prawf newydd yn defnyddio diferyn unigol o waed i ddatgelu hanes gyfan o heintiau firaol

New test uses a single drop of blood to reveal entire history of viral infections

 

Powered by Guardian.co.ukMae'r erthygl hon yn dwyn y teitl “prawf newydd yn defnyddio diferyn unigol o waed i ddatgelu hanes gyfan o heintiau firaol” ei ysgrifennu gan Ian Sampl golygydd Gwyddoniaeth, ar gyfer The Guardian ar ddydd Iau 4 Mehefin 2015 18.00 UTC

Mae ymchwilwyr wedi datblygu prawf rhad a chyflym sy'n datgelu hanes llawn yr unigolyn o heintiau firaol o diferyn o waed sengl.

Mae'r prawf yn galluogi meddygon i ddarllen rhestr o'r firysau sydd wedi heintio, neu barhau i heintio, cleifion hyd yn oed pan nad ydynt wedi achosi unrhyw symptomau amlwg.

Mae'r dechnoleg yn golygu y gallai meddygon teulu sgrinio cleifion ar gyfer pob un o'r firysau sy'n gallu heintio pobl. Gallai drawsnewid y ganfod heintiau difrifol megis hepatitis C a HIV, y gall pobl cario am flynyddoedd heb wybod.

"Fel arfer, pan fydd meddyg eisiau gwybod os oes rhywun wedi bod yn heintio â firws, rhaid iddynt ddyfalu beth mae'r feirws yn ei, ac yna edrych yn benodol ar gyfer y feirws,"Meddai Stephen Elledge, a arweiniodd y prosiect yn Ysbyty Brigham a Merched yn Boston.

"Gallai hyn arwain at diagnostig lle mae pobl yn mynd yn flynyddol at eu meddyg ac yn cael eu hanes firaol a gofnodwyd. Gallai sicr ddarganfod heintiau firaol sy'n ddifrifol ac nad yw claf yn gwybod eu bod wedi,"Meddai.

Y (£ 16) prawf yn tynnu ar ddatblygiadau mewn bioleg synthetig a dilyniannu genyn gyflym i ddadansoddi mwy na 1000 mathau o firysau dynol mewn un tocyn. Hyd yn hyn, rhan fwyaf o brofion wedi edrych dim ond am feirws un ar y tro. Elledge yn amcangyfrif bod y prawf diweddaraf, gelwir VirScan, gall prosesu 100 samplau mewn dau neu dri diwrnod.

Mae'r prawf yn manteisio ar y ffaith bod y system imiwnedd yn gwneud gwrthgyrff i ymladd firysau pryd bynnag y corff yn cael ei heintio. Gall y rhain gwrthgyrff byw yn y llif gwaed am flynyddoedd a hyd yn oed degawdau.

I ddatblygu'r prawf, Elledge peiriannu sypiau o firysau ddiniwed i gario darnau o broteinau rhag firysau dynol ar eu arwynebau. yn gyfan gwbl, maent yn ei proteinau o fwy nag 1000 straen y 206 mathau o firysau hysbys i heintio pobl. Gwrthgyrff yn defnyddio darnau protein hyn i gydnabod goresgynnol firysau a lansio eu ymosodiadau.

Pan fydd defnyn o waed o claf yn cael ei gymysgu gyda'r firysau a addaswyd, unrhyw wrthgyrff sydd ganddynt gydio ynddo i proteinau firws dynol maent yn cydnabod fel goresgynwyr. The scientists then pull out the antibodies and identify the human viruses from the protein fragments they have stuck to.

“It’s the first time we’ve been able to look in a completely unbiased manner at what viruses are infecting people, and we can do it for all known viruses,” said Elledge. The test picks up the antibodies a person produces from vaccinations, but these can be discarded from the test results. Details are reported in the journal Gwyddoniaeth.

In a demonstration of the technology, the team analysed blood from 569 people in the US, De Affrica, Thailand and Peru. The test found that, ar gyfartaledd, people had been infected with 10 species of viruses, though at least two people in the trial had histories of 84 infections from different kinds of viruses.

The most common infections were herpes viruses, which cause cold sores, enteroviruses that upset stomaches, influenza, and rhinoviruses that trigger common colds. Those in the US had experienced fewer infections than those in the other countries, and as expected, older people had richer viral histories than youngsters.

The test could bring about major benefits for organ transplant patients. One problem that can follow transplant surgery is the unexpected reawakening of viruses that have lurked inactive in the patient or donor for years. These viruses can return in force when the patient’s immune system is suppressed with drugs to prevent them rejecting the organ. Standard tests often fail to pick up latent viruses before surgery, but the VirScan procedure could reveal their presence and alert doctors and patients to the danger.

“This could be very valuable,” said Iwijn De Vlaminck, a biomedical engineer at Cornell University in New York, who was not involved in the study. “What this allows you to do is look into the past and measure a person’s exposure to previous infections. That has important advantages, because you can detect these infections that go to latency. You could screen blood from patients and organ donors in this very broad manner and predict potential future issues with viral reactivation.”

Scientists believe the test will also cast light on how certain viral infections can predispose people to seemingly unrelated diseases later in life. Some infections can cause permanent damage to body tissues, or alter the immune system, in ways that leave people more at risk of medical problems when they are older. Er enghraifft,, infection with Epstein-Barr virus can raise the risk of cancer. But how other viruses affect long term health is far murkier. “That kind of analysis is something this really makes possible,” said Elledge.

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