Viruses cause a number of economically important diseases in animals and birds. Some viruses of animals can cause human infection or can mutate to give rise to human infection. The SARS virus, which came from an animal source, led to an outbreak of human infection and highlights the significance of viruses that are harboured in animals. Influenza viruses, which persist in their natural bird host, can sometimes infect humans. The study of animal viruses contributes to our understanding of viral infection in general. (Reference: Animal Viruses: Molecular Biology ISBN: 978-1-904455-22-6)
Foot-and-Mouth Disease Virus
Foot-and-mouth disease virus (FMDV) is a picornavirus and is the cause of an acute systemic vesicular disease that affects cattle worldwide. It is a highly variable and transmissible virus. The viral genome consists of a single stranded positive RNA.
Pestiviruses cause diseases in animals such as Classical swine fever (CSF) and Bovine viral diarrhea/Mucosal disease (BVD/MD). These are notifiable diseases and eradication programms are in place in various countries around the world. Animal pestiviruses shares many similarities with the human hepaciviruses. Pestiviruses can establish persistent infection which often goes unnoticed.
This viruses are classified in the order Nidovirales. Arteriviruses are small, enveloped, viruses with an icosahedral core containing a positive-sense RNA genome. Equine arteritis virus (EAV), porcine reproductive and respiratory syndrome virus (PRRSV), lactate dehydrogenaseelevating virus (LDV) of mice and simian hemorrhagic fever virus (SHFV) all belong to this family of viruses. The arteriviruses are very species specific although they share various biological properties such as morphology, structural proteins, genome organization, replication strategy, and the ability to establish prolonged or persistent infection.
These viruses are positive-strand, enveloped RNA viruses. Viruses in this group are important pathogens of mammals and birds. They cause enteric or respiratory tract infections in a variety of animals including humans, livestock and pets. Severe acute respiratory syndrome (SARS) is caused by a coronavirus called SARS-CoV. CoV based vectors have potential in vaccine development and for gene therapy. (Reference: Coronaviruses: Molecular and Cellular Biology ISBN: 78-1-904455-16-5)
Hendra and Nipah Virus
The paramyxoviruses Hendra virus (HeV) and Nipah virus (NiV) have emerged in humans and livestock in Australia and Southeast Asia. Both viruses are contagious, highly virulent, and capable of infecting a number of mammalian species and causing potentially fatal disease.
A large variety of influenza A viruses infect wild aquatic birds. Occasionally viruses are transmitted from these birds to other species and this may then cause devastating outbreaks in domestic poultry or give rise to human influenza pandemics.
Bluetongue virus (BTV) causes serious disease in livestock (sheep, goat, cattle). Partly due to this BTV has been in the forefront of scientific research and now represents one of the best understood viruses at the molecular and structural levels. It is a complex non-enveloped virus with seven structural proteins and a double-stranded RNA genome. (Reference: Segmented Double-stranded RNA Viruses ISBN: 978-1-904455-21-9)
Porcine Circoviruses (PCV) are the smallest viruses that can replicate autonomously in eukaryotic cells. They are non-enveloped and spherical and contain a covalently closed and single-stranded DNA genome. Two types of PCV are known. Porcine circovirus type 1 (PCV1) does not cause disease, but porcine circovirus type 2 (PCV2) causes Postweaning Multisystemic Wasting Syndrome (PMWS), a new emerging and multifactorial disease in swine.
Herpesviruses infect animals and man. There is a wide variety of different herpesviruses with different biological characteristics. In animals the most important herpesviruses belong to the Alphaherpesvirinae. Pseudorabies virus causes Aujeszky’s disease in pigs and is extensively studied as a model for basic processes during lytic herpesvirus infection. Bovine herpesvirus 1 causes bovine infectious rhinotracheitis and pustular vulvovaginitis. The avian infectious laryngotracheitis virus is phylogenetically different from these two viruses.
African Swine Fever Virus
African swine fever virus (ASFV) is a large double-stranded DNA virus which replicates in the cytoplasm of infected cells. It causes a viral haemorrhagic fever with high mortality rates in pigs, but persistently infects its natural hosts, warthogs, bushpigs and soft ticks with no disease signs.