Measles have long had to be eradicated – instead of increasing again. In the first six months of 2019, there were almost three times more cases reported worldwide than in the same period last year. The European Center for Disease Prevention and Control (ECDC) talks about the rise of measles in the European Union and in the European Economic Area (EEA). This is mainly due to five countries, including Germany, where transmissions continue to be endemic – i.e. within the population.
It has long been known that measles infection can not only be very severe and even fatal, but the measles virus weakens the patient's immune system against other pathogens. Thus, in measles infections more often than other infections such as bacterial infections of the lungs or middle ear.
A recent cohort study on smallpox in the United Kingdom (United Kingdom) found that 10 to 15 percent of children still have a significant compromise of the immune system five years after measles infection, leading to an increased incidence of secondary (further) infections.
Scientists led by prof. Veronika von Messling, Head of the Department of Veterinary Medicine at the Paul-Ehrlich-Institut (PEI), Federal Institute for Vaccines and Biomedical Medicines, is part of the German Center for Infectious Diseases Research (DZIF) and funded by the Federal Ministry of Health Education and Research (BMBF) ), in collaboration with researchers from the United Kingdom and the Netherlands, investigates the mechanisms that lead to this immunosuppression. To do this, they analyzed the diversity of immune cell receptors and the development of an important group of immune cells for immune memory, memory B cells, in unvaccinated individuals with and without previous measles infection, as well as in those vaccinated against measles. Although the genetic structure and diversity of B memory cells were stable in individuals without measles infection and in vaccinated individuals, there was a significant increase in the frequency of mutation in these individuals, as well as an altered isotype (variational) profile in individuals after measles infection. In about ten percent of people infected with measles in the study, the diversity of immune cells was even severely impaired. In addition, there has been a shift towards immature immature B cells, suggesting impaired B cell maturation in the bone marrow.
The results confirm that after measles infection, the immune system almost forgets which pathogens it has previously come in contact with. "Immunoamnesia" occurs. PEI researchers confirmed these findings on an animal model (ferret). Animals were first immunized against the flu (flu), and some animals were also infected with the mutant dog measles virus (CDV) virus. Animals infected with CDV lost most of their antibodies to influenza and had more severe disease than animals not previously infected with CDV when subsequently infected with influenza virus.
"The measles vaccine is not only important for protection against the measles virus, it also protects against the onset or severe progression of other infectious diseases. It protects the immune memory, which can be severely impaired in measles infections," said Prof. Klaus Cichutek, President of the Paul Ehrlich Institute.
Petrova VN, Sawatsky B, Han AX, Laksono BM, Walz L, Parker E, Pieper K, Anderson CA, de Vries RD, Lanzavecchia A, Kellam P, Messling V, de Swart RL, Russel CA (2019): Incomplete genetic reconstitution pool B cells to long-term immune suppression after measles.
Sci Immunol November 1 (Epub ahead of print).
Doi: 10.1126 / sciimmunol.aay6125