In the women's clinic for all pregnant women is assigned a blood analysis on a number of infections. If the conclusion of the said "CMV IgG antibodies were found" - what it means and what threatens mom, fetus and infant?
With the advent of fast (screening) diagnostic techniques, medics appeared a powerful tool for research on the subject of carriage of many viral infections.
With this spectacular data were obtained: about 90% the world's adult population were infected with cytomegalovirus. Such an indicator is formed by identifying specific immunoglobulins (antibody) in the blood of examined people.
Fact! By it's nature, cytomegalovirus (CMV) It belongs to the family of herpes viruses. More specifically - is a human herpes virus 5 type.
Like all members of this family, CMV has a number of clinical features:
- Widespread among human populations (over the age 18 years are infected by 70 to 95% the population, depending on the region of residence).
- Prone to persistence (once infected by, completely get rid of it is almost impossible).
- While maintaining immunity, It is "under control" and does not cause harm (mostly it remains dormant).
- The weakening of immunity is activated and begins aggravation.
It is able to reproduce inside cells of many kinds - from epithelial to lymphocytes.
Important! Wanted in pregnancy, since damages placenta, It penetrates through it and can infect the fetus in utero. In the early stages it leads to the abortion, anomalies of fetal development. At later - causing congenital cytomegalovirus infection.
Given the high prevalence of the pathogen, a blood test for CMV included in the list of mandatory investigations, are assigned to pregnant women in antenatal clinics (cytomegalovirus - one of the infections TORCH-complex).
Almost everywhere, the prevalence of CMV (you can still hear the term - ubiquitous) causes, that the infection can be detected in many people. However, all in a row there is no need to carry out research.
Medics highlighted certain categories of people, for whom such an analysis shows:
- women, who are planning to become pregnant.
- pregnant, who was previously the pathology of pregnancy, miscarriages and fetal fading.
- mothers, whose children were born with developmental abnormalities, or there have been cases of stillbirth.
- infertile couples.
- children, born with a low Apgar score and / or congenital diseases.
- HIV-infected people.
Among all subjects, the largest percentage falls on pregnant women.
When CMV infection in humans is formed a so-called "non-sterile" immunity, in contrast, let us say, chickenpox. We briefly describe the mechanism.
One of the targets of the virus are immune system cells - lymphocytes. Once inside the lymphocyte, it builds its genetic information (DNA virus) into the cell nucleus, where it is no longer possible to extract. How many will live lymphocyte (and some of them live as, as the man himself), as much and will live inside the CMV.
Hence the two facts:
- cellular immunity, whose representatives are lymphocytes, is not able to cope with the cytomegalovirus.
- Can destroy only those viral body, which extend from the infected cells into the blood. And for this organism produces antibodies, which is scientifically called immunoglobulins.
This is a large group of protein molecules, which are divided into different categories, variously implement a protective function and appear in a different time from infection. Synthesized one of the subtypes of lymphocytes (B-lymphocytes).
Fact! Due to immunity, even infected women are able to become pregnant, successfully gestate and give birth to perfectly healthy babies.
Screening methodology is based on the detection of antibodies in human blood.
Allow to reveal their current serological test system based on enzyme immunoassay (IFA) or reaction immunoflyuorostsentsii (REEF). The detailed mechanism of the study is quite complicated and is not the subject of this article.
We can also look directly viral DNA by polymerase chain reaction (PCR), but it is very expensive analysis.
In respect of cytomegalovirus infection, the most important two antibodies category:
- Immunoglobulin class G (IgG).
- Immunoglobulin class M (IgM).
The antibodies of class M (IgM) appear at the very beginning of the immune response. Hence their discovery indicates, that active replication of the virus began relatively recently. This can be primary infection or exacerbation of latent infection.
Antibodies of class G (IgG) appear later. If they are identified, and the person has no clinical manifestations of CMV infection, we can speak of a sufficiently long period of carriage.
interpretation of results
In this way, There are three main variants of the results:
- Identified only immunoglobulin M.
- Identified only immunoglobulin G.
- Identified two classes (IgM+IgG).
There is another option, when it marked increase in IgG level in 4 or more times the original. This indicates a worsening of infections, but must be the primary analysis, which could be compared to the current. Only in this way you will notice a significant increase in the level of (titre) IgG.
Detection of antibodies only class M indicates, that infection has occurred relatively recently and the virus is active in the breeding stage (replication). Luckily, isolated IgM during pregnancy are found very rarely.
This is due to the fact, that "thanks" to the pathogen prevalence, infection occurs early enough. And at the time of conception, the immune system is already taking the virus under control.
Detection of only IgG antibodies to cytomegalovirus - the most common analysis of the results. Says, CMV that was a long time in the blood. Now the immune system no longer allows him to actively propagate and infect new cells.
Fact! The majority of pregnant women will be just such an analysis on the TORCH-infection. When detected cytomegalovirus IgG antibody, it means, moms immunity has translated into a latent infection for the fetus and is not in danger.
For greater confidence in the results, the study was repeated later 14-21 day. This will help to say exactly, if the antibody titer increases. I.e, whether there is a threat of acute infection.
If the blood revealed a combination of IgM and IgG antibodies to cytomegalovirus, We can assume two options:
- The analysis is done then, When the primary infection proceeds in the damping step (from the active to latent).
- There has been a worsening of infections, and the body tries to regain control of the virus.
In this case, for the management of pregnancy means a lot period, where such a combination is detected. The less time remains before delivery, the better the prognosis.
Important! The greatest risk to the fetus occurs, if combined with IgM high titre IgG, that points directly to the acute course of CMV infection.
Value have some special properties of antibodies. Let's get acquainted with them more, and then consider sochetannyj variant IgG + IgM.
The properties of antibodies
Immunology - a very difficult science, rich and unique terminology. With regard to immunity against cytomegalovirus infection interest are affinity and avidity of CMV-IgG.
deciphering the terms:
- The ability to detect antibodies and antigens to bind to proteins on the surface of their target namely (in our case - cytomegalovirus). This affinity, original antibody specialization.
- Characteristics of, how firmly immunoglobulins bind to its target - avidity.
In other words, If the antibody binds to the virus in one place - low avidity, this relationship can break up. When the contact points greater, avidity increases: tear antibody against the virus is already difficult, and a target forever loses its activity.
Modern test systems for IFA antibodies cytomegalovirus, They show a certain percentage of immunoglobulins vysokoavidnyh. I.e, allow us to estimate the index of avidity (AND A).
The higher this percentage, the more time has passed since infection.
Important! A high avidity index points, that the immune system has to deal with the infection for a long time. AND, respectively, conversely: low avidity of evidence in favor of relatively recent infection. Maximum IA CMV-IgG is about 98%.
IgG - quite large and complex proteins. That is why, first synthesized simpler antibodies with low avidity, subsequently replaced by the more advanced, vysokoavidnymi forms.
Total allocated three varieties:
- CMV low avidity IgG to.
- Antibodies with an average avidity.
- Vysokoavidnye-cytomegalovirus immunoglobulin.
Sometimes doctors are limited to two categories: low avidity, if the agency is not over 45% and vysokoavidnye - all, that more 45%.
The most valuable is agency for obstetrics. on, what forms of IgG are found in conjunction with the CMV IgM, It depends tactics further support pregnant.
they differ in molecular structure. Researchers identify four types of immunoglobulins G, depending on the molecular weight. The practical value of such information until the study.
planning for pregnancy
Women in the "position", and the fruit is very susceptible to CMV infection. It is therefore necessary to make a first analysis at the stage of planning of pregnancy.
If found IgG class with a high avidity index - nothing to worry about. Identifying low avidity antibodies should be an occasion to, to postpone the conception.
Returning to the embodiment, when blood are together with IgG IgM. Similar results were measured:
|IgM + vysokoavidnye IgG||Infection occurred a long time, process occurs aggravation. It requires further examination of the immune system, to find the cause of immunodeficiency.|
|IgM + low avidity IgG||We are dealing with primary infection. body copes, possibly, it should be a little help. doctor decides.|
When the analysis results from the combination of IgG and IgM any IA, you need to consult a qualified physician listen to his opinion, and follow all instructions. This will give the opportunity to safely get pregnant, carry and give birth to a healthy baby.