The Economist - USA (2019-08-17)

62 Science & technology The EconomistAugust 17th 2019

L

eopardsealsresembletheirterres-

trialnamesakesintwoways.They

havepolka-dotpelts.Andtheyarepow-

erful,generallysolitarycarnivoresthat

arequitecapableofkillinga human

beingif theysochoose—ashasindeed

happenedonce,in2003,whena British

marinebiologistwasthevictim.

Curiously,though,therehavealso

beenreportsofleopardsealsbehavingin

a friendlymannertowardspeople—

apparentlytryingtopresentgifts,inthe

formofprey,todivers.Untilnow,there

hasbeennoexplanationforthisphilan-

thropy.ButworkjustpublishedinPolar

BiologybyJamesRobbinsofPlymouth

University,inBritain,suggeststhatwhat

thesealsareactuallylookingforisa

diningpartner.

MrRobbinsandhisteamwerestudy-

ingleopardsealsinthewatersaround

SouthGeorgia,anislandintheSouthern

Ocean1,500kmfromthetipoftheAnt-

arcticpeninsula.Insteadofdiving,or

watchingfromships,theyuseddronesto

carryouttheirobservations.These

dronesrecordedhithertounobserved

behaviouronthepartoftheanimals.

First,belyingtheirsolitaryreputa-

tion,thesealscametogetheringroupsto

attackkingpenguins(twicethesizeof

thegentoopenguininthephotograph)

thatwereenteringtheseafroma rookery

ontheisland.Second,whena sealdid

catcha penguininthesecircumstancesit

wouldsometimesoffertoshareit witha

neighbourina wayreminiscentofdiv-

ers’talesofgiftgiving.Whatlookedlike

anaberrationmightthusbea normal

wayofbehaving.Butwhy?

MrRobbins’ssuggestionisthatshar-

inga penguinwitha neighbourmakesit

easiertoeat.A closelookatfootagethe

dronesrecordedshowsthatsealsinsuch

partnershipstakeit inturnstofeed.One

holdsthebirdtightinitsjawswhilethe

otherripsoffa chunkoffleshandswal-

lowsit.Thentheyswaproles.Bycon-

trast,fora lonesealtoreducea penguin

tobite-sizedchunksmeanswhipping

thepreyaroundinitsjawswithasmuch

forceasit canmuster,inordertotear

lumpsoffleshfreefromthecarcass.This

commonlyhappens,butisthoughttobe

extremelytiring.Better,therefore,tofind

a buddyandenjoya mealtogether.

P-P-Pickupa penguin

Animalbehaviour

Antarcticpredatorssharetheirsupper

N

ews aboutEbola, a viral disease that

kills up to 90% of those it infects, is

usually grim. The latest Ebola outbreak, in

the Democratic Republic of Congo, has

thus far killed nearly 1,900 people and

rages on. But on August 12th the grimness

lifted somewhat with the announcement

that two anti-Ebola treatments being test-

ed in the country have proved effective. If

administered when the first signs of infec-

tion appear, they boost survival rates to

about 90%.

The treatments in question employ

antibodies. These are special protein mole-

cules made by the immune system in re-

sponse to infection. They work by locking

onto specific parts of invading pathogens,

or of body cells infected by those patho-

gens—either gumming the target up and

disabling it or marking it for destruction by

other parts of the immune system. It is pos-

sible, however, to give the immune system

a helping hand by identifying suitable anti-

bodies in advance, manufacturing them in

bulk, and then injecting them into those

infected by the pathogenic target.

One of the successful treatments, code-

named regn-eb3, is a cocktail of three such

antibodies, mixed by Regeneron, an Amer-

ican biotechnology firm. The other,

mab114, is a single antibody developed by

America’s National Institute for Allergies

and Infectious Diseases. regn-eb3 and

mab114 were among four experimental

treatments tested in a randomised trial at

clinics in Congo. Based on preliminary re-

sults from 500 patients, an oversight com-

mittee led by the World Health Organisa-

tion concluded that the trial should be

stopped immediately, in order that the two

successful treatments could be made avail-

able to everyone.

Prompt use after infection is vital. Over-

all, 29% of those receiving regn-eb3 died.

But of people treated when their viral loads

were still low, only 6% succumbed. For

mab114 the numbers were 34% and 11% re-

spectively—superficially less good, but ac-

tually indistinguishable statistically from

the results for regn-eb3. Two other candi-

date treatments had significantly worse

figures than these, and were therefore re-

jected by the overseers.

Both regn-eb3 and mab114 have histor-

ies. Regeneron developed the former in

2016, in response to an Ebola epidemic in

west Africa in which 11,000 people died.

But that outbreak came to an end before the

treatment could make its way into clinics,

and until this year there had been no op-

portunity to test it. The story of mab114

goes back even further. Its pertinent anti-

body was isolated from a survivor of an epi-

demic of Ebola in Congo in 1995.

Both treatments will now be deployed

in the field—but, given the smallish size of

the trial that approved them, doctors will

be looking closely at their relative effica-

cies to determine whether, in light of more

data, one is actually better than the other.

Regardless of that, effective treatment will

surely help break the epidemic directly, by

stopping those cured from passing on the

virus. It may help indirectly, too. At the mo-

ment, those who have become infected,

seeing others go into clinics alive only to

leave in coffins, are understandably reluc-

tant to follow suit. That means they remain

in their homes and spread the illness to

others. The prospect of going to a clinic for

a cure will change this, and thus also help

to break the chain of transmission. 7

Two treatments for Ebola emerge from

a clinical trial in Africa

Ebola

Hope