Study finds mechanism for mother-child transmission of immunity to chickenpox

Health news

New Delhi, December 20: A new study has
found that women who have had Chickenpox infection may transmit the DNA of the disease-causing
virus to their babies during pregnancy, thus
stimulating their immunity against the infection and protecting them. 

This mother-to-child transfer of
viral DNA
may be responsible for the long-lasting protection against
chickenpox infection seen during childhood, said researchers from the National
Institute of Immunology and St Stephens Hospital, Delhi, said in their study published
in journal Viral Immunology.

The new finding takes the understanding on
how babies are protected against infections like chickenpox to a new level. Presently,
it is understood that mothers provide babies protection against a variety
of common infections by transferring readymade antibodies to them, that the
protection lasts for 12 to 15 months and that if a baby encounters an infection
during this period, it gets ill in a mild form and develops its own
long-lasting immunity for that disease.

The new study led by Dr. Jacob Puliyel
from St Stephens Hospital has shown that it was, however, different in the case
of chickenpox. The scientists found that the mothers develop subclinical
viremia and the viral DNA is transferred to their babies. The study was done in
350 mothers and their newborn babies.

The researchers said,

“the babies of mothers, who had
chickenpox earlier in their life, develop a long-lasting active immunity with
the transfer of chickenpox DNA from mothers, instead of the short-term passive
protection provided by the transfer of readymade antibodies. It is likely that
the antibodies are developed actively in the foetus”.

They also noted,

“several studies have already shown that
Chickenpox can get reactivated due to stress following surgeries and space
travel. But, subclinical reactivation of chickenpox, induced by the stress of
pregnancy, is being reported for the first time.” 

 Further, they said that the ‘chickenpox
parties’ held in countries like UK to get 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 said that in the wake of the new
finding, there may be a need to review of vaccination policies for chickenpox.

The study was supported by a core grant from the Department of Biotechnology (DBT) to National Institute of Immunology, New Delhi.  Besides Dr. Puliyel, the team consisted of Alaknanda Mishra, Ashwani Kesarwani, K. Varsha Mohan and Pramod Upadhyay, of National Institute of Immunology and Vivek Ranjan, and Sandeep Narayan Lal, of St Stephens Hospital.

By Sunderarajan Padmanabhan