16 December 2019
Viral Immunol. 2019 Dec 13. doi: 10.1089/vim.2019.0090. [Epub ahead of print] PMID: 31834852 doi.org/10.1089/vim.2019.0090
Ranjan V, Mishra A, Kesarwani A, Mohan KV, Lal SN, Puliyel J, Upadhyay P.
By Jacob Puliyel
Mothers with a past history of Chickenpox infection may transmit Chickenpox viral DNA to their babies during pregnancy thereby stimulating their immunity against this infection, says a new study.
This mother-to-child transfer of viral DNA may be responsible for the long-lasting protection against serious chickenpox infection seen during childhood, according to its findings reported in the prestigious peer-reviewed journal, Viral Immunology.
The novel findings will revolutionize the present day understanding of how babies are protected against infections like chickenpox in childhood.
Jacob Puliyel and colleagues from St Stephens Hospital studied 350 mothers and their new-born babies.
Chickenpox reactivation after surgical stress is known. Scientists have also demonstrated that the stress of space travel can induce subclinical reactivation of chickenpox in astronauts. "Subclinical reactivation of chickenpox, induced by the stress of pregnancy, is being reported for the first time," the authors say.
The present understanding is that mothers provide their babies protection against a variety of common infections, by transferring readymade antibodies to them. The protection to the baby lasts for 12 to 15 months. If the baby encounters the infection while it is partially protected by maternal antibodies, the illness is mild. The baby then develops their own, long-lasting immunity.
Puliyel and colleagues suggest that in the case of chickenpox, mothers develop subclinical viremia and the viral DNA is transferred to their babies. It is likely that in such cases, antibodies are developed actively in the foetus.
"Babies develop more long-lasting active immunity with the transfer of chickenpox DNA from mothers – more than the short-term passive protection provided by the transfer of readymade antibodies," the authors say.
In the absence of vaccines, chicken pox spreads easily in the population and repeated exposure to the virus acts like booster doses. The high antibody levels – much higher than that after vaccination - are passed to babies and it protects them. Vaccination on the other hand will reduce person to person spread of natural disease and the antibody titres are not boosted, and so there is little protection provided to the next generation.
According to the authors, the ‘Chickenpox parties’ held in countries like UK to get the children exposed to others with chickenpox was not necessarily a bad idea, as they get naturally infected in childhood, when the disease is typically mild and later in life they are likely to pass on protecting Chickenpox antibodies and DNA to their offspring.
The authors found antibody levels against chickenpox in new-born babies were often higher than that in mothers suggesting that the antibody was actively transported to the baby.
"These findings broaden our understanding of how man has evolved to coexist, survive and even thrive, with the microorganisms in the environment," the authors say adding that government disease control plans with vaccines -- for infections which are not considered lethal -- have a potential to disturb this equilibrium. "This needs to be factored-in when embarking on global disease eradication programmes," they caution
Final publication is available from Mary Ann Liebert, Inc., publishers http://dx.doi.org/[ doi: 10.1089/vim.2019.0090]”.
The self-archived article [Epub ahead of print] is available here in accordance with the agreement of the authors with the publishers who hold copyrights to the article