Aus­tralia at epi­cen­tre of virus test kit

The Weekend Australian - Travel - - Health - Leigh Day­ton Science Writer

UARANTINE of­fi­cials, sci­en­tists and doc­tors will soon have a new tool in their bat­tle against dan­ger­ous bugs — a quick and easy test able to de­tect all the so-called fla­viviruses, which cause se­ri­ous dis­eases such as dengue fever and Ja­panese en­cephali­tis.

Team leader Mark Gibbs says pathol­ogy lab­o­ra­to­ries world­wide will be able to run the test us­ing con­ven­tional DNA test­ing equip­ment as soon as de­tails are pub­lished. His col­league at the Univer­sity of Queens­land in Bris­bane, doc­toral stu­dent Sh­eryl Ma­her, is pre­par­ing a re­port of the work, a joint ef­fort of the Aus­tralian Na­tional Univer­sity, the Univer­sity of Queens­land, Bri­tain’s Ox­ford Univer­sity and the Aus­tralian Biose­cu­rity Co­op­er­a­tive Re­search Cen­tre.

Al­ready, quar­an­tine of­fi­cials in the Top End are in­ter­ested. ‘‘ If you come into Aus­tralia with dengue, they want to stop you in your tracks,’’ says Gibbs, a vi­rol­o­gist, ex­pert in bioin­for­mat­ics and Aus­tralian Re­search Coun­cil re­searcher at Can­berra’s ANU. ‘‘ And if you have an un­known fla­vivirus, they’re go­ing to want to bring in the men with the white biose­cu­rity suits.’’

Ex­ist­ing fla­vivirus tests are slow, of­ten un­re­li­able and un­able to de­tect all of the 53 known fla­vivirus species, let alone iden­tify un­known viruses fall­ing into the group, or genus. What’s more, doc­tors of­ten con­fuse signs of fla­vivirus in­fec­tion with sim­i­lar symp­toms of other com­mon in­fec­tions such as in­fluenza or sep­ti­caemia. If peo­ple have mild or sub­clin­i­cal symp­toms they may not seek treat­ment, not only po­ten­tially spread­ing the dis­ease but pos­si­bly re­sult­ing in a more se­vere ill­ness for them­selves.

‘‘ So early and ac­cu­rate di­ag­no­sis is very im­por­tant,’’ Gibbs says.

The approach taken by his team in­volved search­ing through 257 ver­sions of the genome, or full ge­netic com­ple­ment , of known fla­viviruses. They dis­cov­ered two stretches of ge­netic ma­te­rial that were the same in all those fla­viviruses.

Us­ing that in­for­ma­tion the sci­en­tists de­signed two ‘‘ primers’’, stretches of sin­glestranded DNA (RNA) that at­tach to RNA from a fla­vivirus but not to non-fla­vivirus RNA. They tested the primers on the known species, as well as on sam­ples of fla­viviruses col­lected 40 years ago which are now not de­tectable by any ex­ist­ing test.

Since the primers picked up all the fla­viviruses, Gibbs is con­fi­dent they will iden­tify any emerg­ing or pre­vi­ously uniden­ti­fied species in the group. As a re­sult, once lab­o­ra­to­ries have the se­quence of the primers — the ge­netic build­ing blocks of the primers — they’ll be able to de­tect all mem­bers of the group. Tech­ni­cians would use the primers in stan­dard poly­merase chain re­ac­tion tests like those reg­u­larly utilised in foren­sic DNA tests.

Gibbs, Ma­her and their co-work­ers de­cided to de­velop the fla­vivirus de­tec­tion test to help avert out­breaks of un­known viruses such as se­vere acute res­pi­ra­tory syn­drome (SARS). In 2003 that new and fright­en­ing dis­ease swept through Hong Kong, South-East Asia and China, even­tu­ally spread­ing to North Amer­ica and Europe. Strict quar­an­tine mea­sures kept SARS out of Aus­tralia.

‘‘ It took about a month and the ef­fort of sev­eral teams of re­searchers be­fore we knew what SARS was,’’ Gibbs re­calls. SARS was a coro­n­avirus, not a fla­vivirus as some sci­en­tists be­lieved. Still, the ex­pe­ri­ence high­lighted the crit­i­cal need for tests able to iden­tify new and po­ten­tially deadly viruses.

And fla­viviruses are at the top of the list, says Gibbs. Most come from an­i­mals and are ini­tially spread by in­sects. ‘‘ They may or may not be trans­mit­ted to hu­mans, but many in the group have been trans­mit­ted to peo­ple and some of them are very bad, in­deed.’’

Ac­cord­ing to Gibbs, his col­leagues at Ox­ford had dis­cov­ered pre­vi­ously un­known viruses on the Great Bar­rier Reef and are search­ing for new fla­viviruses in sam­ples col­lected from ticks and mos­qui­toes from around the world. ‘‘ We’re wait­ing to see what they are,’’ he said.

Re­search leader: Mark Gibbs

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