Sci­ence’s bid to en­gi­neer Zika away

Among the trial meth­ods: ge­netic en­gi­neer­ing, ra­di­a­tion, lar­vi­cide “We don’t re­ally have any method that’s work­ing”

Bloomberg Businessweek (Asia) - - GLOBAL ECONOMICS -

Un­til there’s a vac­cine or treat­ment for the Zika virus, the quick­est way to con­trol its spread is to at­tack the mos­qui­toes that carry it. Biotech com­pa­nies and gov­ern­ments are wield­ing their best weapons, all of which in­volve breed­ing the blood­suck­ers in labs and ap­ply­ing treat­ments that ren­der them un­able to re­pro­duce or spread viruses, then re­leas­ing them into the wild.

In Brazil, Ox­itec says it ex­pects ap­proval within weeks to sell the govern­ment a bio­engi­neered mos­quito in­ca­pable of hav­ing off­spring. If there are enough ster­ile mos­qui­toes in the mat­ing pool, fewer new ones will be born. Ox­itec, a Bri­tish sub­sidiary of U.S. biotech com­pany In­trexon, has con­ducted tri­als in South Amer­ica since 2009 and al­ready has a fa­cil­ity in Brazil that can breed 2 mil­lion ge­net­i­cally mod­i­fied (GM) mos­qui­toes in a week. “We’re very much op­er­a­tional,” says Chief Ex­ec­u­tive Of­fi­cer Ha­dyn Parry.

The United Na­tions In­ter­na­tional Atomic En­ergy Agency has of­fered to show Brazil­ian au­thor­i­ties how to ster­il­ize male mos­qui­toes with ra­di­a­tion. The tech­nique is widely used to con­trol agri­cul­tural pests. Aus­tralian sci­en­tists say they might be able to block trans­mis­sion of Zika by in­fect­ing mos­qui­toes with a nat­u­rally oc­cur­ring bac­terium. And Mosquit­o­Mate, a Lex­ing­ton, Ky.-based startup, is ex­per­i­ment­ing with a way to dust the bugs with a hor­mone-based lar­vi­cide.

Th­ese strate­gies mark a sharp de­par­ture from the old pes­ti­cide­cen­tric method of “spray-’n’-pray.” So far, “we don’t re­ally have any method that’s work­ing,” says Paul Re­iter, a con­sul­tant on in­sect-borne dis­ease who’s worked at France’s In­sti­tut Pas­teur and the U.S. Cen­ters for Dis­ease Con­trol and Preven­tion.

Mos­qui­toes have de­vel­oped re­sis­tance to DDT and many of the syn­thetic pyrethroid com­pounds used to treat mos­quito nets. The Aedes ae­gypti mos­quito, which spreads Zika and dengue fever, is rapidly pro­lif­er­at­ing in trop­i­cal cities, where it can breed in show­ers, toi­let tanks—even in dis­carded bot­tle caps. The World Health Or­ga­ni­za­tion, de­scrib­ing A. ae­gypti as “an op­por­tunis­tic and te­na­cious men­ace,” on Feb. 16 urged coun­tries “to boost the use of both old and new ap­proaches to mos­quito con­trol.”

Ox­itec says it’s ready­ing a Brazil­ian fac­tory to pro­duce 60 mil­lion GM mos­qui­toes a week, but that would cover an area with only about 60,000 peo­ple. While the Bri­tish com­pany won’t dis­close con­struc­tion costs, they could eas­ily run into the tens of mil­lions of dol­lars. A decade ago, it cost $8.4 mil­lion to build a fa­cil­ity in Brazil ca­pa­ble of breed­ing and ir­ra­di­at­ing 200 mil­lion Mediter­ranean fruit flies weekly, ac­cord­ing to a 2011 study pub­lished by Ox­itec sci­en­tists. The breed­ing fa­cil­i­ties for the other treat­ment meth­ods have sim­i­lar re­quire­ments.

In­tro­duc­ing treated mos­qui­toes into the gen­eral pop­u­la­tion presents spe­cial chal­lenges. They’re too frag­ile to

drop from planes. Ox­itec will use trucks to spread its ge­net­i­cally mod­i­fied in­sects. The UN is work­ing with a Ger­man com­pany to de­velop de­liv­ery by drone.

Once the mos­qui­toes reach their desti­na­tion, though, they’ll be­gin an­ni­hi­lat­ing them­selves, and that’s a big ad­van­tage, says Mosquit­o­Mate founder and CEO Stephen Dob­son, an en­to­mol­ogy pro­fes­sor at the Univer­sity of Ken­tucky. Says Dob­son: “We let the mos­qui­toes do the work for us.” −Carol Mat­lack, with Ja­son Gale and Jonathan Tirone

The bot­tom line Sev­eral new anti-mos­quito treat­ments seek to in­tro­duce lab-bred bugs that can’t re­pro­duce or trans­mit viruses.

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