Adenoviridae family is made up of two viral genera which are Mastadenoviridae (which contain viruses that infect humans and other mammals)and Aviadenovirus (which contain viruses that infect birds). Adenoviruses are one of the major viruses in this family; and they have a worldwide distribution. Adenoviruses have an icosahedral shape, and they have no envelope. They measure between 80-110 nm. Adenoviruses are resistant to ether but sensitive to formalin and lipid solvents.
They generally replicate in the nucleus and are released via the lysis of infected host cell. There are several serotypes of adenoviruses that cause infection in humans and other mammals; and adenoviruses cause several febrile illnesses in man and animals. Adenoviruses cause respiratory diseases, infantile gastroenteritis and conjunctivitis. And they also cause disease in the urinary tract. Most adenovirus infection is asymptomatic in infected individuals. The major routes of entry of adenovirus into the body of host include the mouth, the nasopharynx, and the ocular conjunctiva.
The virus replicates in the epithelial cells of the eye conjunctiva, respiratory tract and the gastrointestinal tract; and as aforementioned most clinical cases of adenovirus infection are covert in nature (i.e. they do not produce clinical symptoms). The incubation period of adenovirus infection is between 2-5 days; and patients become infectious when they are symptomatic. Adenovirus infections occur worldwide in humans as well as in a variety of animals. People at risk of infection with adenoviruses include young children, infants, the immunocompromised host and people in overcrowded military camps.
The major routes of transmission of adenoviruses in human population include the feacal-oral route and the respiratory route. Human infection with adenoviruses induces a lifelong immunity in infected hosts; and the likelihood of a re-infection with the virus is unlikely in individuals who have been previously exposed or infected. However, there is no specific treatment for adenovirus infection since most adenovirus infections in humans are asymptomatic in nature. And preventive measures depend on the maintaining proper personal hygiene especially hand washing.
The adenoviruses are of immense medical importance because they could serve as vectors for vaccination purposes and they have also been employed in gene therapy techniques. The use of adenovirus for these purposes is because adenoviruses hardly integrate their genome into the chromosome of their host cells; and the virus is one of the most studied viruses. They can be easily grown in cell culture in vitro; and adenoviruses have a higher stability than other DNA-containing viruses.
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