The animal-human interface and infectious viral diseases: genomics and molecular epidemiological approaches in “one health” context

Abstract

Viruses, considered one of the most diverse microorganisms, usually act as infectious agents with genetic material inside a coat protein. The virus always requires a living system, such as humans, animals, plants, or even bacteria, for its growth and proliferation. This character is considered an 'obligate intracellular parasite' [1]. After the initial discovery of tobacco mosaic virus (TMV) in plant by Dmitri Ivanovsky in 1892 and foot and mouth disease virus (FMDV), in cattle by Martinus Beijerinck in 1898, the number of discovery of new viruses is increasing continuously with the identification of more than 6,000 viruses [2]. Viruses are prone to recombination through which they can exchange genes between or within to increase genetic diversity and maintains evolution [3]. Host range differes from virus to virus, which classified them as a narrow host range with a species-specific host such as smallpox virus, infecting only humans [4] or broad host range such as rabies virus (RV) that can infect different mammal species [5]. The size of viruses varied from nanometers in nodamura virus to micrometers in mimivirus. The shapes vary from icosahedral in rhinovirus, filamentous in potyvirus, head-tail conformation in T7 bacteriophages etc. While morphologically, it differs from having an envelope; the capsid structure may vary, contain spikes in the outer membrane, etc. Their replication procedure and replication site vary. For example most RNA viruses prefer the host cytoplasm to replicate and assemble. In contrast, most of the DNA viruses make use of the host nucleus for the same. Viruses are classified based on different criteria, but the most conventional and widely accepted classification system is the Baltimore classification discussed below [6]