Re­searchers re­port how Zika virus in­fects de­vel­op­ing brain

Iran Daily - - Health -

An in­ter­na­tional re­search team re­ported that the Zika virus is trans­mit­ted from mother to her fe­tus by in­fected cells that will later de­velop into the brain’s first and pri­mary form of de­fense against in­va­sive pathogens.

The dis­cov­ery, de­tailed in a study pub­lished in the cur­rent on­line is­sue of Hu­man Molec­u­lar Ge­net­ics, may open a path­way for a po­ten­tial treat­ment for in­fected pa­tients, xin­huanet. com wrote.

Alysson Muotri, a pro­fes­sor at the Uni­ver­sity of Cal­i­for­nia San Diego School of Medicine, said, “It’s a Tro­jan Horse strat­egy.”

She said that dur­ing em­bryo­ge­n­e­sis, the early stages of pre­na­tal de­vel­op­ment, cells called mi­croglia form in the yolk sac and then dis­perse through­out the cen­tral ner­vous sys­tem (CNS) of the de­vel­op­ing child.

In the brain, these mi­croglia con­stantly clears away plaques, dam­aged cells and in­fec­tious agents.

Muotri said, “The Zika virus can in­fect the early mi­croglia, sneak­ing into the brain where they trans­mit the virus to other brain cells, re­sult­ing in the dev­as­tat­ing neu­ro­log­i­cal dam­age we see in some new­borns.”

Be­gin­ning in 2015, a dra­matic in­crease in chil­dren born with mi­cro­cephaly, a con­di­tion in which their heads are smaller than nor­mal, and other birth de­fects were ob­served in Brazil.

The phe­nom­e­non was sub­se­quently linked to in­fec­tion by the Zika virus, which Muotri and oth­ers con­firmed last year caused birth de­fects in ex­per­i­men­tal mod­els.

The Zika virus is spread from Aedes species mos­qui­toes to hu­mans in trop­i­cal re­gions, but the method of trans­mis­sion from a preg­nant mother to her un­born child, though sci­en­tists have not been able to pre­cisely describe the mode of trans­mis­sion.

Muotri said, “Con­sid­er­ing the tim­ing of trans­mis­sion, we hy­poth­e­sized that mi­croglia might be serv­ing as a Tro­jan horse to trans­port the virus dur­ing in­va­sion of the CNS.”

To test their hy­poth­e­sis, re­searchers at the Uni­ver­sity of Cal­i­for­nia San Diego School of Medicine, with col­leagues in Brazil used hu­man in­duced pluripo­tent stem cells to cre­ate two rel­e­vant CNS cell types: Mi­croglia and neu­ral pro­gen­i­tor cells (NPCS), which gen­er­ate the mil­lions of neu­rons and glial cells re­quired dur­ing em­bry­onic de­vel­op­ment.

Then they es­tab­lished a co­cul­ture sys­tem that mim­icked the in­ter­ac­tions of the two cell types in vitro when ex­posed to the Zika virus.

Ac­cord­ing to the new study, the mi­croglia cells en­gulfed Zika-in­fected NPCS, do­ing their job.

But when these mi­croglia car­ry­ing the virus were placed in con­tact with non-in­fected NPCS, they trans­mit­ted the virus to the lat­ter.

The sci­en­tists also tested a drug called So­fos­bu­vir, mar­keted as So­valdi and used to treat hep­ati­tis C, and found it ‘sig­nif­i­cantly de­creased cell death of NPCS and the vi­ral load in NPCS’.

Muotri said that they were en­cour­ag­ing, sug­gest­ing mi­croglial cells could be a ther­a­peu­tic tar­get for re­duc­ing Zika trans­mis­sion into the CNS of de­vel­op­ing fe­tuses.

Though the find­ings are based on in vitro re­search, more in­ves­ti­ga­tion is needed.

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