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KHOA HOC KY THUAT T H O Y TAP XXI SO 1 - 2014
i0Sl)iln cifu fefipa toe DANH GlA HIEU llfC CUA UACXIN AMERVAC
PRRS
001 VOll CHUNG VIRUS PRRS GAY RENH DONG llfC CAO A VIET NAM To
Long Thanh', Nguyen Hoang Bang', Tdng HS-u Hien',
Bach Qudc Thdng', Daniel Torrent^
TOM TAT Dung vacxin AMERVAC PRRS khdo nghiem tren Ion k6t qua
cho thiy nhu sau: Vacxin nhu^c
doc AMERVAC PRRS do hSng Laboratorios HIPRA, S.A san xuit dam
bao an toan khi su dung. Vims vacxin khong truyen ngang tir 16 thi
nghiem sang 16 doi chung va c6 tac dung kich thich sinh dap ung
mien dich khi Ion bi nhiem virus cuong doc va cho dap iing mien
dich se manh hon. Dap ung mien dich do vacxin tao ra co tac dung
lam giam muc dp tram trpng ciia benh khi cong voi 2 chung virus
PRRS cuong doc ciia Viet Nam thong qua kiem tra benh tich dai the
va vi the tren cac ca quan npi tang, dac biet la a phoi. Lo diing
vacxin ciing tang trpng hon so voi 16 khong dimg vacxin khi cong
cudng dpe. Dap ung mien dich co dupc nha vacxin da loai bo hoan
toan virus trong ca the Ipn v^o khoang 2-3 tuan sau khi bi
nhiem.
Tir khoa: Lan, PRRS, vacxin PRRS, khao nghiem, cong cuong
dpe
Evaluation of efficiency of Amervac PRRS vaccine for the High
virulent, pathologenic virus strain in Viet Nam
To Long Thanh, Nguyen Hoang Dang, Tong Huu Hien, Bach Quoc
Thang, Daniel Torrents
SUMI\/IARY Live AMERVAC PRRS vaccine produced by HIPRA
Laboratory, SA (Spain) was used for
testing on pigs raising in Viet Nam The tested result indicated
that this vaccine was safe in use. Vaccine virus did not transmit
horizontally from experimental pigs to control pigs and had the
effect in inducing immune response at higher level when the pig was
Infected with challenge virus. Immune response induced by vaccine
had the effect in reducing the serious level of disease when
challenge with 2 virus strains of Viet Nam. This result showed
clearly when testing the gross and histobiological lesions in
internal organs (particularly is lung). The vaccinated pigs also
increased higher body weight compared to the control pigs when
applying challenge test. Immune response induced by vaccinating
AMERVAC PRRS vaccine had removed the entire of virus In pigs in 2-3
weeks after pigs were infected with PRRS.
Key words: Pig, PRRS, PRRS vaccine, Testing, Challenge test
' Trung tam chan doan thii y Trung uong ' Cong ly thii y xanh ^
Cong ty Hipra S.A, Amer Tay Ban Nha
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
I. DAT VAN DE Hpi chung roi loan sinh san va ho hap ciia
Ign (PRRS) th8 doc luc cao do virus PRRS (PRRSV) thuoc genotype
II gay ra. The benh nay xuat hien tai Viet Nam nam 2007 va da gay
nen nhung t6n thSt kinh t6 nang ne cho nhirng nguai chan nuoi lan
trong nhiing nam sau do.
Ve lich sir, PRRSV genotype 1 xuat hien lan dSu tien tai Ha Lan
nam 1986, gay nen PRRS the kinh din hay con gpi la PRRS the doc luc
thap da tham nhap vao Viet Nam tir cuoi nam 1996 dau nam 1997.
Nhirng nam sau do, mpt s6 loai vacxin, trong do c6 vacxin AMERVAC
PRRS da dupc dang ky sir dung tai Viet Nam. Vacxin AMERVAC PRRS la
vacxin genotype I da duac su dung ke tir khi dang ky tu nam 2005
cho den nay.
Viec sir dung rpng rai vacxin AMERVAC PRRS (genotype I) d phong
ch6ng PRRS thd doc luc cao (genotype II) tai cac dia phuang doi hoi
viec danh gia kha nang bao hp ciia loai vacxin nay vai chung PRRSV
the doc luc cao dang liru hanh tai Viet Nam. Day cung chinh la muc
dich cua bai bao nay.
IL NGUYEN LIEU VA PHU'CTNG PHAP NGHIEN ClTU 2.1. Nguyfin v3t
lieu
- Dpng vat thi nghiem: Chpn 16 lan con 4 tuan tuoi, khoe manh va
am tinh vdi virus PRRS, khong hem bdt ky mot loai vacxin phong PRRS
nao. Lan duac nuoi va tien hanh thuc nghiem tai Trung tam chan doan
thii y TW.
- Vacxin nhupc doc AMERVAC PRRS do hang Laboratorios HIPRA, S.A
san xuat, dung cho lan 3 tuan tuoi tro len.
Virus cuong doc gom 2 chung: Chiing virus PRRS so 21 do cong ty
HIPRA cung cap CO ngu6n goe tir Viet Nam nam 2008 va chiing vims
PRRS ky hieu VN07196 cua Trung tam chan doan thii y TW.
- Kit ELlSAphat hien khang thi PRRS
- Kit chiet tach Qiagen RNeasy, kit nhan gen Invitrogen SSIII
One-step qRT-PCR system (Cat 11732-020).
- Cac hoa chat va nguyen lieu can thiet khac.
2.2. Phucmg ph^p nghien ciru - Bo tri thi nghiem:
% a i livti ^ a p l m o n g i>li:'ip t h i ii)?;lii
I 1 i l
" " "
E"::;"!" . . n . , . F^ HSil \ .i..D*,.CM.
*_^_^_ ,M ' " I T " " '*i-^ ':^ ^"^r-'-
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KHOA HQC K? THUAT THO Y TAP XXI S6 1 - 2014
Theo d5i Ipn sau khi tidm vacxin d^ danh gia tinh an toan, bieu
hi?n iam sang \k bi^n ddi than nhi?t tir ngay diij 32 dgn 46. Can
Ipn, theo d5i trpng lupng vao cac ngay thir 0, 32, 39, 36 va 55.
LSy mau vao cac ngay thu 29,35, 39,42,46 va 55 d6 xet nghi?m ham
lupng virus huy6t. Xet nghi?m khang th6 khang virus PRRS vao cac
ngay thu 0, 29 va 55. M6 kham kigm tra benh tich, cham diem phoi
tit ca Ipn vao ngay thijr 55.
2.3. Cdc phinmg phdp xit nghl|in - Diing phuang phdp ELISA va
IPMA d6
kiim tra khang thS.
- Dimg phuang phap Real-time RT-PCR d8 kiem tra virus.
- Dung phuang phap m6 kham va lam tiSu bdn vi thi de kiem tra
b8nh tich dai th8 va vi thi.
- Phuang phdp ddnh gia an toan ciia vacxin: Theo doi mpt tudn
sau khi tiem vacxin, nlu khong CO phdn irng bat thuong nhu: mSt
moi, chdn ho^c b6 dn, tdng than nhi?t vd cdc dau hieu b?nh 1^ khdc
Id an toan.
- Phuang phdp ddnh gid hi$u luc ciia vacxin: Hi^n tai, Vi?t Nam
chua c6 chting virus PRRS c6 khd ndng gay chit 100% Ipn man cam nen
vi^c ddnh gid hi?u qua cua vacxin PRRS can phai kit hpp giiJa chi
d6u bao hp sau khi cong
cuong dpe voi cdc chi tieu khac bao g6m: Bilu hien lam sang,
tang than nhiet, benh dch dai the, vi the a ph6i, tinh trang nhilm
virus mau va kiem tra dap irng mien dich bdng phucmg phdp huylt
thanh hoc.
I I I . K E T Q U A VA T H A O L U A N 3.1 Ket qua theo doi an
tokn sau khi tiSm vacxin
Theo doi mot tuan sau khi tiem vacxin 8 Ipn khdng thay co bat ky
cac phan img bdt thudng nhu: met moi, chdn hoac bo an, tang than
nhiet va cac dau hieu benh Iy. Nhu vay, cho thdy vacxin AMERVAC
PRRS la an toan.
3.2 Ket qud theo doi sau khi cong c u ^ g d$c 3.2.1. Bieu hien
lam sang va thdn nhi^t sau khi cong cir&ng dpe
Lpn sau khi cong bang 2 loai virus PRRS vao ngay 32. Tir ngay 33
d6n ngay 46 theo doi nhiet d6 vd cac bieu hien Iam sang va cham
diem. K6t qud theo doi Iam sang dupe the hien trenbiludo lava lb.
Nhan xet ve lam sang: * Cong c u ^ g d$c v6i virus PRRS 21
- , c
2,0
1 1.5
J ''' Q
0.5
^ 1
/ X \ / ^^ *^ ^ *\ / ,y^^^ \ "\'"
J y* \ ^
- ^ V ) t 1 --DC-1
^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ .^ ^ .^
Bieu do la. Bieu hi^n tam sdng cua Iqn dirpv cong virus PRRS
21
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
- Sau khi nhilm virus PRRS 21, lpn 16 1 (VX-1) va 16 2 (DC-1)
bit ddu co nhimg bilu hien ddu tien sau 1-2 ngay. Trieu chirag
thudng thdy Id lpn giam nhanh nhen, an it hon miic binh thudng, lpn
ddi chung an it han lpn tiem vacxin.
- Trieu chung tien triln nhanh va nang han d nhung Ion ddi
chiing. Tir 4-8 ngay sau khi nhilm virus Id giai doan b?nh n$ng
nhat. cham chap, it van ddng va gidm dn. Mdt s6 cd trieu chung thd
nang nhpc hoac tim tdi d tai. Co 1 lpn (s6 11) d Id ddi chung cd
bieu hien benh nang han cac con cdn lai trong id, the trang rat met
mdi, thd ddc "kieu chd ngdi" vd co hien tupng
tim tai. Ddi vdi nhung lpn Id vacxin, cac tri?u chung tren khdng
bieu hien ro va thudng chi keo dai 1-2 ngdy, khdng lau nhu Ion ddi
chumg.
- Tir ngay 8-10 sau khi cdng (ngay thu 40 ttd di) cac trieu
chiing bSnh giam ddn, Ion nhanh nhen ban, an khde. Nhdm Ipn vacxin
den ngdy thu 42 da khdng con the hien trieu chiing. Nhom lpn ddi
chumg phuc hdi cham hon 3-4 ngdy. Rieng Ion sd 11 thudc 16 ddi
chumg bieu hien benh ngay mdt nang va chet vdo ngdy thii 44 (ngdy
12 sau cdng). * Cong cudng doc vdi virus PRRS VN07196
2.0
c
1 5
E 1 0 V
0 5
0 0
r^^~~~ / / /
/, /
/ \.., "\^
\ \ \ \^
V^ \ ^ \ , \
.^
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
Nhdn xet ve thdn nhiet:
-vx-2 -DC-2
-^ 4- -^ ^ -"' J ^ ^ ^ ; ^ ^ , ^ ^ ^ .^ .^ .^ .^ ^ ^ .
[3- I? ftp- li^ ^. ^ ^ ^ .^.
Bieu dd 2a. Diin bien than nhiet cua lan du^ giy nhi$m virus
PRRS 21
41.0
O 40.5
1 ' 40.0 c
S 39.5 1-
39.0
38 5
^ / r-^
r^--y~^~^^^^ It ^~~---4--;--,__--_^
J/> ^^ '^ ^
^^ -^^ /^ /^ 4> 4 ^^ ^^ ^^ ^^ >^ J> t^i^ >*^ >*
.^Q. .^ Qp . ^ ' . ^o . . ^ . ^ . ^ . ^ . ^o . ^ .^Qi .^ Q> ^ ^
Q i ^ Q ,
- . - V X - 1 - . - B C - 1
Bleu do 2b. Dien biin thSn nhi$t ciia /pn {fut>v giy nhiem
virus PRRS VN07196
Bieu do 2a vd 2b d tr8n th6 hi8n dien bien thdn nhi?t cua lpn
sau khi nhiem 2 loai virus PRRS.
- Than nhiet trung binh bat ddu tang hi ngdy thii 33 (virus PRRS
21) bic la sau khi cdng cudng dpe 1 ngdy.
- Lpn s6t cao nhdt vdo giai doan ngay thii 35-41 vdi than nhi$t
trung binh co liic len tdi
tren 41''C, ddc biet la cdc Ion d 2 Id ddi chumg. Tren bieu dd
cho thdy virus PRRS 21 gay sdt vdi thdi gian nhanh hon (sau 3 ngdy,
than nhiet trung binh tren 40C); tuy nhien virus VN07196 lai gay
sdt dai han (den ngay thii 44).
- Qud trinh sdt gidm ddn tir ngdy thii 41-42 vd lpn lai trd ve
miic than nhiet binh thudng. Rieng lpn sd 11 (Id 2) va lpn sd 8 (16
4) cd hien tupng giam than nhiet xudng dudi 38''C va chet.
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
3.2.2. Trang thdi virus huyit (Xem bdng 1)
Bang 1. Mipc do virus huyet tren Ion (tinh trung binh) L6
VX-1 BC-1 VX-2 DC-2
Ngay 29 40,00 40,00 40,00 40,00
Ngay 35 29,61 26,69 27,95 26,01
Ngay 39 27,15 24,29 26,93 24,32
Ngay 42 29,98 26,55 28,76 26,20
Ngiy 46 34,99 32,39 33,16 33,75
NgjiySS 37,72 37,23 36,63 33,65
(Ghi chit: Cl la ngudng vong cUa phdn img Realtime RT-PCR, ddnh
gia luong virus cao hay thdp, Cl cang thdp luang virus cdng nhieu
va nguac lai. Thong thudng phdn iing RRTPCR co Ct < 35 la duong
tinh Coi kit qud dm tinh virus huyet co gid tri Ct = 40)
Bieu do 3. Mux: do virus huyet
- Trudc khi cdng cudng doc (ngdy thir 29), khdng phdt hien thdy
virus PRRS trong huylt thanh tdt cd lpn d cac 16.
- C6ng cudng dpe d thdi dilm ngdy thii 32. Sau dd lay mdu vao
cdc ngdy thii 35, 39,42, 46 va 55 de kiem tra mire dp virus huylt.
Kit qud the hien tren bang va bieu do cho thay virus xudt hien
trong huyet thanh lpn dat cao nhdt vdo giai doan ngay thu 35-42
(tiic la ngay 3-10 sau khi
gdy nhilm) va giam dan d nhung ngay tiep theo. - Tai ciing thdi
dilm, lupng virus huyet cr
Ion thudc cdc Id ddi chiing cao han Ipn d cdc 16 vacxin tli 4-8
ldn (chenh lech 2-3 Ct).
- Den ngdy thii 55 khi ket thiic thi nghi?m, vdn cdn 1 lupng nhd
virus phat hien dupc trong huyet thanh Ign ddi chiing duac c6ng
virus VN07196. Cac nhom khdc khdng cdn virus trong huyet thanh.
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KHOA HOC KY THUAT THU Y TAP XXI S6 1 - 2014
3.2.3. Ddp umg miSn djch (Xem bdng 2 vd 3)
Bang 2. Ket qua kiem tra hieu gia khang the blng phu'tyng phap
ELISA
Lo
2
4
Virus CCD
PRRS 21
PRRS VN 07196
S6tai
2 4 5 13 9 10 11 12 1 3 18 19 8 14 15
Ngay 0 S/P
0,041943 0,335541 0,311258 0,280353 0,19426
0,328918 0,00662 0,015453 0,07064 0,00662 0,01987 0,011038
0,03532 0,04636 0,02649 0,00662
KQ Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg
Neg
Ngay 29 S/P
2,27807 0,0241 3,20321 3,59626 0,0214
0 0,03476 0,00802 2,63636 0,0187
2,29412 2,10695 0,03476 0,0053
0,04278
0,05348
KQ Pos Neg Pos Pos Neg Neg Neg Neg Pos Neg Pos Pos Neg Neg Neg
Neg
Ngay 55 S/P
2,3246 2,09607
2,538574 2,11936 1,41048
1,918486
KQ Pos Pos Pos Pos Pos Pos
LON C H T
1,606987 2,010189 1,416303 2,525473 1,570597
Pos Pos Pos Pos Pos
LON C H E T
1,770015 1,390102
1,528384
Pos Pos Pos
Bdng 3. Ket qua kiem tra hieu gia khang the bang phuxyng phap
IPMA
Lo
1
4
Vims cong
PRRS 21
PRI^S VN 07196
So tai 2 4 5 13 9 10 11 12 1 3 18 19 8 14 15 16
NgayO Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg Neg
Neg Neg
Ngay 29 640 Neg
1/2560 1/5120
Neg Neg Neg Neg
1/1280 Neg
>1/640 1/640 Neg Neg Neg Neg
Ngay 55 1/1280 1/640 1/1280 1/640 1/320 1/640
LON C H E T
1/640 1/640 1/320 1/1280 1/320
LgN CH^T 1/640 1/320 1/320
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
Nhdn xet: - Trudc khi tiem vacxin vdo ngay 0, tat cd 16
Ion ciia 4 Id deu dm tinh vai khang the khang virus PRRS (ca 2
phuang phdp xet nghiem ELISA va IPMA)
- Sau khi tiem vacxin Amervac cho 2 Id dupc 29 ngdy thay rang cd
6/8 con cd khang thi khdng virus PRRS. Ty le S/P trung binh vd hieu
gia khang the trung binh 16 1 cao hon 16 3. Khdng phdt hien dupc
khang the khang virus PRRS tren Ion cua 2 Id khdng tiem vacxin { am
tinh). Dieu nay chung td vacxin khong truyln ngang tir 16 thi
nghiem sang 16 doi chirng.
- Sau khi c6ng cudng doc 23 ngay (tire la
ngay thir 55) cd 4 16 deu cd khang the d 14 lpn sdng sdt (mdi 16
d6i chiing chet 1/4 lpn). Ty 1^ S/P trung binh vd hi$u gia khang
the trung binh d 2 Id tiem vacxin cao hon 2 Id ddi chiing Co the
nhdn thdy su chuyen biSn ddp iing miln dich tao khdng the thdng qua
cac ket qua ciia phuang phdp ELISA va IPMA sau khi tiem vacxin va
sau khi cdng cudng ddc.
Dilu nay chung to vi|c sir dung vacxin da kich thich hinh thdnh
dap ung miln dich ddc hiu. Ddp iing miln dich dupc thiic day va ham
lupng khdng the tdng cao 6 lpn dupc tiem vacxin nhd phdn iing hdi
lic sau khi lpn dupc cdng cudng doc.
3.2.4, Tdng trong (Xem bdng 4).
Bang 4. Theo doi trong lyvng trung binh cua \tyt\ 4 Id thi
nghiem
L6
Lo 1 (VX) Lo 2 (DC) L6 3 (VX) Lo 4 (DC)
Ttieo doi trijng lu'o'ng TB (Itg) NgayO
6,1 5,9 6,3 6,2
Ngay 32 (CCB) 14,4 14,3 14,5 14,6
Ngay 39 16,5 14,8 16,9 15,2
Ngay 46 19,2 16,1 19,8 16,6
Ngiy 55 22,8 19,0 23,5 19,6
- O giai doan sau khi tiem vacxin (ngay 0 den ngdy 32), miic do
tang trpng Ipm la tuong duong nhau giira cdc 16. Dieu nay cho thdy
vacxin kh6ng dnh hudng tdi qua trinh tang trpng d nhiing lpn dupc
tiem.
- Sau khi cdng cudng ddc (ngay thii 32 trd dl), miic dp tang
trpng giam hon so vdi tnrdc . Sau 23 ngay cdng virus PRRS 21, Id 1
tang 8,4 kg, 16 2 tang 4,7 kg, nhu vay 16 dung vacxin tang trpng
cao ban Id ddi chimg la 3,7 kg.
- Sau 23 ngdy cong virus PRRS VN 07196 16 3 tang 9 kg, cdn Id 4
tang 4,9 kg, nhu v?y 16 dung vacxin tang trpng cao hon 16 d6i chimg
la 4,1 kg.
L6 dung vacxin AMERVAC PRRS tSng trong tdt h
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KHOA HOC KY THUAT THU Y T A P XXI SO 1 - 2014
3.2.5. Bfnh tich dtfi the vd vi thi &ph6i
Virus PRRS 21
Virus VN07196
3ang 5. Cham di^m b^nh tich phoi khi
Ld 1 - vacxin So 2 3+
864 3+
So 5 I t
So 13 3*
Diem trung binii io = 2,50 Lo 3 - vacxin
S61 2+
So 3 2+
So 18 2+
So 19 1 +
Diem trung binii io = 1,75
mo Itham
Lo 2 - doi chijng So 9 3->
So 10 2+
s6ii 3+
S6l2 2+
Diem tnjng binh io = 2,50 Lo 4 - d6i clii>ng
S6 8 2+
S6 l4 1 +
S6l5 3+
S6l6 2+
Diem trung binh 16 = 2,00
Nhdn xet benh tich dai the:
Sau khi cong cudng doc, Ion ciia tdt cd cdc 16 thi nghiem va ddi
chiing deu cd cac benh tich d?i the viem d phdi. B6nh tich chu yeu
Id hien tupng viem ke, xuat huyet va khi thung, xay ra d tat ca cac
thiiy ph6i. Mpt sd Ion ddi
chung cd hien tupng teo thiiy phdi (nhdt Id thiiy tim). Cac hach
khi phe qudn bj viem, sung vd xudt huyet, xudt hien ca d Id vacxin
va Id ddi chiing. Benh tich dai th o phdi ciia Ign Id tiem vacxin
cd bieu hien viem nhg hon so v ^ Ign cua Id doi chirng.
Ld 2 - Doi chLPng cong PRRS 21
PhSl viem ke, xuit huyil Hach khi phe quan sung, xuit huySt
Lo 1 -Vacxin cong PRRS 21
1 Phdi xuk huyet nh? Hach mitig treo ruQt binh thucmg
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KHOA HOC KY THUAT THO Y TAP XXI SO 1 - 2014
L6 4 - Ooi chirng cong VN 07196
Phoi viem ke, xuat huyet Hach khi phe quan sung, phii
Lo 3 - Vacxin cong VN 07196
I"*
Qj Hach mang treo rudt binh thuung
Nhdn xet benh tich vi the: - Benh tich vi the cac 16 doi chiing:
Ld 2
(c6ng vims PRRS 21) vd Id 4 (cdng vims PRRS VN 07196) cd benh
tich nang phii ne mang phdi, vdch ngan gian rpng, Idng phe quan
chiia dich ri viem va tl bdo viem, hinh thanh huyet khdi, viem mach
tang sinh, vach phi nang day tang sinh te bao phi nang loai 2. Lo 2
cd bieu hien benh tich ndng ne hem 16 4.
- Benh tich vi the cdc 16 vx: L6 1 (cdng virus PRRS 21) va 16 3
(cdng virus PRRS - VN 07196)
cdu tnic phdi cac diiiy vdn cdn nguyen ven, mang phdi, vach ngan
ro rdng, vdch phe nang mong, cau tnic tiii khi rd rang.
Nhu vdy, khi cdng virus cudng doc PRRS, 16 dupc tiem phong
vacxin Amervac cd tac dung bao ve phdi va cac ca quan khdc nhu
lach, h?ch, amidan khdng bi virus tdn cdng, con Id khong tiem
phdng, phoi vd cdc ca quan ndi tang deu co biln ddi benh tich vi
thi ndng do su xdm nhap cua virus PRRS.
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KHOA HOC KY THUAT THU Y TAP XXI SO 1 - 2014
Mpt so hinh anh benh tich vi thg;
Lo 2 B/C (cdng virus PRRS 21)
: ~ ' - i 5 . ^ V
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KHOA HOC KT THUAT THI? Y TAP XXI S6 1 - 2014
L6 3 VX (cong virus PRRS -VN 07196)
Phoi: Binh thuxyng
IV. KET LUAN
Dua vao cac ket qua thuc nghiem neu tren, CO the riit ra cdc ket
luan nhu sau :
- Vacxin nhuac doc AMERVAC PRRS do hang Laboratorios HIPRA, S.A
san xuat dam bao an todn khi sir dung tiem phdng cho lan.
- Virus vacxin khdng truyen ngang tir 16 thi nghiem sang Id ddi
chimg va cd tdc dung kich thich sinh dap ung mien dich khi Ian bi
nhiem virus cudng ddc (hodc c6ng cudng doc) dap ung mien dich se
manh ban.
- Dap ling mien dich do vacxin tao ra cd tac dung 1dm giam miic
dp tram trpng cua benh thdng qua kiem tra benh tich dai the vd vi
the tren cac ca quan npi tang, dac biet la ph6i cua lpn sau khi bi
nhiem virus cudng doc PRRS.
- Lo diing vacxin AMERVAC PRRS tang trpng ban so vdi Id khdng
dimg vacxin khi cdng virus PRRS cuong ddc.
- Dap ling mien dich co dupc nhd vacxin da loai bd hoan todn
virus trong ca the Ipn vao khodng 2-3 tudn sau khi bi nhilm. Lpn
dugc tiem vacxin, khi bi nhiem virut cudng doc se khdng dao thai
virus cudng ddc ra mdi tnidng xung quanh.
TAI LIEU T H A M K H A O 1. Tian et al. 2007. PloS ONE 2: e526.
2. Li et al. 2007. Vet J. 174: 577-584.
3. Nam et al. 2009. Arch Viroi 154: 629-638. 4. Amonsinetal.
2009. f77-o/y. 16: 143. 5. RocaM. etal. 2012. Vet J. 193: 92-96
Nhan ngay 3.10.2013 Phdn bien 3.11.2013