What is Cytomegalovirus?

Cytomegalovirus is a herpesvirus DNA virus. Also known as cell inclusion body virus, due to the swelling of infected cells, it has a large nuclear inclusion body.

CMV infection is very widespread in the population. The adult infection rate in China is more than 95%, and it is usually a recessive infection. Most infected people have no clinical symptoms, but invasion of multiple organs and systems under certain conditions can cause serious diseases. The virus can invade the lungs, liver, kidneys, salivary glands, other glands of the breast, as well as multinucleated white blood cells and lymphocytes. It can excrete the virus from saliva, milk sweat, urine, semen, and uterine secretions in a long or intermittent manner. It is usually transmitted via the oral cavity, reproductive tract, placenta, blood transfusion, or organ transplantation.

(A) Congenital infection

CMV infection in pregnant women can cause congenital infections through the placenta to invade the fetus, and a few cause premature, miscarriage, stillbirth or death after birth. Children can develop jaundice, hepatosplenomegaly, thrombocytopenic purpura, and hemolytic anemia. Surviving children are often left with permanent mental retardation, neuromuscular disorders, deafness, and chorioretinitis.

(Two) perinatal infection

Maternal urinary tract and cervical discharge of CMV, the baby can be infected during delivery through the birth canal, most of them with mild or asymptomatic subclinical bed infections, and some have minor respiratory tract disorders or liver damage.

(Three) children and adults infected

Infection through breastfeeding, kissing, sexual contact, blood transfusion, etc., is usually subclinical, and some can also cause heterophilic antibody-negative mononucleosis. Due to pregnancy, receiving immunosuppressive therapy, organ transplantation, tumors and other factors activate the virus latent in monocytes and lymphocytes, causing mononucleosis, hepatitis, interstitial pneumonia, retinitis, encephalitis and so on.

(IV) Cell transformation and possible carcinogenesis

UV-inactivated CMV can transform rodent embryonic fibroblasts. In certain tumors such as cervical cancer, colon cancer, prostate cancer, and Kaposis sarcoma, the detection rate of CMV DNA is high, and the CMV antibody titer is also higher than that of normal people. Viral particles were also found in the cell lines established by the above tumors, suggesting that CMV and its Like herpes virus, it has the potential to cause cancer.

Cytomegalovirus immunity

The body's cellular immune function plays an important role in the occurrence and development of CMV infection. Those with cellular immune deficiency can cause severe and long-term CMV infection, and further suppress the body's cellular immunity, such as the decline of killer T cell vitality, NK Reduced cell function.

After the body's primary infection with CMV, it can produce specific antibodies and killer T lymphocytes, and activate NM cells. The antibody has limited CMV replication ability, and has a certain resistance to the re-infection of the same strain, but cannot resist the activation of endogenous latent virus, and the exogenous infection of other different strains of CMV. And specific killing T lymphocytes and antibody-dependent cytotoxic cells can exert the greatest antiviral effect.

Cytomegalovirus microbiological diagnosis

Saliva, urine, cervical secretion and other specimens were centrifuged and precipitated. Exfoliated cells were examined by Giemsa staining microscopy to check giant cells and nuclear and plasma eosinophilic inclusions for preliminary diagnosis.

Isolation and culture can inoculate specimens into human embryo lung fibroblasts. Due to the long growth cycle of CMV and the slow appearance of cytopathic disease, for rapid diagnosis, the infected cells cultured for 24 hours can be fixed and DNA probes can be used for in situ hybridization to detect CMV DNA.

Detection of lgM antibody and lgG antibody by ELISA is suitable for early infection and epidemiological investigation. IgG antibodies persist throughout life, and lgM antibodies are associated with acute infections.

Whether it is a primary infection or a recurrent infection, when viremia occurs, peripheral blood mononuclear cells can be extracted with dextran solution, made into smears, added with CMV monoclonal antibodies, and immunological or fluorescent staining is used to detect intracellular antigens.

In recent years, the detection of CMV antigen and DNA directly from urine and various secretions using immunoblotting and molecular hybridization techniques is a rapid, sensitive, and accurate method.

Cytomegalovirus prevention principles

Ganciclovir DHPG can prevent the spread of CMV. If combined with high titer anti-CMV immunoglobulin, it can reduce the mortality of CMV pneumonia complications in bone marrow transplantation. If propionate-resistant CMV infection can use sodium phosphate, although it can permanently reduce the spread of CMV, the effect is better than the former difference. The development of a live CMV virus vaccine abroad can induce the production of antibodies, but the cancer-causing potential of the vaccine needs to be resolved

Cytomegalovirus preventive care

Perform conscious physical fitness exercises. Improving the body's immune function and disease resistance, especially in women of childbearing age, to reduce the serious harm of cytomegalovirus to the fetus.

For pregnant women or patients with chronic wasting diseases and low immunity, care should be taken to keep them away from the source of infection.

(3) Pay attention to environmental hygiene and diet hygiene.

Those who are cytomegalovirus positive in breast milk should not breastfeed.

Immune control is still in research and exploration. After intracellular infection caused by CMV, inactivated vaccine has no obvious preventive effect. When a CMV primary infection is found early in pregnancy and / or CMV antigens are present in amniotic fluid cells, the pregnancy should be terminated. Live attenuated vaccines allow the recipient to produce antibodies. It also produces cellular immunity to CMV and reduces the occurrence of symptomatic CMV infection. CMV high-valent immunoglobulin has a protective effect on symptomatic CMV infection in serum CMV-negative bone marrow transplant recipients, but it cannot prevent reinfection. Wash hands carefully after contact with urine or saliva of children to prevent acquired CMV infection.

To prevent CMV infection caused by fresh blood transfusion, the following methods can be used: Use frozen blood or washed blood; Store blood for more than 48 hours before transfusion; Use radiation-exposed blood; Use blood filter to remove blood from the blood. Giant cells.

Cytomegalovirus therapy

Human cytomegalovirus

Most patients with CMV infection are in a latent infection state; even if CMV replicates in vivo, they are mostly asymptomatic infections. At present, there are no effective and safe anti-CMV drugs, so the treatment of CMV infection is still limited to the symptomatic treatment of symptomatic infections; ganciclovin has toxic and side effects such as bone marrow suppression, so it can only be used with caution in symptomatic infections. . Propoxyguanosine (ganciclovirDHPG) can prevent the spread of CMV. If combined with high titer anti-CMV immunoglobulin, it can reduce the mortality of CMV pneumonia complications in bone marrow transplantation. If propionate-resistant CMV infection can use sodium phosphate, although it can permanently reduce the spread of CMV, but the effect is better than the former difference. The development of a live CMV virus vaccine abroad can induce the production of antibodies, but the cancer-causing potential of the vaccine needs to be resolved. ^[3]