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Parainfluenza viruses
Last reviewed: 23.04.2024
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[Structure and antigenic properties of the parainfluenza virus
Human parainfluenza viruses are similar to other members of the family. Single-stranded, unfragmented minus-RNA virus encodes 7 proteins. Nucleocapsid is an internal antibody. The envelope of the virus contains glycoprotein spines (HN and F). The antigenic properties of HN-, NP-, and F-proteins distinguish 4 main serotypes of parainfluenza viruses (HPVC-1, VPHP-2, VPHCH-3, VPGCH-4). In HPV-1, VPHCH-2, VPHCH-3, there are common antigens with the virus of mumps epidemic. The hemagglutinin of viruses differs in the spectrum of action: VPHCH-1 and VPGCH-2 glue different erythrocytes (human, chicken, guinea pig, etc.), parainfluenza-3 virus does not agglutinate chicken erythrocytes, parainfluenza virus-4 adheres only erythrocytes of guinea pig.
Cultivation of viruses is carried out on primary cell cultures.
Resistance of parainfluenza virus
Human parainfluenza viruses do not differ in resistance from other members of the family.
Pathogenesis and symptoms of parainfluenza
The entrance gate of the infection is the upper respiratory tract. Parainfluenza viruses are adsorbed on the cells of the cylindrical epithelium of the mucous membrane of the upper respiratory tract, penetrate into them and multiply, destroying the cells. The edema of the mucous membrane of the larynx develops . The pathological process quickly descends and the lower parts of the respiratory tract. VIRUSEMIA is short-lived. Parainfluenza viruses cause secondary immunodeficiency, which contributes to the development of bacterial complications.
After the incubation period (3-6 days), the temperature rises, weakness, runny nose, sore throat, hoarseness and dry rough cough. The fever lasts from 1 to 14 days. VPPCH-1 and VPPCH-2 are a frequent cause of croup (acute laryngotraheronhitis in children). Parainfluenza virus - 3 causes focal pneumonia. The parainfluenza virus is less aggressive 4. In adults, the disease usually proceeds like laryngitis.
Immunity after the disease is due to the presence of serum IgG and secretory IgA, but it is fragile and short-lived. Reinfections caused by the same types of virus are possible.
Epidemiology of parainfluenza
The source of parainfluenza is a sick person, especially on the 2-3rd day of the disease. Infection occurs aerogenously. The main way of transmission of the virus is airborne. A contact and household way is also possible. Parainfluenza disease is characterized by widespread and contagious. More often than not, patients are allocated VPHCH-1 VPVCh-2 and VPHCH-3.
Microbiological diagnosis of parainfluenza
From the patient take slime or flushing from the respiratory tract and phlegm. Using RIF in the epithelial cells of the nasopharynx, antigens of the virus are detected. Parainfluenza virus is isolated on the culture of Hep-2 cells. Indication is performed by the cytopathic action of viruses, RGA and by the hemodysorption reaction, most pronounced in parainfluenza viruses - 1,2,3 (they were formerly called hemodysorbiric). Identification is carried out using RTGA, DSC, PH. Using the serological method, using RTGA, RSK or PH, it is possible to detect both antigens of the virus and antibodies in the patient's paired sera.