343
5354107815011060120
Origin11025960128101155195265304374
of1511596012870109
viruses1655596012862100155225280341396
Treatment2625596012878133195265304406468537576
of3235596012870110
viral3380596012863100154225263
diseases2902782012870110164226296351412467
1.____________________________.956115201287010517524631638545652559566673580587594510151085115512261295136514361505157516451715178518551925199520652101
A309111520128102
virus32261152012870109156226280
is3541115201283993
a36691152012863
biological37661152012870109179218288358397459522560
agent43611152012863131194263303
that46991152012838108171209
reproduces8511340012662125203265335413491553616669
inside15561338012839108164202272334
the19251338012840109171
cells21311338012862124163202257
of24221338012870117
livinghosts257413380128397714718725632729371340012678147201248303
.32401338012835
When331013380128132201263334
infected36791338012839110157218281320381452
by41651338012870140
a43391338012862
virus,44361338012871110158227281316
a47871338012862
host48841338012870140195233
cell51521338012862124162202
is5390134001263994
forcedto851152501264711718024230538212681523012839108
produce14121523012870117186256327389451
many189815230128109169240310
thousands22421523012839109180250305366437506561
of28371523012870118
identical29901523012837108171240278317379442480
copies35051523012863133202241303358
of38971523012870117
the40501523012839108171
original42541523012871118156226265335398436
virus,47241523012870110157226280316
at50751523012861100
an52111523012862131
extraordinary8511710012662133180242311381444522561638708771840
rate17271710012662131178240
.19691708012835
Unlike203717080128102171211249320383
most245517080128109177232271
living2762170801283777146185255325
things,31221708012839109147218287341377
viruses35321708012871110156227281343397
do39651708012871140
not41401708012871140178
have43541708012870132202265
cells46561710012662125163201256
that49481708012838108171209
divide8511895012678117188226305367
;12171893012839
new12921893012870131233
viruses15591893012870109156226280343396
are19911893012862108170
assembled21961893012862117171234343411450513583
in28151893012837108
the29581893012838108170
infected31631893012839109155217280319382451
host36481893012870140194234
cell.39171893012863124163201237
Over418818930128102171234281
2,00045031893012870105175245316
species48561895012655133195258296358412
of53041893012870117
viruses8512079012870110157226280343397
have12822079012871133202265
been15812079012870133195264
discovered.18812079012870108163225295365428474537606641
2.____________________________95624480128701051752463163854565255956667358058759451015108511551226129513651436150515751645171517851855192519952065
.A30572448012835136
virus32262448012870109156226280
consists35412448012862133202256296350389443
of40202448012870116
two41712448012839140210
or44152448012871118
three45682448012839108155218280
parts:48822448012870133180218273311
genes,8512634012870133202265319355
made124126340128109169239302
from1578263401284794164274
eitherDNA18842634012863102141211273320224026370126101202303
or25782637012670132
RNA274526370126102202303
,30482634012835
long31182634012839109179250
molecules340226340128109177216279341410450512566
that40052634012837108171209
carry42492634012863125172217287
the45702634012839109172
genetic47762634012870133203265304342405
information;8512819012839110157226273382442481521591661699
aprotein1586281901286216842821012678140209257319357434
coat21532821012663133203250
that24382819012839108171210
protects26822819012870118187226288350389443
the31612819012839108171
genes;33672819012870132202265318357
and37592819012863133202
some39972819012854123233293
viruses43252819012870109157227281344398
have47582819012870132202265
an50582819012862131
envelope8513006012662140211273311382459522
of14083006012670117
fat15603006012647116163
that17583004012838108171209
surrounds20023004012855124171218287358428497552
and25903004012862131201
protects28263004012870117186226288350389443
them33043004012839109172281
when361830040128101170233303
they39573004012839108171241
are42323004012862109171
not44383004012870141179
contained46533004012862131201240303341411473543
within85131890128101140179249288358
a12453189012862
host13413189012871140194234
cell.16103189012863125163201237
Viruses188131890128101140187256311374427
vary23443191012670141204273
in26533189012838108
shape27973189012853124186255318
from3150318901284794163272
the34553189012839109172
simplehelical366231890128559420427231137440723191012678140178218280349388
and44943191012671149227
icosahedral47563191012639102171225295374435513575644684
to8513375012839110
more99633750128109177224286
complex13183375012862132242309349412482
structures.1835337501285493139209271310381427489544580
Viruses244933750128102140186256310373427
are29113375012863109172
about31183375012862131200271309
10034633375012870140209
times3708337501283977186246301
smaller40453375012854165225264303366413
than44923375012839109172241
bacteria.47693375012870131194233295341380442477
3.____________________________95637440128701051752463163854565255956667358058759451015108511551226129513651436150515751645171517851855192519952065
.Viruses30573744012835136174220291346407462
spreadin3555374701265513319525832740539963744012839108
many414037440128109169239310
different44843744012871110157204265312374443483
ways.500237440128102163233286322
Plant8513930012878117180249288
viruses11733930012871110157226280343398
are16063930012863108170
often18113930012871117156219288
spread21343930012855124171233296365
from2535393001284693162271
plant28393930012870109172243281
to31563930012839108
plant32993930012871109172241280
by36133930012870144
insects37913930012839109164227289327381
and42083930012862132202
other44443930012870109180242289
organisms,47673930012870117187249319358413522575610
known8514115012870141210312382
asvectors1268411501286311614194118012670133195242311374428
.18474115012835
Some19174115012878148256318
viruses22704115012870109156227281343397
of27024115012871117
animals28554115012862131169279339378433
are33244115012862109171
spread35304115012854125171233296365
by39314115012870140
blood-sucking41044115012871110180250320369423493556625663734804
insects49444118012639117171234295342396
.53414115012835
Each8514300012886148210280
species11674300012854124186249287349403
of16054300012871117
virus17564300012870110156226280
relieson2072430201266212516420226532024264300012870140
aparticularmethod.2601430001286326984302012678148211257296358437474544606334043000128109169208279349419455
Influenza38304300012846115162201271334403465528
viruses43914300012871109156226281343397
are48234300012863109172
spread50304300012853123171232294363
through8514485012839110157226296366436
the13224485012839109171
air15284485012863100148
by17094485012870141
people18834485012871133203274313375
when229344850128102171233303
they26324485012837108170240
cough29054485012863133203274344
or32844485012870117
sneeze,34364485012854124186249311373408
noroviruses38784485012870141188257327366413482536599654
are45674485012863108170
transmitted4773448501283985147217271381417457496559628
by8514671012870141
the10254671012839109172
faecal-oral12324671012847110172234297334382451498561599
route,18664671012847117186225288323
contaminate22244673012662133211257327444482560630676739
hands,29984671012870133202272326361
food33944671012847117186257
and36874671012862131200
water.392346710128101163202264311346
Rotavirus43044671012894163201264334372420489544
is4883467101283893
often50104671012870117155218287
spread8514856012855125172234296366
by12514856012870141
direct14254856012871110157219282320
contact17804856012863131202241302365404
with221948560128102140178249
infected25044856012837108154216278317379448
children.29884856012862132171210280327389458494
Human351648560128102171281341411
Immuno-deficiency3963485601284715726833640647752559565770374380484390697510381108
Virus510548560128101139186256311
HIV,85150410128101148249283
is1170504101283893
transmitted1299504101283985148217272382418458497559629
during19625041012871140187226296366
sexual23635041012855117187256319358
contact27575041012860131200240301364403
and31955041012863132202
by34315041012870141
the36055041012839109172
exposureof3815504301266213321028033441347553743875041012870116
infected45745041012838109156218279318381450
blood.50585041012870110180250320355
4._____________________________.The9565411012870105175246316385456525595666735805875945101510851155122612951365143615051575164517151785185519251995206521352170225623262388
origins33795411012871117156225265334388
of38035411012870117
viruses39545411012870109157226280342396
is4386541101283992
unclear:45145411012870139202240303365412450
some49995411012855124234294
may85155960128109170242
have11265596012870132203266
evolvedfrom142755980126621332022413113734511914559601284793164272
plasmids—pieces22205596012870109172227337373444499639710748811873936989
of32425596012870117
DNA339555960128101201302
that37325596012839109172210
can39795596012862124193
move420855960128109176247310
between45525596012870132170272334396467
cells—50555596012863124163201256398
while85157810128101171210249312
others11985781012870108178241287342
may157657810128109169240
have18495781012870133203265
evolved21495781012862132202241311374443
from2627578101284794164273
bacteria.29335781012871133195235297343381444479
5._____________________________.Viral956615201287010517524631638545652559566673580587594510151085115512261295136514361505157516451715178518551925199520652135217022722310235624182458
infections34496152012839108156218279318357427497551
often40356152012871117156218287
cause43586152012862125193249311
disease47036152012870109164226288342405
in51436152012838108
humans8516337012870141250310381436
and13226337012863131202
animals,15606337012862131169279339378433468
however20636337012870141243304373436483
they25816337012838108170240
are28556337012862109171
usually30616337012870125196257296336406
eliminated35016337012862101140250287357420458521591
by41266337012870141
the43006337012839109172
immune45066337012839149257325395458
system.49996337012855125178218280391424
Examples8516522012886155218327395435497552
of14396522012870116
common15906522012862132242350418490
human21156522012871140250309380
diseases25306522012871110164227289343405460
caused30266522012862123193247310380
by34406522012870141
viruses36146522012871110157226281344397
include40476522012839108174212283352414
the44966522012839109172
common47036522012861132241349417488
cold,52266522012863133172242277
influenza,8516708012839110157195264327396459521556
chickenpox14436708012861132170233302365434504574644
and21226708012863133202
measles.236067080128109168231285325388441477
Many287167080128125188258328
serious32336708012854117163202272342397
diseases36646708012870109164226288342405459
such41586708012855124187256
as44496708012861116
AIDS460067080128102148249327
and49626708012862132202
hepatitis8516893012870133202265304342381420474
are13616893012862109171
caused15676893012862125194248310381
by19826893012870140
viruses.21566893012870109157226281344397433
Antibiotics262368930128102171210249319358428466506569622
have32806893012870132202265
no35796893012871140
effect37556893012862109156218279318
on41076893012870141
viruses,42826893012870109157226281344397433
but47496893012870140178
antiviral49636893012862132171209280318365428466
drugs8517077012870117188257311
have11987077012870132202264
been14967077012870133195265
developed17967077012870132202265303373443506575
to24067077012839109
treat2550707701283986147210249
life-threatening2834707701283877124186235273344391452513552615684723793863
infections.37327077012839108156218280318358427497552588
Vaccines435470770128102162224287326396458512
that49017077012841111173211
produce8517263012870117188257327390452
lifelong1338726301283877124186225294365434
immunity18087263012837147255325396434474544
can23867263012862124195
prevent26147263012871118180249312382421
some30707263012855124233294
viral33997263012870109157219258
infections.36937263012837107154216279317356426495550586
3.8517639012670106
Translate9917639012686140211289343381452490553
the15797639012639116179
1st17937639012670186476080813560
passage19597639012669138193248317388451
into24457639012637116155224
Russian.27057639012693172225280318388466501