The root "adeno" comes from the Greek for gland, as this virus was first isolated from adenoid tissue. Adenoviruses are a family of viruses containing a linear, double-stranded DNA genome. These viruses are medium-sized (90-100 nanometers) with spherically shaped virions and non-enveloped, icosahedral capsids. There are over 51 different human serotypes of adenovirus, grouped into 6 serological groupings A-F. Transmission of adenoviruses occurs both by the respiratory and fecal-oral route. These viruses have a tropism for cells in the intestinal tract as well as cells of the conjuntival and respiratory epithelium. Infection with an adenovirus is frequently asymptomatic; however, persistent infections are possible. Seasonal variation in infection is observed. Clinical manifestations of adenoviruses include acute respiratory disease, particularly upper respiratory tract infections in children, conjunctivitis, notably epidemic keatoconjunctivitis or shipyard eye caused by adenovirus h8, and gastrointestinal illness.
The Adenovirus Family:
*Note that the adenoviruses which infect humans all belong to the Genus Mastadenovirus, subgroups A-F. Although Human adenoviruses in sub-families A and B have been noted to cause malignant tumors in rodent hosts at a relatively high rate, no oncogenesis has been associated with human adenovirus infection.
A Brief Timeline of the Adenovirus:
Discovery of Adenoviruses
Adenoviruses were identified by two groups of scientists simultaneously. Wallace Rowe and Robert Huebner at the National Institutes of Health isolated tadenovirus from adenoid tissue. The other identification ocurred through the direct collection of the virus from epidemics of acute disease.
Isolation of influenza-like virus in the Army
Maurice Hilleman, a member of the U.S. Army, was investigating the acute febrile respiratory illness that was currently an epidemic for Army recruits at the Leonard-Wood base. He initially believed the respiratory illness to be caused by an influenza virus, but could not isolate any influenza virus from specimens of affected respiratory tracts. However, he eventually identified another virus in affected human tracheal cells, which he considered to be a new agent (soon to be named an adenovirus).
Identification of 3, 4 and 7
Discovery that three types of adenovirus, 3, 4, and 7 cause most of the cases of acute respiratory diseases in Army recruits.
Adenov Vaccine Research Started
Adenovirus vaccine research and vaccine development initiated in the US.
Vaccine trials prove success
Vaccines are shown to be very effective in trials (Edmondson et al., 1966; Top et al., 1971) Specifically, oral, live-encapsulated type 4 and 7 adenovirus vaccines were administered to Army recruits at the time of their arrival at Army bases around the US, halting adenoviral outbreaks.
Adenovirus and cancer
Trentin et al. discovered that adenovirus 12 can induce hamster tumors
in the lab, which inspired a link with human cancers, although a direct
causal effect has yet to be shown.
Vaccine licensed for military
Adenovirus vaccine is licensed to be used in military populations. This resulted in almost complete control of respiratory disease epidemics in military recruits-a change from the previous situation.
Investigation: Adenovirus and Intussesception
D. M. Bhisitkul et al. investigated the connection between "Adenovirus infection and childhood intussusception", finding that nonenteric adenovirus infection and intestinal intussusception may be associated. No conclusive evidence was found regarding the connection between enteric adenoviruses types 40 and 41 and intussusception.
Vaccine production ends
The only manufacturer of the adenovirus vaccines stopped producing them in 1996.
Vaccine stock done and viral reemergence
By the middle of 1999, the stock of adenovirus vaccine was entirely depleted. Following this, adenovirus sickness reemerged as a prominent cause of sickness and reason for hospitalization among new Army trainees (Gray et al., 1999; McNeill et al., 1999; Sanchez et al., 2001).
Research indicates types 4 and 7 as prominent
Studies of adenovirus during 1999 and 2000 showed that 82% of the infections of Army recruits were again caused by types 4 and 7 adenovirus.
Adeno-caused Deaths of Army Recruits (CDC, 2001)
The deaths of two or more otherwise healthy recruits were documented to have been caused by adenovirus infection, an infection known to be vaccine-preventable (CDC, 2001).
Adenovirus type 30 outbreak in neonatal clinic
A well-documented NICU outbreak of adenovirus infection. This outbreak lasted for 6 months and involved 21 of 333 (6.3%) infants in the clinic. Initial infection control measures were successful in controlling the outbreak, but these measures were discontinued prematurely resulting in a reemergence of the outbreak and new cases. In 7 infants, the virus caused pneumonia, in 7 it caused conjunctivitis and in 1 infant, it caused both pneumonia and conjunctivitis. In another infant is caused upper respiratory tract illness and in 5 infants, the infection was asymptomatic. Overall, 6 infants died of infection. As far as treatment, 6 of the infected infants received specific therapy for adenovirus infection; intravenous immunoglobulin (IVIG) given as a one-time dose of 400 mg/kg and/or intravenous ribavirin for 3 to 7 days.
Deshka Foster - Winter 2008
Created for Dr. Robert Siegel's Humans and Viruses course
Department of Human Biology, Stanford University
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