A brief introduction of adenovirus

Adenovirus known to have 52 species, were named adl ~ ad52, the most detailed study is ad2. The EI region is located on the left side of the viral genome and can be further divided into EIA and EIB, which are related to cell transformation. The EII region encodes a DNA binding protein and participates in viral replication. The EIII region is involved in viral replication. Region encodes a glycoprotein present on the surface of the host cell; the EIV region is located at the right end of the ad2 genome and is regulated by the DNA-binding protein encoded by the EII region; the fifth transcription unit synthesizes ad2 protein IV in the middle of the viral infection.

Adenoviruses are carcinogenic to rodents, or can be transformed into rodent cells cultured in vitro. Transforming cells requires only part of the adenovirus genome, which is located at the left end of the genome, which accounts for about 7% to 10% of the entire genome. Although the adenovirus is widely distributed, but the human body does not appear carcinogenic. Human cells are a class of permissive cells, which allow the virus to infect and invade cells to replicate and proliferate in the cell, resulting in the release of a large number of progeny viruses. Adenovirus particles were not detected in a variety of human tumor cells cultured in vitro, but there was adl2 integration site on human chromosome 1, which means that human cells may also be non-permissive cells for adenoviruses, Cells After virus infection, the virus can not replicate in the cell proliferation, but can be integrated in the infected cells within the genome. These cells are transformed by the virus, the phenotype is changed, and the passage can be cultured indefinitely in vitro.

The chemical composition of adenovirus

Adenovirus is a non-enveloped double-stranded DNA virus, the genome of about 25-45kb, theoretically encoding 22-40 genes. Capsid  was a regular 20-sided structure, a diameter of about 80-110nm. The capsid contains 240 hexons, 12 pentons and 12 cousins, along with other small proteins such as VI, VIII, IX, IIIa and IVa2. . The six-associated protein is the main protein that forms the 20 capsid surface of the virus capsid. The top of the 12 capsules is composed of five pentamer subunits and three cilia proteins. Twelve cilia are based on the pentapeptide protein. Protruding, ciliary hair to form the knob. The conjunctiva and ciliated head region can bind to the viral receptor on the cell surface and play a very important role in the process of viral infection.

Adenovirus virus classification

Classification and since the last century 50's found and successfully isolated adenovirus has been found in more than 100 serotypes, including human adenovirus 49 species, divided into A, B, C, D, E and F six sub-sub- Group. Gene therapy commonly used human type 2 and type 5 adenovirus in serological classification are C subgroup, in the DNA sequence of 95% homology. Both of them have very strong proliferative ability, and the titer can reach 109pfu (plaque forming unit) / ml. The copy number of genome in single cell can reach 104 (accounting for 10% of the total DNA of cell). The virus particles were stable and could reach 1010 ~ 1011pfu / ml by CsCl gradient centrifugation, which satisfied the requirement of animal experiment.

Adenovirus life cycle

Adenovirus life cycle can be divided into two distinct but can not be separated from the two stages. The first stage involves adenovirus particles adhering to and entering the host cell, releasing the genome into the host cell nucleus, and selectively transcribing and translating the early genes. At this stage, the cells are ready for viral genome replication and adenovirus late gene expression and eventual release of the mature infectious particles, the second stage. The first stage will be completed in 6 to 8 hours, the second stage is faster, only 4 to 6 hours.

Adenovirus prevention and treatment principles

Adenovirus formalin-inactivated vaccines have been used for the prevention of certain populations and may be replaced in the future by attenuated live vaccines that are cultured with diploid cells. However, adenovirus has carcinogenic effects on animals, people on the role of the whole virus vaccine and safety concerns. In addition to strengthen the swimming pool and bath water disinfection, water-borne conjunctivitis can minimize the risk of outbreaks in the eye examination should be strictly aseptic operation, the equipment used to fully sterilization, but also control epidemic conjunctivitis happened. At present the treatment of adenovirus infection is still no effective drugs.

How to prevent adenovirus

Adenovirus infection is mainly prevalent in winter and spring, easy in kindergartens, schools and military recruits in the popular outbreak. In general, adenovirus mainly through the respiratory droplets, eye secretions, respiratory or contact through the transmission; intestinal infections spread mainly through the digestive tract. Its preventive measures and other respiratory and gastrointestinal infectious diseases prevention is similar, mainly wash their hands, ground disinfection, to avoid contact with patients and their respiratory droplets. Indoor and more ventilation to keep the indoor environment clean; winter and spring popular season as little as possible to personnel-intensive public places, wear a mask when away, to avoid contact with patients to prevent infection.

In the event of acute fever, sore throat and conjunctivitis symptoms, as soon as possible to the hospital, early isolation, early treatment. A group of more than 5 people the incidence of disease in a timely manner to the epidemic prevention departments in the region report, take timely and effective prevention and control measures to prevent disease spread. Adenovirus in the epidemic season, nurseries of children with upper respiratory tract infection should be home to rest, so as to avoid the spread of the epidemic. As far as possible after the illness in the vicinity of the hospital, to avoid the patient more concentrated observation room infusion of large hospitals to prevent cross-infection. Severe cough and dyspnea symptoms are more serious cases, should be promptly admitted to the hospital for treatment, so as not to delay the disease.