Disease Causing Viruses

Viruses cause a number of economically important diseases in birds and animals. Some disease causing 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 harbored in various animals. Influenza viruses, which persist in their natural bird host, can also sometimes infect humans. The study of animal viruses contributes to the understanding of viral infection in general. Foot-and-mouth disease virus (FMDV) is a picornavirus and is the primary cause of an acute systemic vesicular disease that affects cattle worldwide. It is a highly variable and infectious virus. The viral genome of Foot-and-mouth disease virus consists of a single stranded positive RNA. Pestiviruses cause diseases in animals such as Classical swine fever (CSF) and Bovine viral diarrhea or mucosal disease which is known as BVD/MD. These are modifiable and curable diseases and eradication programs are in place in various countries around the world. Animal pestiviruses have a lot of similarities with the human hepaciviruses. Pestiviruses can establish persistent infection which often goes unobserved.

Arteriviruses are classified in the order Nidovirales. Arteriviruses are enveloped, small viruses with an icosahedral core containing a positive-sense RNA genome. Equine arteritis virus or EAV, porcine reproductive and respiratory syndrome virus or PRRSV, lactate dehydrogenaseelevating virus or LDV of mice and simian hemorrhagic fever virus or SHFV all belong to this family of viruses. The arteriviruses are very species specific although they share a variety of biological properties such as morphology, genome organization, structural proteins, replication strategy, and the ability to establish prolonged or persistent infection.

Coronaviruses viruses are positive-strand, enveloped RNA viruses. Viruses of this group are important pathogens of birds and mammals. They cause respiratory tract or enteric infections in a variety of animals including humans, livestock and pets. Severe acute respiratory syndrome or SARS is caused by a coronavirus called SARS-CoV. CoV based vectors have potential in vaccine development and for the gene therapy. Another type is the Hendra and Nipah Virus. The paramyxoviruses Hendra virus or HeV and Nipah virus or NiV have emerged in humans and livestock in Southeast Asia and Australia. Both viruses are contagious, highly virulent, and capable of infecting a number of mammalian species and causing potentially incurable even fatal diseases. Avian Influenza is a large variety of influenza viruses infect wild aquatic birds. Rarely 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 or BTV causes serious disease in livestock goat, sheep, and 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 structural and molecular levels.

African swine fever virus or 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, bushpigs warthogs, and soft ticks with no disease signs.

• John Palsson
• 23/11/2008, 2:59 PM
• 0 Comments