Human cytomegalovirus
Last reviewed: 23.04.2024
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Cytomegaly with intracellular inclusions is a generalized infection of newborns caused by intrauterine infection with cytomegalovirus (CMV) or infection immediately after birth. The infection is widespread and ubiquitous, antibodies to the cytomegalovirus are found in 80% of people over 35 years old. CMV can be isolated from the cervix in almost 10% of healthy women. The disease is characterized by the appearance of large intranuclear inclusions in salivary glands, lungs, liver, pancreas, kidneys, glands of internal secretion and sometimes in the brain. Children mostly die before the age of 2. For older children and adolescents, asymptomatic infection is more characteristic. In adults receiving immunosuppressants for treatment, a severe cytomegalovirus infection often develops.
CMV is very similar to herpes simplex viruses and VZ, but differs from them according to the following signs. CMV has a longer cycle of intracellular reproduction (1-2 weeks) and therefore has less cytopathic activity, has an extremely narrow range of hosts (only humans), and is less sensitive to modified nucleosides, since it is poorly capable of inducing viral-specific thymidine kinase.
[Pathogenesis and symptoms of cytomegalovirus infection
With intrauterine infection the most severe form of the disease develops. Children can also be infected by contact or alimentary route, since patients are able to excrete the virus with urine for quite some time. CMV multiplies in the epithelial cells of various internal organs, in which it can persist for a long time. Characteristic changes in the cell in which CMV multiplies: the size of cytomegalic cells 25-40 μm, in their nuclei there are 1-2 inclusions, consisting of viral particles and nuclear chromatin, surrounded by a light rim.
With congenital cytomegaly, there is a specific syndrome characterized by signs of immature fetus, jaundice, enlarged liver and spleen, thrombocytopenic purpura, pneumonia and various injuries of the central nervous system (microcephaly, chorioretinitis, optic nerve atrophy, oligophrenia, etc.).
In children with acquired cytomegaly, hepatitis, interstitial pneumonia or hemolytic anemia develop. The virus is found in the salivary glands and kidneys, from where it can stand out for a long time. When the disease is important immunopathological reactions: immune lysis of cells with the antibody + complement system and cytotoxic lymphocytes, the appearance of immune complexes in the blood and tissues. The number of T-suppressors sharply increases, and the ratio of T-helpers to T-suppressors drops to 0.23.
Immunity is humoral in character: complement-binding and virus neutralizing antibodies appear in the serum.
Laboratory diagnosis of cytomegalovirus infection
The virus can be isolated from various pathological (including sectional) material by infecting cultures of human fibroblast cells and diploid cultures of human lung cells. After 1-2 weeks. Typical cytomegal cells appear. They can also be detected by electron microscopy of the cell sediment of urine, where the virus is present in large quantities. Antibodies in paired sera are determined in the neutralization reaction in the cell culture, as well as by DSC, RPGA, RIF, IFM, and RIM.