HERPESVIRIDAE

J R GILKERSON - Professor of Veterinary Microbiology, BVSc, BSc (Vet), PhD, Department of Veterinary Biosciences, The University of Melbourne, Building 400, Corner of Flemington Road and Park Drive, Parkville, Victoria, 3010, Australia
C R WILKS - Professorial Fellow, BVSc, MVSc, PhD, FANZCVSc, Melbourne Veterinary School, The University of Melbourne, Building 400, Corner of Flemington Road and Park Drive, Parkville, Victoria, 3010, Australia
C A HARTLEY - Senior Lecturer in Veterinary Virology, BSc (Hons), PhD, Faculty of Veterinary and Agricultural Science, The University of Melbourne, Building 400, Corner of Flemington Road and Park Drive, Parkville, Victoria, 3010, Australia

A General Introduction has been added to each disease chapter in an attempt to give a brief updated overview of the taxonomic, biological and other characteristics of the virus family or group of bacteria /protozoa that cause disease in livestock and, where relevant, involve wildlife. As the text of the three-volume book Infectious Diseases of Livestock is currently under revision the Editors are aware that there are inconsistencies between the updated introductions to chapters and the content of the chapters themselves. Once the chapters have been updated – a process that is currently underway – these inconsistencies will be removed.

The Order Herpesvirales contains three families of viruses, including the Family Herpesviridae which is made up of those herpesviruses that infect mammals, birds and reptiles². The families Alloherpesviridae comprise the herpesviruses of fish and amphibians, while the herpesviruses of a bivalve mollusc and abalone are categorized in the Malacoherpesviridae. Many of the viruses of the Herpesviridae family produce no known disease, but some are the cause of important afflictions of both humans and animals. Cattle, sheep goats, horses, donkeys and pigs are susceptible to a variety of infections caused by one or more different herpesviruses in each species (Table 1). These infections, some of which result in economically important diseases of livestock, are described in the following chapters.

The nomenclature of herpesviruses, and particularly of those that infect ruminants, is complicated and somewhat confusing. For example, bovine (or bovid) herpesvirus 3 (BHV-3) has been used to refer not only to the wildebeest associated virus which causes malignant catarrhal fever (now known as alcelaphine herpesvirus 1), but also to bovine herpesvirus 4 (BHV-4), which in turn has variously been labelled Movar-type bovine herpesvirus, bovine orphan herpesvirus and bovine herpesvirus 5.^{1, 5, 6} The designation BHV-3 is now considered redundant and therefore bovine herpesviruses are currently numbered 1, 2, 4, and 5.²

Table 1 Members of the Herpesviridae that infect domestic livestock

α: Alphaherpesvirinae   β: Betaherpesvirinae   γ: Gammaherpesvirinae

* Provisional designation  ** Experimental cases only

This complex nomenclature is due to the changing nature of virus classification systems.  Virus classification now relies primarily on using viral genome sequences to define phylogenetic relationships and classifications.  While this has been more or less consistent with the previous system of defining relationships using host and biological properties, there have also been many naming recommendations made by successive study groups of the International Committee on the Taxonomy of Viruses (ICTV) as well as to proposals offered by unofficial groups and individuals.^{1, 2, 4–6}
Based on biological properties (such as host range, duration of reproductive cycle, cytopathology and characteristics of latent infection), the herpesviruses that infect mammals, birds and reptiles have been well studied have been placed in three subfamilies Alphaherpesvirinae, Betaherpesvirinae and Gammaherpesvirinae. ^{2, 3, 5, 6}

With an increasing number of viruses now detected only by PCR or by various sequencing methodologies, determination of biological properties of the virus is not always possible, and relatedness is determined only by sequence based phylogenetic relationships.  Genomic sequence information in full or in part together with serological relationships, have been used to propose classification into genera. ^{2, 5, 6} However, herpesviruses are at present generally referred to only by their specific names, e.g. bovine herpesvirus 2 (BHV-2).
The ICTV study group², has proposed that herpesviruses should be named after the taxonomic unit — family or subfamily — to which their primary natural host belongs. When family names are used, the word should end in -id (e.g. equid or suid) but when subfamily names are used (as in the case of primates and Bovidae), the name should end in -ine (e.g. bovine or caprine). The exceptions to this rule are viruses which infect humans, where ‘human’ is used, e.g. human herpesvirus 1.

In the following chapters, an endeavour has been made to abide by the recommendations of the latest ICTV study group of Davison et al. ² (Table 1.1).

References

1. BARTHA, A., FADOL, A.M., WEAERMAN, H. ET AL., 1987. Problems concerning the taxonomy of ‘Movar-type’ bovine herpesviruses. Intervirology, 28, 1–7.
2. DAVISON, A.J., EBERLE, R., EHLERS, B., HAYWARD, G.S., McGEOCH, D.J., MINSON, A.C., PELLETT, P.E., ROIZMAN, B., STUDDERT, M.J. & THIRY, E., 2009. The Order Herpesvirales. Arch Virol, 154, 171-177.
3. HONESS, R.W., 1984. Herpes simplex and ‘the herpes complex’. Diverse observations and a unifying hypothesis. Journal of General Virology, 65, 2077–2107
4. ROIZMAN, B., BARTHA, A., BIGGS, M.P., CARMICHAEL, L.E., GRANOFF, A., HAMPAL, B., KAPLAN, A.S., MELENDEZ, L.V., MUNK, K., NAHMIAS, A.J., PLUMMER, G., RAJCANI, J., FERNI, M., DE-THE, G., WATSON, P.H. & WILDY, P., 1973. Provisional labels for herpesviruses. Journal of General Virology, 20, 417–419
5. ROIZMAN, B., CARMICHAEL, L.E., DEINHART, F., DE THE, G., NAHMIAS, A.J., PLOWRIGHT, W., RAPP, F., SHELDRICK, P., TAKAHASHI, M. & WOLF, K., 1981. Herpesviridae. Definition, provisional nomenclature and taxonomy. Intervirology, 16, 201–217.
6. ROIZMAN, B., DESROSIERS, R.C., FLECKENSTEIN, B., LOPEZ, C., MINSON, A.C. & STUDDERT, M.G., 1992. The family Herpesviridae: An update. Archives of Virology, 123, 425–449.