Julia Ridpath presented information on HoBi-like viruses, a newly identified species within the pestivirus genus. HoBi-like viruses cause clinical signs similar to BVDV1 and BVDV2, including respiratory and reproductive disease. They can establish persistent infections and are transmitted between cattle and other livestock species. Surveillance studies in the US detected exposure to HoBi-like viruses in over 80% of cattle serum samples tested, with some regional variation. Vaccines provide incomplete cross-protection against HoBi-like viruses. Further research is needed to understand the impacts of these emerging viruses and develop effective control strategies.

1. Julia Ridpath
National Animal Disease Center
ARS/USDA
Ames, IA

2. What’s in a name?
 BVD
 Umbrella term for a wide range of clinical
presentations
○ Acute and persistent
○ Reproductive
○ Enteric
○ Respiratory
○ Immunosuppression
 First causative agent isolated called
○ Bovine Viral Diarrhea Virus (BVDV)

3. Pestivirus genus

4. HoBi-like virus
BVDV3
Atypical pestivirus
BVDV1
BVDV2
HoBi-like

5. HoBi-like virus reports

6. Strain/
reference
Temperatu
re
Respiratory
signs
Decrease in
WBC*
Viremia Shedding Seroconversion
HoBi_D32/00/
Schirrmeier et
al. 2004
Mild
increase
No clinical
signs
Slight
leukopenia
+
dpi 5
Nasal shedding
from dpi 3 to 6
+
Italy-1/10-1/
Decaro et al.
2011
40°C at dpi
3 and 7
Mucoserous
nasal discharge
from dpi 3 to 10
Reaching
about 50%
from dpi 3 to
10
+
dpi 5 to
24
Nasal and fecal
shedding from dpi
5 to 21 and 7 to
21, respectively
First detected at
dpi 14. Median
titer of 512 at dpi
21-28
Th04_Khonka
en/ Larska et
al. 2012
Around
39°C at dpi
7 to 10
Conjunctivitis,
nasal and ocular
discharge and
moderate cough
Around 40%
from dpi 5 to
7
+
dpi 5 to 9
Nasal shedding
from dpi 5 to 7 in
nasal swabs
Mean titer at dpi
14 of 54 and
1763 at dpi 42

7. Bovine pestiviruses acute
infections
 Compare clinical presentation of calves
following infection with;
 High virulence BVDV2
 Typical virulence BVDV2
 HoBi virus
 Results
 Similar to typical virulence BVDV2
○ Low grade fever of short duration
○ Reduction in circulating lymphocytes

8. Impact of HoBi-like viruses on reproduction
Reproductive/PI infections
Inoculation of 7 pregnant heifers (85
days gestation) resulted in
•1 late term abortion
•2 calves that died within 24 hrs
•Hemorrhagic gut
•4 clinically normal calves that are
persistently infected with a HoBi like
virus

9. 


BVDV1 BVDV2 HoBi-like
Immunosuppression
X X X
Reproductive disease
X X X
Respiratory disease
X X X
PI
X X X
Mucosal disease
X X X
Hemorrhagic
Syndrome X*

10. BVD
 More accurate to say causative agent is
a Bovine Pestivirus
 Bovine Pestiviruses – 3 species
 BVDV1
 BVDV2
 HoBi-like viruses (BVDV3)

11. BVDV1 BVDV2 HoBi-like
1st report 1946 1987 2004
Asia X X X
South America
X X X
Europe X X X
North America
X X
Africa X X
Australia X

12. HoBi-BVDV antigenic relationship
Bauermann et al. 2013

13. NADC/Novartis Study
 Determine protection afforded against two
different HoBi-like viruses by killed and
modified live vaccine*
 Serum from vaccinated cattle provided by
Novartis Animal Health
○ Study typical for vaccine validation
○ 25 animals per group
 Results
 Detection of virus neutralizing antibodies
○ % Vaccinated cattle with neutralizing antibodies
 MLV - 65% HoBi-like viruses
 KV - 34% HoBi-like viruses

14. Species/
subgenotype
Virus
Lowest
titer
detected
Lowest titer
detected/
genotype
BVDV -1a
VM 4.5
4.37443 4.3
C24V 4.1
BVDV-1b
NY-1 4.5
4.4NE 4.3
TGAN 4.5
BVDV-2a
890 4.5
4.41373 4.1
296nc 4.7
HoBi-like
HoBi
D32/00
4.5 4.5
Diagnostic
Antigen capture ELISA Panpestivirus primers
Serology
* *
**
Commercial ELISA
Test 1 – missed 22%
Test 2 – missed 78%

15.  Calves, sheep, goats, pigs;
2 groups (3 to 5 animals);
 Group 1 (GIn) inoculated with HoBi D32/00 and Italy-
1/10-1;
 Group 2 (GEx) exposed to PIs (one PI from each virus
strain) for 30min, 2x/day for 7 days.
 Based on virus isolation and/or seroconversion
both inoculation and PI exposure resulted in
transmission to all 4 species
Transmission study

16. • No reports of detection virus in cattle herds;
• Two contaminated FBS lots originated in US (Xia et al., 2011);
• Test of FBS lots:
72 US negative samples;
9 contaminated samples from US;
Pestivirus search:
RT-PCR;
ELISA;
Virus isolation.
Specific antibody search:
ELISA;
Virus neutralization test.
North America status - what we know…

17. Surveillance for bovine
pestiviruses
 PI
 Low incidence and lack of specific tests
 May have sample stability problem with
HoBi-like viruses
 Exposure – Serology
 No problem with storage of samples
 It is possible to differentiate serological
response

18. Detecting HoBi-like PI’s
Bauermann et al. 2014

19. PIs
Ear notch - IHC
HoBi-like
BVDV1 BVDV2
Bauermann et al. 2014

20. Heifer/virus
HoBi
D32/00
BVDV1 BVDV2
933
HoBi-like
53232 3327 2896
391 40342 416 955
622 53232 416 4390
478
BVDV1
1911 6654 1448
541 630 4390 478
578 274 630 137
902
BVDV2
1097 208 6654
911 1911 955 7643
935 1663 1448 7643
Neutralizing antibodies – heifers serum
HoBi-like PI generation
Bauermann et al., unpublished

21. Surveillance using samples from brucellosis testing
program
Virus neutralization
- BVDV-1
- BVDV-2
- HoBi-like
Location of packing
plants
200 serum samples per month for a total of 2000 samples

22. 1972 total samples

23. Results – Average titers
 Just averaging titers
is not very
informative
 Variation among
cross reactivities
developed by different
animals
 Variation among sera
○ High titer sera versus
low titer sera
 Comparative ratios
0
1
2
3
4
5
6
7
8
9
BVDV1 Log2
BVDV2 Log2
HoBi-like Log2

24. Comparative titer ratios
(3 X A)/(A+B+C)
Where A, B and C are titers against the three
different bovine pestivirus species
Antibodies are specific for one species when ratio
is 0.2 higher
6 categories –
No antibodies, Clearly BVDV1, Clearly BVDV2,
Clearly HoBi-like, Clearly BVDV, Equivocal

25. 0
200
400
600
800
1000
1200
1400
No
antibodies Clearly BVDV
Clearly HoBi
Eqivocal
Number of sera placed in
categories determined by
comparison of R values

26. Samples rated equivocal
with higher titer against
HoBi BVDV1 titer BVDV2 titer
HoBi-like
titer region
6.2 7.2 7.8 midwest
8.5 7.8 9.8 midwest
9.8 8.5 10.5 midwest
7.8 8.5 9.5
Mountain
west
8.5 8.2 9.5
Mountain
west
8.2 9.8 10.5 Pacific West
avg 8.2 8.3 9.6

27. Regional differences
Exposure ranged from 81% to 96%
No antibodies
0
2
4
6
8
10
12
14
16
18
Midwest
Mountain
West Northeast
Pacific
West South
Southeast
US
No antibodies
No antibodies

29. Level of protection
0
10
20
30
40
50
60
70
< 16 16 - 256 > 256
BVDV1
BVDV2
HoBi-like
Little or no
protection
Reduce
disease but
still shed
Reduce
fetal
infections

30. Fetal
challenge
study

31. All fetuses
were PCR
positive for
HoBi-like
virus

32. Issues that need to be
addressed
 What vaccine is best?
 Globalization of vaccine companies
○ Different bovine pestivirus species present in
different geographic regions
 Protection versus surveillance
 Trade in fetal bovine serum
 Little if any regulation
 Labeling of origin does not necessarily reflect
where sera was collected
 Cross contamination in processing
 Introduction of HoBi-like viruses into Europe
theorized to be via import of contaminated FBS

33. What doesn’t kill you doesn’t necessarily
make you stronger

34. 30 days post infection with high virulence BVDV

35. Impact of infections on
developing immune system
 There is a relationship between age of
ruminants and susceptibility to infection
 Indicates that there is a choreographed
maturation process that occurs in the
immune system
 Thymus largest in neonate and involutes
with age
 Thymus induces maturation of other immune
tissues
 Stress and disease results in early involution

36. Aftermath of neonatal
infections
0
50
100
150
200
250
Thymus-cervicalweight(g)
Non
infected
Typical
virulence
Enhanced
virulence
Destruction of thymus
evident 14 post infection

37. Control
HoBi D32/00
Italy-1/10-1
►Thymus
0
1
2
3
4
5
6
20-30 30-40 40-50 50-60 60-70
Percentage of reduction
Thymus reduction in calves
Number of calves
Bauermann et al., unpublished

38. ►Thymus Non infected
2 weeks after acute bovine pestivirus infection

39. Emerging pestiviruses besides
HoBi-like viruses
 Porcine
 Bungowannah
○ Limited sporadic outbreaks
 Atypical Porcine Pestivirus (Congenital tremors)
○ Newly identified using NGS
○ Preliminary results indicate widespread in US
 Wildlife
 Giraffe
○ Several isolations, prevalence unknown
 Pronghorn
○ Circulating in mule deer, antelope, mountain goat
and big horn sheep in US

40. Zoetes
Animal
Health