Table 1.

Viral species from the alphaherpesvirinae subfamily included in the present review. For each virus, the acronym is shown on the left column and a brief description of the susceptible host, pathogenesis and life cycle is described on the right column.

BHV-1	Bovine herpes virus-1 infects cattle causing rhinotracheitis symptoms that predispose animals to secondary bacterial infections resulting in ‘shipping fever’. BHV-1 is also associated with conjunctivitis, reproductive tract lesions, encephalitis and fetal infections. Economic losses result mainly from shipping fever, milk drop, loss of body weight, early pregnancy termination and death. BHV-1 can establish latency within the natural host [103].
PRV	Pseudorabies virus is a pathogen of swine that causes important economic losses worldwide. It is also known by its taxonomic name, suid herpesvirus 1, or by its original name, Aujeszky’s disease virus. The disease was originally described as “mad itch” because of the intense itching symptoms. The natural host is the swine, although PRV can infect a broad range of vertebrates including cattle, sheep, dogs, cats, goats, chickens, raccoons, possums, skunks, rodents, rabbits, and guinea pigs. PRV is tropic for both respiratory and nervous system tissues of swine. Young swine are severely affected by PRV infection of the central nervous system. Older swine show symptoms of respiratory disease. Several live attenuated vaccine versions are used in PRV eradication programs [41]. PRV is commonly use by neuroscientists to study neuronal connectivity and function in animal models [21, 104].
VZV	Varicella-zoster virus (VZV) is a ubiquitous human pathogen that spreads from mucosal epithelial cells, where initial acute infection occurs, to the skin via a T cell-associated viremia, causing varicella (chicken pox) to young age patients. Viremia and cutaneous infection allow transfer of VZV to sensory nerve ganglia, where a latent infection is established in neurons. Zoster (shingles) is caused by VZV reactivation from latently infected neurons producing a painful vesicular rash (dermatome). Live attenuated VZV vaccines are effective against varicella and zoster [105].
HSV-1	Herpes simplex virus-1 (HSV-1) is a widespread human pathogen that establishes a life long reactivateable infection in neurons of the peripheral nervous system of the human host. Upon reactivation, HSV-1 particles travel in axons back to epithelial tissue causing oropharyngeal lesions. Occasionally, the infection will spread to the cornea and cause keratitis, or to the central nervous system to cause herpes simplex encephalitis (HSE) with high mortality rates [2]. Currently, no effective vaccine exists and the only treatment is based on antiviral drugs that inhibit viral replication. HSV-1 is widely used to study neuronal connectivity and function in animal models [40]. Ongoing human clinical trials are testing the efficacy of modified HSV-1 strains as oncolytic vectors [106].