Transcript HERPESVIRIDAE

PESTIVIRUSES
PETER H. RUSSELL, BVSc,
PhD, FRCPath, MRCVS
Department of Pathology and
Infectious Diseases, The Royal
Veterinary College,
Royal College Street,
London NW1 OTU.
E-mail
Web site
LEARNING OBJECTIVES
Students should be able to:
• identify how swine fever virus, bovine virus diarrhoea, and
border disease of sheep are related but yet distinct with
regard to antigens and pathogenicity.
• explain the pathogenesis of acute, chronic and mucosal
disease and how immune tolerant viraemic animals affect
epidemiology.
• describe the importance of bovine pestiviruses as
reproductive pathogens.
• describe in outline how swine fever virus was eradicated and
how bovine virus diarrhoea virus is controlled in the UK.
CLASSICAL SWINE FEVER
VIRUS
Epidemiology: CSFV had a worldwide
distribution but has now been eradicated from
ill Australia, NZ., USA and some European
countries eg Denmark. It can survive in
formites and pig meat eg sausage.
CLASSICAL SWINE FEVER
VIRUS
Control: Eradicated in UK in 1971 but a Chineselike virus (as defined by phylogenetics) entered UK
in 2000. It almost certainly entered via illegally
imported pigs from EU. Previous control
programme started in 1963 with crystal violet
inactivated vaccine in 1960 followed by slaughter
policy in 1963. In 1967, reported cases down to
single figures.
BORDER DISEASE VIRUS
Pathogenesis:
BORDER DISEASE VIRUS
Epidemiology:
BORDER DISEASE VIRUS
Diagnosis: Detection of antibody by ELISA
or virus by virus isolation in cell culture or by
antigen detection in ELISA are the common
methods for BVD diagnosis. This is usually
subsequent to clinical diagnosis of abortion
and the birth of 'hairy shaker' Iambs.
BOVINE VIRUS
DIARRHOEA VIRUS and
MUCOSAL DISEASE
BOVINE VIRUS
DIARRHOEA VIRUS and
MUCOSAL DISEASE
The Virus
BVDV
non-cytopathogenic cytopathogenic
BVDV Disease
Severe Haemorrhagic Disease
due to BVDV
Transmission of BVDV
Transplacental infection
Persistently infected (PI) animals
BVDV PI animals have
certain characteristics:
Persistently infected (PI) animals
BVDV PI animals have
certain characteristics:
(cont.)
Persistently infected (PI) animals
(cont.)
Mucosal Disease
Mucosal Disease
(cont.)
The cause of mucosal disease
BVDVnc infection
The cause of mucosal disease
Superinfection with BVDV c
Homologous' to persisting virus
Diagnosis
Control
SUMMARY
* Transplacental infections initiate events which have important
pathological consequences for all three viruses.
* SFV is notifiable, but has been eradicated, and the most recent
suspect cases have been due to BVD infecting pigs.
* Border Disease can cause serious losses in lambs in anyone year
due to CNS damage and poor doers with hairy coats. It is advisable to
eliminate carriers by getting rid of the entire crop of lambs that year .
* BVD is a primary enteric pathogen but also a major source of loss
through reproductive abnormalities. The nc isolates are important in
establishing persistently infected calves that are susceptible to
secondary infection with the cytopathic isolates to initiate mucosal
disease. Vaccination of cows before their first insemination is
recommended.