The Economist - USA (2021-11-13)

The Economist November 13th 2021 Science & technology 83

disease­causing  microbes  off  theirleaves,
support  them  in  collecting  nitrogenfrom
the  environment  and  help  themdissolve
minerals found in the soil. 
Knowing  all  this,  Virgilija Gaveliene
and  Sigita  Jurkoniene,  of  the  Instituteof
Botany  Nature  Research  CentreinLithua­
nia, set out to find a way to use probiotics
to  boost  the  yield  of  blackcurrantbushes,
which  are  grown  in  that  country.There­
searchers also knew from otherworkthat
the  production  of  strawberriesandrasp­
berries  could  be  increased  by exposing
plants to a carefully selected mixofbacte­
ria  from  families  like  Bacillus,  Acinetobac-
terand  Pseduomona.  And  they  wereaware
of  preliminary  evidence  that  probiotics
had the potential to enhance productionof
certain  antioxidants,  like  anthocyanins
and flavonoids.
Working with colleagues, theysetupan
experiment. Four blackcurrant fields,each
one hectare in size, were exposedtodiffer­
ent  probiotic  treatments.  Thesewereap­
plied  first  when  shoots  were  juststarting
to grow and then again as buds werebegin­
ning to flower. One field was sprayedwitha
mix  of  bacteria  that  the  teamsuspected
would improve growth and yield.Another
field was sprayed with a mix of organicfer­
tilisers  and  bacteria  that  the  researchers
expected  would  enhance  the chemical
composition  of  the  berries  andimprove
their nutrient content. The thirdfieldwas
sprayed  with  both  mixtures  while the
fourth was left as a control and sprayedon­
ly  with  water.  After  the  harvest,theteam
measured  the  biomass  of  the freshly
picked berries and studied their chemistry.
As  they  report  in  Agricultural Science
and Technology,  the  results  wereimpres­
sive.  While  a  thousand  blackcurrantscol­
lected  at  random  from  the  controlplot
weighed  just  over  538  grams, the same
number  from  the  field  exposed to both
treatments  weighed  nearly  783grams.A
similar increase was also true forthefield
sprayed with the yield­enhancingbacteria.
The  team  were,  however,  concerned
that enhanced berry growth mightbecom­
ing at a cost of less antioxidant. Tothisend,
their analysis showed that exposuretoei­
ther of the probiotic mixtures ontheirown
did  significantly  lower  blackcurrantanti­
oxidant  activity  from  the  controllevelof
73%  to  65%  and  60%.  Only  exposureto
both probiotic mixtures allowedblackcur­
rant  growth  to  be  enhanced  whilemain­
taining  a  statistically  identical level of
antioxidant activity of 72.7%
All  told,  Drs  Jurkoniene  andGaveliene
are convinced that the right mix ofbacteria
can  help  blackcurrant  farmers meetde­
mand  without  using  chemicals. And it
could help other growers. Whatworksfor
berries  should,  in  theory,  workforother
fruit, like apples, pears and oranges. More
experiments are needed to be sure.n

Covid-19

Pills with promise

T

helatestnewsinthefightagainstco­

vid­19isencouraging.Twonewantivi­

raldrugshavebeendeemedsoeffective

thatclinicaltrialsendedearly.Datafrom

thesetrialshavenotyetbeenpublished.

However,regulatorsaremovingswiftly to

considergeneraluseofthedrugs.Theywill

filla largegapinthetoolkitdoctorsareus­

ingtofightthevirus,andcouldwellhelp

endtheglobalpandemic.

Thenewdrugsaremolnupiravir(Lagev­

rio),developedbyMerck,a pharmaceutical

company,workingwithRidgebackBiothe­

rapeutics, a biotech firm, andPaxlovid,

whichwasdevelopedbyPfizer.Allthree

areAmerican companies.Thosemostat

riskfromtheseriouseffectsofcovidarefar

lesslikelytobehospitalised,ordie,ifthey

takea courseofeitherofthesepillsinthe

fivedaysaftersymptomsfirstappear.

MercksaidinOctoberthatmolnupira­

virreducedtheriskofhospitalisationor

deathbyabouthalf,whengiventopatients

withoneriskfactorforcovid,suchasobe­

sityorheartdisease.RegulatorsinAmeri­

ca,EuropeandattheWorldHealthOrgani­

sationareassessingthedrug.Britainhas

approveditandwillstartusingthetreat­

mentnextmonth.OnNovember5thPfizer

saiditspillreducedtheriskofhospitalisa­

tionordeathby89%iftakenwithinthree

days.(Infact,duringitstrialnopatient

diedatallwhentakingPaxlovidwithinfive

daysofsymptoms.)

Molnupiraviriswhatisknownasa pro­

drug,whichmeansthatit isconvertedinto

its active form when it arrives inside cells.

Once  there,  it  is  incorporated  into  the  ge­

netic material of the virus whereby it dis­

rupts  its  ability  to  replicate.  Errors  accu­

mulate  in  the  virus’s  genetic  material,  a

process  known  as  “error  catastrophe”.

Trials in animals have raised concerns that

the  drug  might  pose  risks  to  unborn  chil­

dren, hence the British government has ad­

vised  against  its  use  during  pregnancy,  or

while breastfeeding. Other regulators may

issue similar warnings. 

Paxlovid is in fact a combination of two

drugs:  an  existing  one  called  ritonavir,

which  is  given  alongside  a  novel  protease

inhibitor known as PF­07321332. The prote­

ase  inhibitor  was  designed  to  bind  and

block the protease enzymes that sars­cov­2

uses  to  replicate.  Ritonavir  prevents  the

protease  inhibitor  from  being  broken

down too quickly in the body. 

Molnupiravir  and  Paxlovid  are  also

known  as  “small  molecule”  drugs.  These

are  molecules  that  are  easy  to  make.  Both

firms say the price of the drugs will vary ac­

cording to the wealth of the nation buying

them. That will likely mean that rich coun­

tries will pay $700 for a five­day course of

pills, while poorer ones might pay around

$20,  and  maybe  less  as  the  cost  of  manu­

facturing comes down. 

Although both firms have said they in­

tend to make these drugs widely accessible

around  the  world,  Merck  already  has  an

edge.  It  has  signed  a  number  of  licences

which  allow  other  manufacturers  to  pro­

duce the drug, and it has reserved 3m doses

for  low­  and  middle­income  countries.

This is to ensure that rich countries do not

monopolise  the  supply  of  the  new  medi­

cines as they have done for vaccines. Merck

expects  to  make  10m  doses  this  year,  and

20m next year. Generic manufacturers will

make many more. Pfizer, which has not yet

received any regulatory authorisations, ex­

pects 180,000 packs of pills to be produced

by the end of this year, and 21m in the first

half of 2022.  

These drugs herald a second big turning

point in the pandemic (the first being vac­

cines). Rising case numbers across Europe

suggest  there  will  be  a  strong  demand  for

such medicines to keep people out of hos­

pital.  While  patients  wait  for  them  to  ar­

rive,  it  is  also  possible  that  doctors  might

consider  the  use  of  fluvoxamine,  an  anti­

depressant medicine which also appears to

lower the risks from covid. 

As the new treatments roll out for use,

there  will  be  concern  among  some  scien­

tists  and  doctors  about  the  virus  develop­

ing  resistance,  particularly  if  patients  do

not  complete  their  course.  Keeping  one

step ahead of sars­cov­2 will require plan­

ning  for  such  an  eventuality.  That  means

deducing which antiviral drugscanbe giv­

en in combinations to create atherapy that

the virus will struggle to defeat.n

New antiviral drugs appear highly

effective at fighting the disease

Apill is coming to help