV/MVV Ovine Progressive Pneumonia Virus = Maedi Visna Virus NAHMS studies have shown 36% of flocks and 24% of sheep tested in USA are infected USDA Meat Animal Research Center (MARC) in Clay Center, Nebraska has found genetic influences leading to a genotyping test for susceptibility to the OPPV MARC scientists have also found horizontal adult transmission more a factor in transmission of the virus than dam to lamb via colostrum/milk
3 OPPV Facts No vaccine available Lives in white blood cells Only survives outside of the sheep for several minutes OPPV in the same virus family as HIV Positive tests without signs Causes reduced milk supply (hardbag), pneumonia, wasting, lameness No treatment
4 Genetic Susceptibility Factor Think of scrapie genotyping RR, QR, QQ R gene is dominant and incurs resistance TMEM154 OPP influencing gene (one from dam and one from sire) are numbered 1,2,3,4,10 etc with 1,2,3 being most common 2,3 most susceptible to being infected and affected by the OPPV 1,4,10 are the genes that are desirable to decrease susceptibility to virus (4 and 10 are rare) 1 is recessive so would really like 1,1 genotype http://www.ars.usda.gov/sp2userfiles/place/54380000/ OPP%20Handout.pdf (OPP gene MARC)
5 Genetic Influence! Stress, poor management can override the genotype influence! This new research could partially explain why some breeds/flocks are more susceptible to the virus than others Are the flocks that are devastated by clinical effects of the OPPV genetically challenged? Would adding TMEM154 1,1 genes decrease the clinical signs?
6 Transmission of OPPV This finding is really exciting for producers who want to eradicate OPPV Historically we thought the virus infected lambs at birth via colostrum and dam s milk So control was aimed at preventing lambs from maternal contact Actually maternal antibodies in colostrum and milk may protect lambs from infection
7 Old Control Strategy One or all of below: Be present at birth and snatch lambs to be raised as orphans and then raised as separate flock need artificial colostrum and lots of milk replacer Test entire flock annually, cull positives or keep negatives as separate flock Expensive, frustrating (who can be present at every birth?), not always successful, took years
8 New Control Strategy Suggest to test adults (or statistical portion of) to determine infection rate. Test replacement ewe lambs at 6-10 mos and cull positives Keep negative replacements at least 10 ft from adult flock Continue to test replacement flock annually with new replacement ewe lambs and cull positives Use rams with TMEM154 genotype of 1,1 (or better) if possible
9 New Control Strategy continued - Only have to test adult flock or portion of one time. Culling is up to producer depending on genetics, feed costs, income flow. Depending on management this system may control other diseases: CL, Johnes that hang in the environment. Remember, OPPV lives in the blood. Needles, taggers, drenchers etc should be kept separate or sanitized between groups
What does Separate Flocks mean? OPPV only lives outside of sheep for several minutes Coughed particles and phlegm are most likely cause of virus transmission 10 ft has been recommended solid wall (think plywood or even pallets) or electronet are other possible barriers. Shared waterers seem to be a low risk due to the heavy phlegm falling to bottom of trough No shared feeders 10
11 Don t let the SEPARATION requirement scare you off! Yes - the test negative replacement ewe lambs become ewes and need to be kept from the original infected flock. Even keeping them in a separate pen is better than commingling. If the theory plays out using genetically less susceptible rams will help the replacement flock stay negative
12 Testing for OPPV Test for antibodies in blood determines exposure to virus Draw blood, let red blood cells clot and use serum to send to the lab Tests available have been tricky to use most reliable (AGID) also the least sensitive (false negatives due to low antibody levels from new infection or heavy colostrum level) ELISA so sensitive it gives false positives
13 Agar Gel ImmunoDiffusion test AGID: hard to read so technician error is possible. Only ~75% sensitive but ~100% specific with trained technician Has been the best test thus far though not perfect
14 Enzyme Linked Immunosorbent Assay VMRD s celisa - designed for goat CAEV but is being used and is now USDA-licensed for sheep OPPV Easy to use in any technician s lab Super sensitive so may give false positives due to other antibody influences My personal opinion is to not use it due to inaccuracies
15 New test available ELITEST an ELISA test built on early work at MARC and developed in Scotland. Licensed and used in Europe and Canada Considered the most reliable and accurate test by Canadian experts (also is the only ELISA for SRLVs to have been validated by OIE standards) Currently not licensed in the US but available at the Minnesota Veterinary Diagnostic Lab Price comparable to AGID and celisa ~ $6
16 Three New Tools 1. Genetic susceptibility using 1,1 or better rams to add 1 genes to offspring GeneSeek in Lincoln, NE performs test on bloodspot cards or purple top edta tubes for $12 website 2. Prevent adult to adult transmission (wean ASAP to prevent adult to lamb respiratory transmission) no more snatching lambs from dams at birth and raising as orphans 3. ELITEST reliable new blood test to detect positives
17 OPP Eradication Trial Voluntary OPP and CAE Test and Control Pilot Program has been available to MN producers for 7 years. It is supported by the MN Board of Animal Health and was originally linked to the Voluntary Scrapie Flock Certification Program which is becoming more restrictive; OPP Pilot continues and is now open to anyone). Summer of 2013: USDA DVMs suggested that this program be continued as the USDA would like to keep a presence on sheep farms. They recognized OPP s economic impact and revealed that USDA funds are no longer restricted to scrapie) Due to the new research findings, we suggested adding an eradication trial using this new information
18 Trial continued More producers might be interested in joining this trial as it will not be tied to the SFCP The MN VDL agreed to lower price to $4 per test and support the program using the ELITEST The MLWP voted in September to contribute $2 per test and $12 for a genetic test for a ram per 25 ewes USDA and MN Board of Animal Health agreed to use their field staff to collect samples and verify inventory
19 Producer s responsibilities Fill out application form only the 10-12 most heavily infected flocks will be accepted for the trial Contact your veterinarian a letter for explanation will be sent to them also once your application form is received Maintain a flock inventory in a provided Excel (or similar)spreadsheet and submit annual updates After the first year only the replacement flock needs to be inventoried The participating producer agrees to pay $2 per head tested, provide sampling equipment (needles, tubes, syringes) and bring the filled tubes to their veterinarian who will prepare them and mail them to the MN VDL
Producer s responsibilities continued 20 Have adequate help and facilities for field staff Bring filled tubes to flock DVM along with completed forms Genetic tests can be mailed directly by producer who will be reimbursed by MLWP (1 per 25 ewes) Wait for test results and remove positive ewe lambs, keeping negative replacement ewe lambs as a separate flock
21 Three Years? Program has been organized quickly to be able to test 2013 s ewe lambs Year 2 - test replacement flock again and new replacement ewe lambs Length of program is considered to be 3 years depending on results and how much money we all have
22 No Guarantees!! There are no guarantees this program will work although the research is sound and it is exciting to be involved in something that may change the way this disease is viewed! If you are interested please contact : Judy Lewman lewman@frontier.com or 952-472-4524 Holly Neaton hollyneat@juno.com or 952-240- 2192
23 OPP Pilot/Eradication Trial working group James Baglien*, purebred producer (OR) Randall C. Cutlip*, Research Leader (retired), USDA-ARS-National Animal Disease Center (IA) Clark BreDahl*, purebred and commercial producer, columnist for 'The Shepherd' magazine (IA) James E Collins, Director, Minnesota Veterinary Diagnostic Laboratory (MN) Bill Duffield*, purebred producer (ON, Canada) John Dvorak, commercial producer, President, MN Lamb & Wool Producers Association (MN) Charles N Gaiser, Eastern Regional Epidemiologist, USDA-APHIS-VS (NC) Linda Glaser, Senior Veterinarian, MN Board of Animal Health (MN) Michael P Heaton, Molecular Geneticist, USDA-ARS-Meat Animal Research Center (NE) Lynn M. Herrmann-Hoesing, Research Microbiologist, (formerly) USDA-ARS-Animal Disease Research Unit (WA) Steven D. Just, District Veterinarian, USDA-APHIS-Veterinary Services (MN) Cleon V. Kimberling, Extension Veterinarian (retired), Colorado State University (CO) Donald P. Knowles, Research Leader, USDA-ARS-Animal Disease Research Unit (WA) Robert Leder*, Veterinarian, commercial producer (WI) Mark Lelli*, Veterinarian, commercial & purebred producer (MI)
24 Working group continued Judy Lewman*, purebred producer (MN) Kreg Leymaster, Geneticist, USDA-ARS-Meat Animal Research Center (NE) Katherine L. Marshall, Epidemiologist, USDA-APHIS-Nat l Animal Health Monitoring System (CO) Susan L McClanahan, Senior Veterinarian, MN Board of Animal Health (MN) Holly Neaton*, Veterinarian, MN Board of Animal Health, commercial & purebred producer (MN) Kelly Neisen, CVT, National Veterinary Accreditation Program Coordinator, USDA- APHIS-VS (MN) Gene Schriefer*, commercial producer (WI) James Schultz*, commercial producer (WI) William P. Shulaw*, Extension Veterinarian (retired), The Ohio State University Susan M. Stehman, Extension Veterinarian, Animal Health Diagnostic Center, Cornell University (NY) Jean T. Walsh*, purebred producer (NY) (* designates OPP Society member)
Chart of significant RANDOM sample numbers Flock Size Sample Size Flock size Sample size 10 10 180 50 20 19 200 51 30 26 250 53 40 31 300 54 50 35 400 55 60 38 500 56 70 40 700 57 80 42 1000 58 90 43 120 47 95% confident of detecting at least 140 48 1 positive animal if 5% of flock is infected 25
26 A Big Thank You to: MN Board of Animal Health MN Veterinary Diagnostic Lab College of Veterinary Medicine Minnesota Lamb and Wool Producers
27 More OPPV information Ovine Progressive Pneumonia Concerned Sheep Breeder s Society www.oppsociety.org http://oppsociety.org/library files/leymaster_jan_2013.pdf Minnesota Board of Animal Health http://mn.gov/bah/ look at information regarding Sheep and Goats Premier website Guide to all Things Sheep: Education Reducing the Risk of OPP Infection Dr. Kreg Leymaster s power point from 2012 GENESEEK 402-435-0665 www.neogen.com/geneseek Judy Lewman lewman@frontier.com Holly Neaton hollyneat@juno.com