Virus Weaves Itself into the DNA Transferred from Parents to Babies

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Virus Weaves Itself into the DNA Transferred from Parents to Babies

Effects of unique form of congenital infection unknown

9/2/2008

University of Rochester Medical Center

http://news.biocompare.com/newsstory.asp?id=242354

Parents expect to pass on their eye or hair color, their knobby knees

or their big feet to their children through their genes. But they

don't expect to pass on viruses through those same genes.

New research from the University of Rochester Medical Center shows

that some parents pass on the human herpes virus 6 (HHV-6) to their

children because it is integrated into their chromosomes. This is the

first time a virus has been shown to become part of the human DNA and

then get passed to subsequent generations. This unique mode of

congenital infection may be occurring in as many as 1 of every 116

newborns, and the long-term consequences for a child's development

and immune system are unknown.

" At this point, we know very little about the implications of this

type of infection, but the section of the chromosome into which the

virus appears to integrate is important to the maintenance of normal

immune function, " said Caroline Breese Hall, M.D., professor of

Pediatrics and Medicine at the University of Rochester Medical

Center, and author of the study which publishes in Pediatrics this

month. " With further study, we hope to discern whether this type of

infection affects children differently than children infected after

birth. "

HHV-6 causes roseola, an infection that is nearly universal by 3

years of age. The typical roseola syndrome produces several days and

up to a week of a high fever and may have variable other symptoms

including mild respiratory and gastrointestinal symptoms. With

roseola, just as the fever breaks, the child may briefly develop a

rash. A congenital infection of HHV-6 – or one that is present at

birth – produces high levels of virus in the body but scientists

(doctors) do not know whether it produces any developmental or immune

system problems.

Some congenital infections can cause serious problems in fetuses. If

a mother contracts cytomegalovirus (CMV) while pregnant, her fetus is

at risk of hearing or vision loss, developmental disabilities and

problems with the lungs, liver and spleen. Some of those health

problems don't show up until months or years after birth. HHV-6 virus

is a closely related virus to CMV, and the congenital infection rate

of CMV is similar to that of congenital HHV-6 – about 1 percent.

However, this research shows that a congenital HHV-6 infection

differs greatly from a congenital CMV infection in that it is often

integrated into the chromosomes of the baby rather than passed

through the placenta.

" This is the first time a herpes virus has been recognized to

integrate into the human genome. To think that it's actually a part

of us – that's really fascinating, " said Caserta, M.D.,

associate professor of Pediatrics at the University of Rochester

Medical Center and one of the paper's authors. " This opens up a whole

new realm of exploration. "

Of 254 children enrolled in this study between July 2003 and April

2007, 43 had congenital HHV-6 infections based on cord blood samples.

Of 211 children without congenital infection, 42 were children who

acquired an HHV-6 infection during the study. Of the infants who had

congenital infections, 86 percent of them (37) had the virus

integrated into their chromosomes. Only six of the congenitally

infected babies were infected by the mother through the placenta .

Children who had integrated HHV-6 had higher levels of virus in the

body than those who were infected through the placenta. HHV-6 DNA was

found in the hair of one parent of all children with integrated virus

with available parental samples (18 mothers and 11 fathers), which

means the children acquired the integrated infections through their

mother's egg or father's sperm at conception. The virus's DNA was not

found in hair samples of parents of children who were infected after

birth.

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This study is part of a series of ongoing studies on children with

HHV-6 infections at the University's Golisano Children's Hospital at

Strong. This study was funded by grants from the National Institute

of Child Health and Development and, in part, by grants from the

General Clinical Research Center, the National Center for Research

Resources, the National Institutes of Health and the HHV-6 Foundation.