1. Varicella-Zoster virus (VZV):
Varicella and Zoster virus (VZV) belongs to the Alphaherpesvirinae subfamily and is the responsible for two human illnesses: varicella and zoster. Three Alphaherpesviruses are capable of infecting humans: herpes simplex virus 1 (HSV-1), herpes simplex virus 2 (HSV-2) and varicella-zoster virus (VZV). The members of this subfamily are commonly characterised by their ability to establish a latent infection in neurons. Primary infection occurs in epithelial cells leading to a skin rash and fever as a phenotype. When virions spread to adjacent sensory neurons, a lifelong infection is established (Owen, Crump, & Graham, 2015).
Both primary and secondary diseases have a significant morbidity and mortality but thanks to advances in diagnostic and the production of vaccines, it is possible to decrease their burden (Gershon, 2013).
1.1 Varicella:
Varicella (chickenpox), the primary infection of VZV, is characterized by cutaneous eruption typically seen in children. In adults, this primary infection is more severe and in immunocompromised patients, it can be followed by complications such as, high fever, pneumonia, encephalitis and hepatitis (Gershon et al., 2013). During this primary infection, the virus can be
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During this latency, no viral particle is produced but the entire genome is expressed and some proteins are transcribed. It has been identified as transcript proteins in infected human ganglia the genes; orf21, orf29, orf62, orf63 and orf66. Specifically, ORF63p (IE63) is the most transcribed protein during latency in infected human ganglia. The development of zoster is usually observed in people over sixty years old or immunodeficient patients. Instead of varicella, which occurs in the spring, zoster has no seasonal predilection (Mueller et al.,