Question

write a six viruses of animal and there diseases

Answer 1

Alphaviruses
Alphaviruses comprise a group of small, enveloped single-stranded positive-sense RNA viruses. They are usually transmitted by arthropod vectors (usually mosquitoes). Of the thirty known species, eight are important human pathogens (e.g. Venezuelan equine encephalitis virus) whilst one, salmonid alphavirus, is of economic importance to the farmed fish industry. Due to their small size alphaviruses have historically been utilised as model systems for the analysis of viral pathogenesis. Understanding alphavirus molecular biology, pathogenesis and host interactions are key areas of research that have applications not only in disease prevention but also in permitting the exploitation of certain alphaviruses, e.g. Semliki Forest virus, as efficient gene therapy and/or vaccine delivery vehicles.

Foot-and-Mouth Disease Virus
Foot-and-mouth disease virus (FMDV) is the prototypic member of the Aphthovirus genus in the Picornaviridae family. This picornavirus is the etiological agent of an acute systemic vesicular disease that affects cattle worldwide. FMDV is a highly variable and transmissible virus. Soon after infection, the single stranded positive RNA that constitutes the viral genome is efficiently translated using a cap-independent mechanism driven by the internal ribosome entry site element (IRES). This process occurs concomitantly with the inhibition of cellular protein synthesis, caused by the expression of viral proteases. Processing of the viral polyprotein is achieved cotranslationally by viral encoded proteases, giving rise to the different mature viral proteins. Viral RNA as well as viral proteins interact with different components of the host cell, acting as key determinants of viral pathogenesis. In depth knowledge of the molecular basis of the viral cycle is needed to control viral pathogenesis and disease spreading.

Pestiviruses
Pestiviruses account for important diseases in animals such as Classical swine fever (CSF) and Bovine viral diarrhea / Mucosal disease (BVD/MD). According to the current O.I.E. list CSF and BVD/MD are notifiable diseases and eradication programms are administered in many countries worldwide. The molecular biology of pestiviruses shares many similarities and peculiarities with the human hepaciviruses. Genome organisation and translation strategy are highly similar for the members of both genera. One hallmark of pestiviruses is their unique strategy to establish persistent infection during pregnancy. Persistent infection with pestiviruses often goes unnoticed; for BVDV frequently nonhomologous RNA recombination events lead to the appearance of genetically distinct viruses that are lethal to the host.

Arteriviruses
In 1996, the family Arteriviridae was included within the order Nidovirales. Arteriviruses are small, enveloped, animal viruses with an icosahedral core containing a positive-sense RNA genome. The family includes equine arteritis virus (EAV), porcine reproductive and respiratory syndrome virus (PRRSV), lactate dehydrogenaseelevating virus (LDV) of mice and simian hemorrhagic fever virus (SHFV). Three of these viruses were first discovered and characterized a in 1964 (EAV-1953, LDV-1960 and SHFV), whereas PRRSV was first isolated in Europe and in North America in the early 1990s. The arteriviruses are highly species specific, but share many biological and molecular properties, including virion morphology, a unique set of structural proteins, genome organization and replication strategy, and the ability to establish prolonged or true persistent infection in their natural hosts. However, the epidemiology and pathogenesis of the infection caused by each virus is distinct, as are the diseases they cause.

Coronaviruses
Coronavirus (CoV) genome replication takes place in the cytoplasm in a membrane-protected microenvironment, and starts with the translation of the genome to produce the viral replicase. CoV transcription involves a discontinuous RNA synthesis (template switch) during the extension of a negative copy of the subgenomic mRNAs. The requirement for basepairing during transcription has been formally demonstrated in arteriviruses and CoVs. CoV N protein is required for coronavirus RNA synthesis, and has RNA chaperone activity that may be involved in template switch. Both viral and cellular proteins are required for replication and transcription. CoVs initiate translation by cap-dependent and capindependent mechanisms. Cell macromolecular synthesis may be controlled after CoV infection by