Julia Ridpath

National Animal Disease Center

ARS/USDA

Ames, IA

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)

Pestivirus genus

HoBi-like virus

BVDV3

Atypical pestivirus

BVDV1

BVDV2

HoBi-like

HoBi-like virus reports

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

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

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

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*

BVD

More accurate to say causative agent is

a Bovine Pestivirus

Bovine Pestiviruses – 3 species

BVDV1

BVDV2

HoBi-like viruses (BVDV3)

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

HoBi-BVDV antigenic relationship

Bauermann et al. 2013

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

Species/

subgenotype Virus

Lowest

titer

detected

Lowest titer

detected/

genotype

BVDV -1a

VM 4.5

4.3 7443 4.3

C24V 4.1

BVDV-1b

NY-1 4.5

4.4 NE 4.3

TGAN 4.5

BVDV-2a

890 4.5

4.4 1373 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%

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

• 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…

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

Detecting HoBi-like PI’s

Bauermann et al. 2014

PIs Ear notch - IHC

HoBi-like

BVDV1 BVDV2

Bauermann et al. 2014

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

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

1972 total samples

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

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

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

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

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

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

Fetal

challenge

study

All fetuses

were PCR

positive for

HoBi-like

virus

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

What doesn’t kill you doesn’t necessarily

make you stronger

30 days post infection with high virulence BVDV

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

Aftermath of neonatal

infections

0

50

100

150

200

250

Th

ym

us

- c

erv

ica

l w

eig

ht

(g)

Non

infected Typical

virulence

Enhanced

virulence

Destruction of thymus

evident 14 post infection

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

►Thymus Non infected

2 weeks after acute bovine pestivirus infection

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

Zoetes

Animal

Health