Immune protection due to pathogen stress during conception

Improved immune protection for children due to high levels of pathogen contamination at the time of conception

04/18/2014

According to the latest report from the Max Planck Institute for Demographic Research (MPIDR) in Rostock, if an infectious disease at the time of conception infects a child, it will later be more resistant to pathogens. The high level of pathogen exposure to which the parents are exposed apparently leads to a kind of natural protection in the cradle.

The researchers of the Max Planck Institute for Demographic Research were able to use the example „of deadly measles and smallpox epidemics in the Canadian province of Quebec in the 18th century“, show for the first time that the burden of pathogens at the time of conception has a significant impact on children's resistance to future infectious diseases. „ Children who were conceived there during the measles wave of 1714-15 died much less frequently at the onset of smallpox 15 years later than children who had been conceived before the measles“, reports the MPIDR. The results of the current study are published in the journal by MPIDR's Biodemographer Kai Willführ and Mikko Myrskylä of the London School of Economics and Political Science „PLOS ONE“ released.

Generation during the measles wave improves resistance to smallpox
The researchers write that the time of their birth for many of the children during the smallpox epidemic around the year 1730 about life or death decided. Because the „The probability of dying from smallpox was only one-seventh that of children conceived during the measles wave of 1714/15 „normal“ The probability of death of her siblings, who were conceived and born before the eruption of measles“, reports the Max Planck Institute. However, the children would have paid a high price for this. „The mortality of children, who were so resilient during smallpox, was three times as high as that of smallpox-susceptible siblings in the period between the disease waves of 1714/15 and 1730“, so the MPIDR on.

Parents pass on immune protection to their children
The current study proves „for the first time for humans, that parents can prepare their children for upcoming illnesses“, emphasized study author Willführ. Here is a so-called „functional trans-generational effect“, because the „Mechanism can not be purely genetic, nor is the resistance developed limited to individual pathogens.“ At the time of conception, the parents were exposed to an increased burden of measles, not only giving the children more protection against this one infection, but also, „The defense against pathogens apparently worked better in the next generation, even in the fight against other diseases such as the dangerous smallpox“, reports the Max Planck Institute. Willführ added that the children's immune system seems to be optimized for a high-burden world when the latter was high in conception. In a world with few pathogens, however, the child's immune system would then seem to have worked worse.

More than just an immunization
The researchers are confident that the observed effects were due to the pathogen load during conception because when the children were born, the measles wave was already over. „The measles can only have an incentive during the procreation and pregnancy phases, which the parents then transferred to the next generation“, explained Kai Willführ. However, it can not be assumed that the children have simply become immune. Although the mother could pass on her own immunization by antibodies to the offspring, which works during pregnancy on the placenta and after birth on the mother's milk, but protect this defense „only against the same disease, against which the mother was immune“, reports the MPIDR. In the current study, however, the children were particularly resistant to a completely different disease, namely smallpox.

Better understanding of the development of the defense system
As a database, the researchers used the information on births and deaths from copies of old church books, „which had led the historic population of the St. Lawrence Valley in the Canadian province of Quebec“, so the message of the MPIDR. The birth cohorts were studied from 1705 to 1724 and their mortality up to the year 1740, where it was the researchers for the first time possible to separate the mortality effects of various diseases, „as they individually tracked the life histories of the children individually and at the same time included the connection to the siblings.“ The results of the current study make a significant contribution to understanding the intergenerational development of the immune system. The way in which the information on the pathogen load is passed on at the time of conception, however, remains unclear. (Fp)