Cytomegalovirus is the hidden scourge of our time, affecting newborns much more often than the sensational virus of Zik. Although in healthy people, infection often is asymptomatic, the virus causes severe complications in people with weakened immunity. Unfortunately, modern medicine can not cure or even prevent infection.
Cytomegalovirus (CMV) is a double-stranded DNA virus, a representative of the subfamily of beta-herpesvirus. He is known to man a little more than fifty years – he was discovered in the middle of the XX century. However, even before the stillborn infants, cells similar to “owl eyes” were described, – later it became clear that they were infected with the virus. After 50 years, the same cells were found in patients who underwent organ transplantation.[wp_ad_camp_2]
Cytomegalovirus is a large virus with a size of 150-200 nm, which makes it one of the largest viruses known to modern science. His genome is a double-stranded DNA containing information for the production of more than 230 proteins.
After infection, viral proteins begin to be synthesized in the host cell with viral DNA – CMV so spreads and maintains its vital functions.
One such protein (DNA polymerase, necessary for the passage of the life cycle of the virus) plays the role of a target for the currently used antiviral drugs.
The occurrence of the virus is high everywhere. However, this indicator varies depending on age, place of residence and socioeconomic status: infection is higher in developing countries and disadvantaged groups of the population. According to the results of the surveys, on average in the USA half of the population, aged 6 to 49 years is infected with CMV. Among the 75-80-year-old Americans, the carriers are already nine out of ten. In developing countries, about one in five children are infected from one to five years old, and in elderly people, this figure can reach 90-100%.
Since the virus can cause birth defects in children, these figures force specialists to sound an alarm.
How does the virus so successfully spread? It turns out that CMV is evolving precisely so as to hide from our immune system and make itself felt only at the right moment for it, says Rich Berry, one of the authors of the research on this topic, published in the journal Cell. “However, not everything is lost,” Dr. Berry continues, “the immune system is also not inactive, it is also evolving and rebuilding as it is necessary to continue the survival of our species.” Thus, an evolutionary “arms race” arose between the virus and the human immune system, and so far the virus seems to be ahead.
Who is at risk?
Judging by the statistics, almost any group is at risk of infection. However, serious complications from the virus threaten mainly for people with reduced immune function, for example, organ transplant patients, AIDS or newborn. Preterm infants with low weight are especially susceptible to infection since their immune systems are not yet fully formed. Moreover, scientists have found that vulnerability to the virus can enhance some genetic mutations.
The virus can be transmitted through bodily discharges of infected patients: through saliva, tears, urine, feces, breast milk, semen, etc.
You can also get infected through blood transfusion or organ transplantation. In addition, on some surfaces, CMV remains viable up to six hours, and occasionally you can get infected through contact with objects.
After the initial exposure, CMV remains in the body for a lifetime. Manifestations of his presence usually depend on the state of the immune system. “CMV is not like an influenza virus that our immune system can successfully clean out of our organs,” commented Peter A. Barry, a professor at the School of Medicine at the University of California, Davis. “As soon as you get infected, it’s forever.”
In healthy people, there are often no symptoms of infection, and the virus does not make itself felt. However, the virus can be reactivated, and then the disease can manifest itself in complications of varying severity, from nonspecific febrile fever to even fatal outcome.
Moreover, some scientists believe that in fact the virus is highly underestimated and is associated with much more complications than can be found in the standard description for doctors.
Clinical diagnosis of CMV can be carried out in a short time in the laboratory, and methods of detecting the virus are numerous. Diagnostics and improved virus in pregnant women, although, according to the latest research, the standard test reveals not all cases of infection. Now there is no approved treatment for future mothers. Newborns with a moderate manifestation of the symptoms of infection are usually prescribed valganciclovir. Healthy people infected with CMV, most often do not need treatment. Treatment is usually prescribed to patients with a weakened immune system.
CMV and pregnancy
The main threat to CMV is for children in the womb. Although he is inferior in popularity to the virus of Zek, in fact, it is cytomegalovirus – the most frequent viral cause of disability and birth defects in children in the United States. Intrauterine infection manifests itself in many forms, including prematurity, intrauterine growth retardation, microcephaly, and hearing loss. The burden of disease in children with lifelong disability due to a congenital virus is estimated at $ 1.86 billion per year.
As Amy Armstrong-Heimsot from the University of Northern Arizona notes, only 13% of women have heard about this virus. About the fact that his transfer from mother to child can turn into a tragedy, the researcher learned from a colleague with undiagnosed CMV.[wp_ad_camp_2]
“Her son now has cerebral palsy and hearing and sight loss,” she says.
Particular attention is directed to women with both HIV and CMV since with such a double viral infection the risk of infection of the baby grows at times. According to studies, HIV-infected women with CMV in the urine at birth are five times more likely to transmit HIV to infants than women with HIV, but without CMV. They are also 30 times more likely to infect the newborns of CMV.
The best way to fight the virus in the future is not vaccines, but vaccines. They will help control the virus at the population level – with the help of universal immunization. First of all, such a strategy would be aimed at women of childbearing age to prevent infection of the fetus. However, of course, they are necessary for patients with transplanted organs and hematopoietic stem cells.
Although the vaccine is not yet available, the researchers seem to already have enough fundamental knowledge to create it.
There are a lot of developments with different strategies – even such giants of pharmaceutical business as Merck and GSK are engaged in them.
It’s amazing how the fight against cytomegalovirus has not yet become one of the priorities of international healthcare institutions. The development of vaccines could be accelerated by attracting public attention to this problem and appealing to political and economic organizations for help. It is to be hoped that the numerous developments of scientists to create an effective and safe vaccine are already close to success – in fact, they will save many families from the burden of the consequences of infection with the virus and save many lives.