Bovine Coronavirus Updates. Jeremy Schefers DVM, PhD Minnesota Veterinary Diagnostic Labortory

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1 Bovine Coronavirus Updates Jeremy Schefers DVM, PhD Minnesota Veterinary Diagnostic Labortory

2 Take-home messages 1. Serum antibody titers, from either vaccination or natural exposure, don t appear to last longer than 6 months. 2. BoCV infection appears to compromise the innate mucociliary apparatus of upper respiratory epithelium.

3 Bacterial and viral pathogens in diseased bovine lung, % 40% 42% 38% Bovine Coronavirus was detected in 25% of diseased cattle lung. 35% 30% 25% 20% 15% 25% 18% Blue bars are bacteria Red bars are viruses 10% 8% 5% 2% 1% 0% Histophilus somni Pasteurella multocida Bovine Coronavirus Mannheimia hemolytica Bovine Respiratory Syncytial Infectious Parainfluenza 3 Bovine Rhinotracheitis 3

4 Immunity 2016 BoCV Goals Detect seronegative populations Determine titers generated by vaccination Determine titers generated by natural infection Estimate decay of serum antibody titer Pathology of infection Examine extent of virus infection Determine the impact of virus on upper respiratory (head) tissues

5 Seropositive dairy cows Lactating Holstein cows developed winter dystentery in April. 11 Cows sampled in late July 2 cows = neg 5 cows = cows = cow = 640

6 Seropositive dairy calves July week-old Holstein calves fed colostrum from vaccinated dams 3 calves bled: Calf 1 = 640 Calf 2 = 320 Calf 3 = 320

7 Partially seronegative heifers August month-old Holstein heifers 5 bled: 3 = seronegative 2 = titers of 80. These calves were vaccinate with Calf Guard at birth and fed colostrum from vaccinated dams.

8 Seronegative dairy heifers July 2016 Yearling Holstein heifers 6 bled and all six seronegative for BoCV (titer <20).

9 Seronegative springing heifers July 2016 Pregnant Holstein heifers due to calve in fall 6 bled and all seronegative for BoCV (titer <20).

10 Dairy herd serological profile Sample Description Result Titer 1 Lactating Heifer "Aim" Not vacc POS Lactating Heifer 1327 Not vacc POS Lactating Heifer "Tahiti" Not vacc Neg <20 4 Lactating Heifer "Sansa" Not vacc POS Lactating Heifer "Icon" Not vacc POS Dry Cow "Now" Vacc 12/10/15 POS Dry Cow "Vegas" Vacc 12/7/2015 POS Dry Cow "Concord" Vacc 12/12/2015 POS Dry Cow "Savanna" Vacc 12/6/2015 Neg <20 10 Dry Cow "Claret" Vacc 12/15/2015 POS Dry Cow "Motor" Vacc 12/8/2015 POS Newborn calf 4 POS Newborn calf 5 POS Newborn calf 6 POS month-old heifer Neg < month-old heifer POS month-old heifer Neg < month-old steer POS month-old steer Neg <20 20 Yearling heifer 1364 lot 1 Neg <20 21 Yearling heifer 1365 lot 1 Neg <20 22 Yearling heifer 1367 lot 1 Neg <20 23 Yearling heifer 1368 lot 1 Neg <20 24 Yearling heifer 1369 lot 1 Neg <20 25 Yearling heifer 1371 lot 1 Neg <20 Lactating cows: Exposed, diseased, titer mean of 160, 3 months post winter dysentery 3 newborn calves: Colostral antibody titers > 320. Heifers >6 months: Antibody titers decay away by 6 months and cattle remain negative over summer.

11 BoCV titers in two large dairy herds October 2016 Holstein cows developed winter dystentery & respiratory disease every winter. Vaccinated with killed BoCV scour vaccine at dry off. Herd 1 (n=12) 5 = Negative 2 = 80 5 = 160 Herd 2 (n=8) 2 = Negative 2 = 40 2 = 80 2 = 160

12 Seronegative cows in vaccinated, lactating dairy herds. Oct 2016 By fall, 25 42% of cows in 2 herds were seronegative for BoCV. It appears that is enough naïve cows to compromise herd immunity. Most of those cattle are more than 120 DIM (6+ months from dry cow vacc.) and less than 220 DCC (dry off). In the fall, one farm vaccinated (IM MLV) all cows 120+ DIM and less that 220 DCC. To date, there have been no episodes of winter dysentery or widespread respiratory disease.

13 Seronegative beef calves July month-old Angus calves 6 bled: All seronegative Neither the calves or dams are vaccinated for BoCV

14 Pasture behavior considerations Comfortable and content cattle spread out. Nose-tonose contact is limited. Uncomfortable cattle concentrate under trees and at water source to alleviate heat & fight flies. Risk for pathogen shedding and transmission among naïve calves is increased.

15 IM vaccinated at 1 & 5 weeks with MLV BoCV while in calf hutches. 6 calves sampled: All 6 had titers of month-old dairy steers July 2016

16 Do serum antibody titers matter?

17 BoCV antibody titer 1200 Day 5 BoCV Ab titer of fatal pneumonia cases and asymptomatic cohorts (Storz, Journal of Clinical Microbiology, 2000) Red circles = Mortalities These cattle died and had very low / absent BCoV antibody titers on day 5 Asymptomatic = These cattle were 18 normal controls that had titers, remained clinically healthy, and did not nasally shed BCoV Fatality Asymptomatic Animal

18 BoCV in a feedlot (Hasoksuz, JVDI, 2002) Ohio Feedlot Study Peak of BoCV nasal and fecal shedding occurred at 4 days post arrival Day 1: 11% had antibody titers against BoCV Day 21: 91% had antibody titers against BoCV Seroconversion was inversely related to average daily weight gains (p < 0.06) BoCV is highly contageous and affected gain when naïve animals seroconverted.

19 BoCV respiratory infection on health and performance (Lathrop, AJVR, 2000) 837 cattle, 4 feedlots, 2 states (Ohio and Texas) IN Shed BoCV Serology Outcome Yes No Yes Seronegative on arrival Seronegative on arrival 1.6X more likely to be treated than non-shedding, seropositive cattle Slightly higher risk to be treated 2.2X more likely to have pulmonary lesions at harvest In this study, neither BoCV shedding or seroconversion were predictors of average daily gain (ADG) In another study, seropositive cattle gained 13 lbs. more than seronegative cattle. (Hasoksuz, JVDI, 2002)

20 Vaccine study West pens 1 4: 80 calves = ½ dose of SQ killed BoCV at 5 weeks East pens 7-10: 80 calves = Intranasal MLV BoCV at 5 weeks Middle pens 5&6: 40 Non-vaccinated controls

21 Vaccine study results <5% morbidity No mortalities Weighed at 5 months SQ Killed BoCV = 399 lbs. IN Mod LV BoCV= 385 lbs Neg controls = 373 lbs Significance? Killed SQ vs. Controls p =0.01 ML Intranasal & Controls p=0.20

22 Updated vaccine study <5% morbidity No mortalities Weighed at 5 months IM MLV BoCV = 425 lbs. SQ Killed BoCV = 399 lbs. IN MlV BoCV= 385 lbs. Neg controls = 373 lb.

23 BoCV Nasal Swab Monitoring Date Test result April 2011 (no vaccine) Positive, Ct 30 August 2011 (vaccinated with killed IM) Positive, Ct 25 March 2013 (vaccinated with killed IM) Positive, Ct 30 March 2013 (vaccinated with killed IM) Positive, Ct 34 in 1/4 calves June 2013 (switched to IM Calf Guard) October 2013 (continued IM Calf Guard) June 2014 (continued IM Calf Guard) March 2015 (continued IM Calf Guard) negative negative negative negative

24 Vaccination expectations Positive impact Dairy calves BEFORE grouping (hutch to pen) Beef calves BEFORE bunching on pasture and/or weaning Mid to late lactation dairy cows BEFORE winter Show cattle BEFORE shows* *Cold water wash racks appear to facilitate transmission at shows (personal observation) Unlikely vaccine impact Young dairy calves on autofeeders. Exposure is immediate & overwhelming. Upon feedlot arrival. Exposure is immediate and high. In the face of disease. Exposure is overwhelming. Some research has shown BoCV is not affected by interferon.

25 BoCV: Pathology of infection and diagnosis

26 Bovine coronavirus Fragile, host-derived lipid envelope. 1. Susceptible to heat, UV light and disinfectants 2. Envelope needs to remain intact for entry into cells. 3. Surface antigens or keys can be covered and neutralized by BoCV antibodies. 4. Diagnosis - Virus needs to be fresh and remain intact for detection by electron microscopy. Dead, degraded virus is easily detected by PCR. 5. Virus isolation (growth) is challenging.

27 Percent Diagnosis - Comparing EM and PCR on 300 fecal sample from calves 80% 70% 60% 50% 40% 43% 70% In these fecal samples, PCR was 5X more sensitive than EM. 43% 30% 20% 10% 0% 8% EM PCR Rotavirus Coronavirus EM PCR

28 Calf diarrhea, the most lethal syndrome of BoCV: Acute mucohemorrhagic enterocolitis leading to bicarbonate loss, metabolic acidosis and cardiotoxic hyperkalemia. Calf colon IHC: Necrotic colitis

29 Upper respiratory BoCV: Histopathology & IHC Trachea H&E and IHC H & E histopathology: Attenuated epithelium. Nasal turbinate H&E and IHC

30 Is BoCV a respiratory pathogen? If so, what is the lesion? IBRV Erosions, ulcers and necrosis with intranuclear inclusion bodies. BRSV Syncytial cells lining airways with intracytoplasmic inclusion bodies. PRRSV Interstitial pneumonia and necrotizing alveolitis. SIV Necrotizing bronchiolitis. Bovine coronavirus????.

31 Case 1 Beef calf developed summer pneumonia in late July and died. Trachea BoCV was found on a nasal swab, in the sinus cavity, facial nerve, retropharyngeal & submandibular lymph nodes, salivary gland and olfactory (smell) nerve BoCV in trachea (IHC)

32 Case 2 Sinus & ear involvement Two dairy calves die of respiratory disease. The frontal sinus cavity contained pus (sinus infection). BoCV was found in the sinus cavity, lymph nodes, salivary gland and inner ears.

33 Case 3 Sinus & vagus nerve Feedlot calf dies of bloat and a ruptured diaphragm. Necropsy also reveals some BRDC. Frontal sinuses were congested and contained pink fluid loaded with BoCV. BoCV was also detected in the VAGUS nerve Tissues were also positive for BVDV. involvement

34 Case 4 Eye involvement 10-day-old dairy calf dies of bovine coronavirus enterocolitis. Although the eyes appeared normal, there were loss of goblet cells, mild erosions and lymphocytic infiltrates in the 3 rd eyelid. BoCV was detected in the 3 rd eyelid by IHC. Diseased Normal 3 rd eyelid: Epithelial erosion, loss of goblet cells and lymphocytic infiltrates BoCV IHC of 3 rd eyelid (above)

35 Pink eye decision tree Question: Is it affecting a large number cattle in both eyes? Or a few animals in one eye Many animals, quickly, in both eyes Has there be a significant increase in flies and cattle bunching? YES NO Focus on contagious pathogen (IBRV, Coronavirus?) Focus on getting cattle away from each other (usually a fly, or heat problem). Spray flies. Few animals, one eye only? Focus on sources of trauma. Insects, tall grasses, head throwing from biting flies, kicking cows, tree and brush branches. Possibly dust and blowing bedding.

36 Case 5: Tonsil Feedlot animal dies of Mannheimia hemolytica BRDC. A majority of the tonsil is lined with attenuated epithelial cells. The lumen contain sloughed epithelial cells and hemorrhages Cilia Goblet Portions of the tonsil are normal with mature ciliated epithelial and goblet cells No cilia, no goblet cells

37 Case 5: Tonsil continued Attached and sloughed epithelial cells stain positive for BoCV BoCV IHC BoCV IHC

38 Case 5: Dissolved mucus layer 400X, Mucicarmine stain, Sinus Healthy respiratory airways have a stable, consistent mucus layer (homogenous pink material) The mucus layer is missing in this BoCV infected tonsil. One goblet cell remains 400X, Mucicarmine stain, Tonsil Goblet cell

39 Mucus and blood sloughs in the feces of cattle with enteric BoCV. Normal Cilia Mature Goblet cells producing mucus Airway BoCV enterocolitis. Blood-stained mucoid feces. Necrotic crypts stain positive for BoCV by IHC

40 BoCV in tissues from 18 cases of BRDC Nasal swabs and/or enteritis yield the most Nasal Inner ear Retrophar Mandib Salivary Sinus positive results Swab Lung Intestine swab Lymph N Lymph N Gland swab (pool) (pool) neg neg neg 20 (pool) neg neg (pool) neg 20 (pool) 35 neg 39 neg (pool) neg (pool) neg 38 neg neg 9 30 neg 35 neg 38 neg neg neg neg 11 neg neg neg neg neg 39 neg neg neg neg neg neg neg neg neg (pool) neg 38.7 neg neg neg (pool) neg neg neg neg neg 17 neg neg neg neg neg neg neg neg neg Number 15/18 6/13 9/11 4/11 12/18 10/15 8/18 8/18 % positive 83% 46% 81% 36% 67% 67% 44% 44% Average Ct

41 BoCV in nerves Facial Olfactory Brain Trigeminal Optic Conjunct Vagus nerve nerve Ependyma Nerve nerve nerve neg 2 neg neg neg neg neg neg 5 40 neg neg 39 (susp) 6 neg neg neg neg 7 38 neg neg 8 neg neg neg 9 neg neg neg neg 10 neg neg neg neg 11 neg neg neg neg neg 12 neg neg neg neg neg neg neg neg neg neg (susp) neg neg neg 16 neg neg neg neg 39 (susp) 17 neg neg neg neg neg neg neg neg neg Number 6/18 1/18 0 1/11 1/12 3/4 1/4 % positive 33% 6% 0 9% 8% 75% 25% Average Ct

42 BoCV Diagnosis Bovine Respiratory Coronavirus Virus Features Shed Early: Peak sheding in a feedlot = 4 days post arrival Shed in high amounts Highly contageous Virus is stable when frozen Sample consideration Sample at first sign of disease Nasal swabs yield very high numbers of virus If 20% of cattle are infected and you want to be 90% sure = sample 10 cattle Freeze swabs immediately. Can be frozen for months Comment Avoid cattle that have been treated multiple times Pooling up to 5 samples is appropriate. The lab will do the pooling. Virus levels after two weeks are expected to be lower. PCR finds virus, dead or alive. If attempting to grow virus, seek special media. Diagnostic Summary = If you nasal swab 10 cattle, early in the disease episode, and pool in 2 groups of 5, you can be about 90% sure of the diagnosis. Cost = $60 ($30 per pool of 5). The task of collecting and freezing nasal swabs can, and should, be done by the producer.

43 Swabs Becton Dickenson Culturette swabs with liquid Stuarts media is a good, all-purpose swab. Cotton swabs shipped in a red-topped tube with 1 ml of saline is also acceptable. Avoid swabs with gel media as it can negatively impact a PCR reaction. Avoid swabs with charcoal media. If attempting to isolate (grow) a virus, then the VDL can send virus isolation media.

44 Take-home messages 1. BoCV antibody titers, from either vaccination or natural exposure, don t appear to last longer than 6 months. 2. BoCV infection appears to compromise the innate mucociliary apparatus of the upper respiratory tract. 3. IM (and likely SQ) vaccination with MLV prior to exposure appears to alleviate upper respiratory disease when given prior to exposure.