HERPESVIRIDAE PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS Department of Pathology and Infectious Diseases, The Royal Veterinary College, Royal College Street, London NW1 OTU. Web siteWeb site

Objectives Students should be able to: Give 3 reasons why herpesviruses are difficult to control. Know the difference between immediate- early, early and late genes and their roles in disease and tumours. List the major diseases in each species of animals and the tissue-tropism of the causative virus

Replication The uncoated double stranded DNA becomes a closed circle in the host nucleus Three types of genes are involved in replication:

Herpesviruses are bad news for 4 reasons.

Virulence is associated with presence of a thymidine kinase (tk) gene, so this is deleted from genetically engineered vaccines eg to Aujesky’s virus. Tk acclerates new DNA synthesis by salvaging thymidine from degraded DNA into TTP. It has been widely used to select cells eg hybridoma's or those which are expressing recombinant vaccines see Russell and Edington, page 99.

Research. 3 growth areas

The members of the herpesviridae according to host and major disease patterns

The major members of the herpesviridae according to host and major disease patterns

Equid herpesvirus 1 (1) This is the most common cause of abortion in mares in the U.K. It also causes respiratory disease and, more rarely, paresis

Equid herpesvirus 1 (2) This is the most common cause of abortion in mares in the U.K. It also causes respiratory disease and, more rarely, paresis

Equid herpesvirus 4 This virus cannot be distinguished from EHV 1 by polyclonal sera - but can be distinguished by mAbs, PCR probes and by RE profile. It is more prevalent than EHV 1 (by a factor of 2) in the U.K., but in the majority of cases it only causes respiratory disease.

Bovid herpesvirus 1 Pathogenesis Rhinotrachietis with lacrimation then lymphocyte-associated viraemia and then latency in cranial ganglia. Can cause 75% mortality of feed lot cattle with bronchpneumonia. Viraemia can spread to cause meningo-encephalitis, especially in calves, infectious pustular vulvovaginits and abortion.

Bovid herpesvirus 2 (Bovine mammillitis virus) Moist, raised erosions/plaques on teats with spread to udder A zoonosis of milkers. Infection can be a perennial problem in winter

Bovid herpesvirus 3 (Malignant catarrhal fever virus)

Suid herpesvirus 1 *Notifiable. Also known as Aujeszky's disease, pseudorabies, "mad itch". While this has been eradicated from mainland Britain by a pig levy and area eradication scheme it is still present in much of Europe and Ireland.

Canid herpesvirus 1

Felid herpesvirus 1 The virus is widespread within the feline population. It affects the upper respiratory tract but erosions affect the bronchii and interstital pneumonia can result. Latent infections can be reactivated during boarding.. Infections are often concurrent with calicivirus and chlamydial infections.

Herpes B Virus Monkeys. Asiatic (old world) monkeys (eg macaques and rhesus) are the natural hosts. In the wild only 10% of the population carry latent virus in ganglia/have antibodies; but in captive colonies, where monkeys are kept at high density, the prevalence is frequently 60%. The lesions in monkeys are oral focal erosions, very similar to cold sores of man. New world monkeys, like man, die with encephalitis and do not excrete salivary virus.

Summary EHV1 is a disease not only of the resp tract but also causes abortion storms and paresis. Vaccines are not good and so the Jockey club has regs re isolation and transport after abortions IBR causes a spectrum of disease and live vaccines can reduce disease. Porcine herpevirus 1 is a notifiable disease which cause abortion in sows and some fatalies after encephalitis in piglets and fatal pseudorabies in carnovores and ruminants. It has been eradicated from GB, but not N.Ireland. Feline herpes can be reactivated during boarding to cause erosive lesions Herpesvirus B only causes oral lesions in monkeys, but causes a fatal encephalitis in man.