KHAO SAT DAP L/NG KHANG THE SAU TIEM PHONG VACXIN D|CH TA HEO TREN HEO CON NHI§M
CIRCOVIRUS HEO TYP 2 ( PCV2 )
Nguyen Thi Thu Hong1, Le Thi Thu Phtfcmg1, Dang Hung1 Nguydn Ngoc Hai2, Chris. J. Morrissy3
TOM TAT
Khao sat dUdc tien hanh nhfim muc dich tim hieu tac dong ciia PCV2 trong dap Ung khang the' sau tiem phong vacxin dich ta heo. Tren 2 nhom heo thi nghiem: nhom 1 gom 10 bly heo dUdc tiem vacxin DTH luc 21 ngay va 51 ngay tudi dupe lay mau xet nghiem khang the khang PCV2 (phudng phap IPMA - immunoperoxidase monolayer assay) va khang the khang virut dich ta heo (phudng phap NPLA - neutralising peroxidase linking assay) luc 20, 50, 110 va 170 ngay tudi. Nhom 2 gdm 10 heo tach til 10 bay heo tU nhom heo 1. trUdc khi tiem vacxin DTH cho heo 0 trai luc 21 ngay tudi, dUdc chuyen ve khu chan nuoi each ly d Navetco.
Ket qua ghi nhan diln bien dap Ung khang the khang virut DTH sau tiem vacxin DTH ciia cac nhom heo bi nhilm PCV2 (nhom 1) hay khong nhiem PCV2 (nhom 2) deu tUdng tu nhau.
Khao sat cho thay tinh trang nhiem PCV2 khong anh hudng den dap Ung khang the sau tiem phdng vacxin DTH.
Tii: khoa: Heo con. Dich ta heo, Tiem phong, Dap Ung khang the' Antibody's response to hog cholera vaccination
in piglets with Porcine Circovirus type 2 (PCV2) infection Nguyin Thi Thu Hong, Le Thi Thu Phirong, Bang Hung,
Nguyen Ngoc Hai, Chris. J. Morrissy SUMMARY
The study was realized for the aim to determine the effect of PCV2 infection on antibody's response to hog cholera vaccination. Two groups of pigs were arranged in the experiment, the first group consiste 10 litters from which the pigs were taken serum at 20, 50, 110 and 170 days old and vaccinated with hog cholera vaccine at 21 and 51 days old;
and the second group consiste 10 pigs that were chosen from the pigs of the second group before making hog cholera vaccination and were transfered to the experimental station of Navetco company.
' Cong ty thuoc thu y TW, Tp. Ho Chi Minh 2Dai hoc nong linn. Tp. Ho Chi Minh
'Australian Animal Health Laboratory. CS1RO. Geplong, Australia
The results of study showed the similarity of antibody titers anti hog cholera virus in the pigs with (groupl) and without PCV2 infection (group 2).
The study demonstrated that the PCV2 infection could not effect on the antibody's response to hog cholera vaccination.
Key words: Piglet, Hog cholera, Vaccination, Antibody response I. DAT VAN DE
Benh djch ta heo (DTH) la benh truyen nhiem gay thiet hai trim trong ve mat kinh te cho nen chan nuoi heo. Phong benh bang vacxin DTH la mpt trong nhUng bien phap quan trpng dUdc =U dung pho bien hien nay.
Tuy nhien, hieu qua tiem phong vacxin DTH phu thupc vao nhieu yeu to': trong dd co yeu to' cpng nhiem vdi cac tac nhan gay benh khac (Suradhat va cs, 2007). Chang han nhu virut PRRS gay Uc che dap Ung mien dich chu dpng do tiem vacxin DTH (Li va Yang, 2003). O nUdc ta, Porcine circovirus typ 2 (PCV2) duoc phat hien d mpt s6' tinh thanh tU nam 2000 vdi ty le nhidm 38,97 % nhung den 2006 ty le nhiem da tang den 96,47%, chUng to PCV2 dang luu hanh phd bien trong chan nudi heo (Nguyen Thi Thu Hong va cs, 2006) va la mpt trong nhung nguyen nhan gay coi cpc heo sau cai sUa d mot so' trai heo tai thanh phd' Ho Chi Minh (Lam Thi Thu Huong va Duong Chi Mai.
2006). PCV2 gay Uc che mien dich tren heo benh (Chianini, 2003; Nielsen va cs, 2003), do do cd the anh hudng den hieu qua mien dich cua cac vacxin dUdc tiem trong khoang lUa tudi heo cd the nhiem PCV2. Tuy nhien, cho den nay chua co bao cao ro rang ve anh hudng ciia PCV2 ddi vdi dap Ung mien dich do tiem vacxin DTH tren heo.
Trong nghien cUu nay. chung toi se khao sat dap Ung khang the do tiem vacxin DTH tren dan heo co nhilm va khong nhiem PCV2 nham danh gia anh hudng ciia PCV2 ddi vdi dap ling mien djch do tiem vacxin DTH tren heo.
II. NOI DUNG VA PHUGNG PHAP NGHIEN CUU
1. Vat lieu thi nghiem
Vacxin DTH chung C dong kho san xuat tren be do Navetco san xuat. Lieu sii dung theo qui dinh ghi tren nhan.
2. Bo tri thi nghiem
Trong khao sat nay, chan doan phat hien PCV2 tren dan heo thi nghiem DTH khong duoc thuc hien. Thi nghiem dUdc tien hanh tren 2 nhom heo: nhom 1 gdm 10 bay heo dUdc lay mau xet nghiem khang the khang PCV2 (tai thdi diem nay chua cd vacxin phdng PCV2) luc 20. 50, 110 va 170 ngay tudi. Nhom 2 gom 10 heo lay tU 10 bay cua nhom 2 trudc khi tiem vacxin DTH cho heo d trai luc 21 ngay tuoi. chuyen ve khu chan nudi each ly d Navetco.
Nhdm 1: heo dude tiem vacxin DTH luc 21 ngay va 51 ngay tudi.
Nhom 2: Tiem vacxin DTH cho 8 heo, 2 heo khong tiem vacxin DTH (doi chUng) va xet nghiem khang the khang DTH va PCV2 cung cac thdi diem vdi 10 bay heo 6 nhdm 1.
3. Phifcmg phap danh gia
- Phudng phap NPLA (neutralising peroxidase lmkmg assay) phat hien khang the khang virut DTH. Hieu gia khang the 3 log2 dUdc xem la co khang the khang virut DTH.
• Phudng phap IPMA (immunoperoxidase monolayer assay; phat hien khang the khang PCV2. Hieu gia khang the tU 5,32 log2 dUdc xem la co khang the khang PCV2.
- So sanh diln bien hieu gia khang the (HGKT) khang DTH tren dan heo a cac nhom.
m. KET QUA VA THAO LUAN
1. Xac dinh heo nhilm PCV2 thcfc dia thong qua khang the hinh thanh tii 50 ngay tuoi
Do dieu kien chan nuoi ciia trai khong cho lay mau heo con ngay sau khi sinh, nen chung toi da lay mau heo me ngay sau khi de va lay mau heo con bat dau tU 20 ngay tuoi.
Nai 1 2 3 4 5 6 7 8 9 10
NhU vay HGKT trung binh khang PCV2 tren heo con cao d 20 ngay tudi. giam dan va am tinh chiem 50% tdng dan (gdm cac bay heo ciia nai 4, 5, 7, 8 va nai 10) vao luc
Diln bien trung binh HGKT khang PCV2 tren 10 bay heo qua cac thdi diem 20, 50, 110 va 170 ngay tuoi dUdc trinh bay qua bang 1, cho thay co su giam HGKT khang PCV2 theo khuynh hudng hieu gia cao tai thdi diem 20 ngay tuoi va giam thap tai thdi diem 50 ngay tudi. Khuynh hudng giam HGKT cho den 50 ngay tuoi d dan heo nay phu hdp vdi chieu hudng giam ciia khang the thu dpng (KTTD) khang PCV2 vdi thdi gian ban huy la khoang 19 ngay (Gillespie vii cs. 2009) vii muc dp giam ciia cac KTTD khang PCV2 khac nhau tren heo (Opriessnig va cs, 2004).
12,64 170 1,15 13,52
0,35 12,48
1,83 13,44
0,42 13,64
0,00 13,02
0,92 13,64
0,00 14,79
0,90 14,14
1,91 14,48
2,40 50 ngay tudi (hieu gia khang the duoc xac dinh la dUdng tinh vdi PCV2 khi gia tri nay Idn hdn 5,32 log2), sau dd hieu gia khang the da tang rat nhanh tren tat ca 10 bay, Bang 1. Dien bien khang the khdng PCV2 tren dan heo nhdm 1
So heo
(con) Thong ke
Trung binh hieu gia khang the IPMA theo ngay tudi (log2)
20 50 110
X
SD 12,39
0,46 7,32
0,00 8.61
2,43
10 X
SD 9,98
0,52 6,66
0,82 10,32 0,00
10 X
SD 9,61
5,49 6,28
2.56 8,28
3,65
10 X
SD 2,66
4,00 2,53
3,37 10,32 0,00
10 X
SD 9,50
0,38
4,93
2,47 10,32 0,00
10 X
SD 10,14
0,85 6,99
1,45 11,02 1.47
10 X
SD 5,02
1,91 2,61
2,47 11,44 1,10 X
SD 8,89
0,89 4,37
2,73 10,32 0,00 X
SD 11,44
0,84 7,12
0,45 7,86
4,48 SD X 8,44
0,84 5,03
2,16 10,04 0,76
the hien d hieu gia khang the luc 110 ngay tudi (Bang 1).
Trong dieu kien thUc dia, hiu het cac dan heo gidng deu nhiem PCV2 dan den dan heo con sd tinh deu co KTTD khang PCV2 vdi hieu gia khang the khac nhau trong huyet thanh (Opriessnig va cs, 2004). Vao nam 2006, d trai heo chung toi tien hanh thi nghiem nay cd ty le heo nai nhilm PCV2 la 100 % va trai nay chua tiem vacxin phdng PCV2 cho heo. TU do.
chung tdi nhan thay cd md'i tUdng quan kha chat giUa HGKT khang PCV2 tren heo me (lay mau heo me ngay sau khi sinh heo con) va HGKT khang PCV2 tren tren nai va tren heo con luc 20 ngay tudi (sd lieu khdng trinh bay).
Dieu quan trpng hdn ca la dap ting khang the khang PCV2 tren heo mln cam (khdng cd khang the khang PCY2i dUdc gay nhiem vdi PCV2 chi bat dau hinh thanh it nhat vao ngay thU 14 sau khi gay benh (Meerts va cs. 2006:
Nguyen Thi Thu Hong va cs, 2008).
Ddi vdi 10 heo dUdc chuyen ve nuoi each ly d khu thi nghiem ciia Navetco luc 20 ngay tudi, bang phUdng phap PCR da khdng phat hien cd virut PCV2 trong huyet thanh cua ta't ca 10 heo, nhung tat ca deu cd HGKT khang PCV2. Khang the nay hau nhu giam dan den ngUdng am tinh vao thdi diem 50 ngay tuoi trd di va hoan toan khong phat hien cd khang the vao luc 110 ngay tudi. Ket qua nay cho tha'y 10 heo nudi d khu thi nghiem nay khong bi nhilm PCV2 tu nhien (Bang 2).
Bang 2. Dien bien khdng the khdng PCV2 tren heo nuoi a khu thi nghiem So tai heo Hieu gia khang the khang PCV2 theo ngay (log2)
So tai heo 20 50 80 110
3217 7,64 5,32 - -
3221 7,64 5,32 - -
3242 7,64 6,64 - -
3244 5,32 4,32 - -
3245 5,32 5,32 - -
1615 6,64 5,32 - -
1634 9,64 7,64 5,32 -
1635 8.64 6,64 - -
Trung binh 7,31 + 1,51 5,82 ± 1,06 - -
1616 7,64 - - -
1620 6,64 - - -
l tinh
Nhu vay, dua vao dien bien HGKT ciia dan heo thuc dia (Bang 1, Bang 2) co the nhan dinh ring khang the khang PCV2 tren heo luc 20 ngay tudi d heo la KTTD. HGKT nay d diem thap nhat vao khoang 50 ngay tudi. Gillespie va cs (2009) cho ring hieu gia KTTD du cao nhung khong hoan toan bao sre heo chdng lai viec nhiem PCV2, cdn hieu gia
KTTD thap thi chic chin heo se bi nhilm PCV2. Ngoai ra. KTTD khang PCV2 tit me truyen giam gan nhu am tinh hoan toan nen heo con trd nen nhay cam vdi PCV2, do vay PMWS tac dong chu yeu tren heo tii 7 tuln tudi (Harding va cs, 1997), va ngay ca tren heo con theo me (Giau-Roma va cs, 2009). Theo Meerts va cs (2006), dap Ung
khang the* khang PCV2 chi hinh thanh tren heo sau khi bi nhilm PCV2 it nhat tii 14 den 28 ngay. Nha vay, heo trong khao sat nay co the nhiem PCV2 vao giai doan truoc 50 ngay tudi, dan den ham ludng khang the tren dan heo mdi co the bat dau tang tii thdi diem sau 50 ngay tudi va dat hieu gia cao luc 110 ngay tuoi; nhat la cac bay am tinh khang the khang PCV2 luc 50 ngay tuoi nhu bay ciia nai 4. 5, 7, 8 va nai 10 tUdng Ung vdi hieu gia 10,321og2, 10,321og2, 11.44log2, 10,321og2 va 10,04log2 (Bang 1).
PCV2 lam hu hai nhUng te bao mien dich va lam suy yeu he thdng mien dich cua heo.
Opnessnig va cs (2006) chiing minh PCV2 cd gay tac dong bat Idi den dap Ung mien dich do tiem vacxin PRRS. Rieng anh hudng PCV2 den dap Ung mien djch do tiem vacxin DTH nhu the nao v5n chua dUdc xac dinh ro.
2. Danh gia anh hitting nhiem PCV2 den dap ling khang the sau tiem vacxin DTH PCV2 lam hu hai nhUng te bao mien dich, anh hudng den dap Ung mien dich doi vdi cac vacxin tiem phong cho heo xoay quanh khoang thdi gian nay. Tuy dan heo nhdm 1 gdm 10 bay d trai bi nhiem PCV2.
dan heo nay van cd sU gia tang dan hieu gia khang the khang virut DTH sau khi dupe tiem vacxin liic 21 ngiiy va 51 ngay tuoi.
Dieu thu vi la tat ca 10 heo nudi each ly d Navetco deu khong phat hien co khang the khang PCV2 tU thdi diem 50 ngay tudi trd len, cho thay cac heo nay khdng bi nhiem PCV2 tu nhien. Dien bien dap Ung khang the khang virut DTH tUdng tu nhau giUa 2 nhdm heo nhiem va khdng nhiem PCV2 thUc dia (bieu dd 1).
HGKT(log21 12.0 T
Bieu do 1: Die'n bien khdng the khdng DTH vd PCV2 tren heo trai va heo thi nghiem
Dieu nay cho thay PCV2 hinh nhu khdng anh hudng den dap Ung mien dich do tiem vacxin DTH tren heo trong khao sat ciia chiing toi. Cung thdi gian nay, nghien cuu ciia tac gia Chiou va cs (2006) da chung minh rang PCV2 khdng anh hudng den dap ung mien dich dich the va mien dich te bao tren heo sau khi tiem vacxin DTH va vacxin gia dat. Dieu nay dupe lam ro them khi
PCV2 khong gay anh hudng ro rang doi vdi hinh thanh dap Ung mien dich djch the khi gay nhiem ddng thdi PCV2 va PPV (Esther va cs, 2009). Dieu hien nhien la hien tUdng giam te bao lympho chi xay ra tren nhUng heo nhiem PCV2 cd gay bieu hien lam sang ciia PMWS, nhUng khdng ed a heo nhidrn PCV2 nhung khong phat benh nay (Nielsen va cs, 2003).
PCV2 gay nhiem hau het cac dan heo, nhat la trai chung toi thi nghiem, heo nai nhilm PCV2 v6i ty le nhilm tang td 80,64%
nam 2004 den 100% vao nam 2006 la thdi gian chung toi thuc hien khao sat nay (Nguyln Thi Thu Hong va cs, 2006; 2008).
Neu PCV2 co anh hudng den dap Ung miin dich tren heo sau tiem phong vacxin DTH thi at han benh DTH se bung phat nhieu hdn nhung thUc te cho thay vacxin DTH da co hieu qua trong phong chong benh DTH tai trai heo khao sat.
IV. KET LUAN VA DE NGHI
Trong cac khao sat cua chung toi, qua so sanh hieu gia khang the khang virut DTH va khang PCV2, khong nhan thay anh hudng cua PCV2 den hieu qua mien dich sau tiem phong vacxin DTH. Dieu nay rat cd y nghia la loai dUdc nguyen nhan nghi ngd cd anh hudng den hieu qua mien dich sau tiem phdng vacxin DTH tren dan heo co sU hien dien ctia PCV2. Tuy nhien, can nghien cUu anh hudng ctia PCV2 khi ket hdp vdi cac tac nhan gay benh khac (PVCAD, PRRS) den hieu qua miin dich cua vacxin DTH.
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