- Th^nh phan hoa hgc va tmh khong thuan nhat: Chi kich thuoc vd tinh la chua du dl xac dinh
1.4.33.Hinh thdi va ciu true
ị4.ịyirut sm
1.4.33.Hinh thdi va ciu true
Hinh thdi Nhiing vimt hodn chinh cd dudng kinh khodng 75nm, gidng hdt nhu mdt cdi
bdnh xe cd cdc gai ngdn vd mgt cdi vanh rat nhdn. Ten vimt Rota tir tilng La tinh Rota co nghia Id bdnh xe bit diu bdi hinh thdi ciia nọ
cdu triic
Dudi kinh hien vi dien tu, vimt Rota cd dang khoi cau 20 mat, dudng kinh khodng 75nm, Chuoi nucleocapsit ciia vimt dugc tao thdnh bdi 3 vdng xoan đng tam gom 11 doan ARN kep . Capsit ciia vimt Rota cd dang đi ximg 20 mat, 132 capsomer sap xep doi xiing xoan
c i u tnic capsit ciia virut Rota gdm 3 ldp- - Ldp ngodi chira protein ciu tnic VP4 vd VP7 .
- Ldp trong chiia protein cau tnic VP6 la loai khdng nguyen dac hieu nhdm, chilm 50% hat vimt vd cd the dugc phdt hien trong ky thudt ELISẠ
- Ldp Idi chira protein ciu tnic VPl, VP2 vd VP3.
Cdc nghien ciiu bdng ky thuat dien di mien dich vd kinh hiln vi dien tu da khdng dinh: Cdpsit trong mang khdng nguyen đc hieu nhdm, capsit ngodi mang khang nguyen dac hieu typ, nhdn cda vimt khdng mang tinh khdng nguyen.
Chu thich: - Neutralization antigen: Khdng nguyen trung hod
- Subgroup antigen: Khdng nguyen phdn niidm - Core: Loi
1.4J.4. Cac thanh phan hoa h9C cua virut Rota va chu-c nang
Axit nucleic
Li ARN soi kep g6m 11 gen, co do Ion khoang 18 nghin cap bazo, trong lugng phan tii ttr 11.10 - 14.10' dalton. M6i gen co trong luong phan tit tit 2.10' - 2,2. 10 " dalton vi ma hoa cho mpt protein cau tnic hoac khong ciu tnic.
Protein
Hat virut chiia it nhit 6 protein ciu tnic: Cic gen 1, 2, 3 vi 6 ma hoi cho cic protem VPl, VP2, VP3 vi VP6 [45, 56]. Doan gen 4, 9 ma hoi cho cic protein capsit lop ngoai VP4 vi VP7 [57]. Cic gen c6n lai (5, 7, 8, 10 vi U) mi hoi cho cic protein khong ciu tnic (NSPl, NSP2, NSP3,NSP4,NSP5).
Ba protem mang tmh die hieu khang nguyen ciia vuut li VP4, VP6 vi VP7 [9, 39, 58]. VP7 li mpt glycoprotein (G serotype) la khing nguyen tnmg hoa die hỉu cho typ huySt thanh. VP4 li mpt protem nhay cim voi proteaza (P serotype) li khing nguyen co die tinh ngung kSt h6ng ciụ Nho enzym phin hiiy protein, VP4 dupe tich ra mpt cich dac hieu giiip cho sir xim nhap ciia virut
vio te biọ VP6 li khing nguyen chung cho cic duoi nhom cua virut Rotạ Trpng lupng phin tix,
vi tri, chiic ning cac protem ciia virut Rota dupe trinh bay o bing 2. Bing 1.4. Die diim protein ciia virut Rota
Dôn gen 1 2 3 4 5 6 7 8 9 10
Sin phim Protein
VPl VP2 VP3 VP4 NSPl VP6 NSP3 NSP2 VP7 NSP4
Trgng Iirgng phan tir (M)'
125.005 (125K) 102.431 (94K) 102.431 (94K) 98.120 (88K) 86.782 (88K) 58.654 (53K) 44.816 (41K) 34.600 (34K) 36.700 (35K) 37.368 (38K) 20.290 (28K)
Vi tri trong hat virut
Loi capsit Loi capsit Loi capsit Capsit lop ngoii Khong cau tnic capsit Icrp trong Khong cau tnic Khong cau tnic Capsit lop ngoai Khong cau tnic
Doan gen
11
San pham Protein
NSP5
Trgng lulling phan tir (M)*
21.725 (26K) (adsbygoogle = window.adsbygoogle || []).push({});
Vi tri trong hat virut
Khong ciu tnic Ghi chii: (M)" la trpng lupng phin tii cua protein chiing SAl 1
1.4J.5. Phan nhom v i typ huyet thanh
Phan nhdm
Theo Lambert J.P (1992) vuut Rota dupe chia thanh 5 nhom A, B, C, D vi Ẹ Nhom A co 2 phin nhom Ii 1 va 2, phan nhom 1 co typ huyet thanh 2, phin nhom 2 co typ huyet thanh 1, 3 vi 4 .
Baoming (1995) chia virut Rota thanh 7 nhom A, B, C, D, E, F va G, trong do chi co nhom
A, B, C gay benh cho ca nguoi vi dong vat. Nhdm D, E, F, G chi thiy a dSng vat [3, 63]. Nhom A hay gip nhat, gay ra hiu bet cic v^ djch tieu chiy ning o tre em. Nhom B, C thucmg giy nhiing vu
djch le te, hay gip 6 tre 16n vi ngu&i trucrag thanh .
Tfp huyit thanh
Trong m5i nhdm, virut Rota dupe phan loai theo cic typ huySt thanh, VP4 li mpt loai protein ch6ng phin tich proteaza - protein P vi VP7 mpt Ipai glyccprotein - protem G. Hai protein niy li 2 protein ciu tnic lop ngoai cimg quyet dinh typ huyet thanh ciia virut va dupe coi nhu mpt nhin t6 hing diu trpng nghien ciiu sin xuit vicxin vi chiing dong vai tro quan trpng trong qui trinh hung hoi khing huySt thanh. Hai thinh phin gen ma hoi cho nhung protein niy theo ly thuySt co
thk phan chia dOc lip vai nhaụ 14 typ VP7 da dupe phat hi$n bing phin ling trung hoi giim dim
hosd tir, 10 hong 14 t ^ tren xuit hi$n o nguW va da dupe xic dinh boi phin iing trung hoi cheo
v6i cac mau huySt thanh dpng vit da gi6ng. Cic typ huyet thanh niy tuong quan v(5i cic die diem khang nguyen cia glycoprotein VP7. Hien nay, chiing ta van chua sin xuit dupe khang huyet thanh da giong vi don gi6ng khang die hieu khing nguyen VP4, vi vay da cin tro su phan loai cic typ huyet thanh VP4. Tuy nhien, dya vio phan tich gen nguoi ta da phit hien ra it nhit 19 typ huyet
thanh VP4 [41] . Vi mit ly thuyjt se co rat nhiSu chung virut Rota cua nguoi khic nhau boi su kit
hpp cua cic typ huylt thanh G vi P. Nhung that may min hen the gioi chi co 4 chiing vmit Rota chii yeu phin b4 G1P8, G3P8, G4P8, G2P4 (hinh 4). Diy la mot thuan ipi cho muc dich phit triln vScxm [66]. Tuy nhien, sv luu hanh ciia cic chiing vuut Rota co khic nhau ding ke o cic vimg khi
hju khic nhau, mpt s6 chiing khong thong thucmg lai phan b6 a mpt vai qu6c gia dang phit tnia,
ching h?n P6 ket hpp vcri typ huylt thanh G9 chilm 9,5% t6ng s6 cic chiing vuut Rota o in Dp.
1.4J.6.Ttnh chit hoi 1^
Siic de khdng vdi nhi^t dp
Trong phdn, d nhidt dg thudng virut tdn tai nhieu ngdỵ d 4'*C tham chi d 20°C vdi sy cd mdt cua 1,5 mM CaCh vimt Rota van giu" dugc tinh gdy nhiem triing trong niiilu thang [ 57]. d - 20 C vimt cd the tdn tai nhilu nam. Vimt de bi bit boat d nhiet do cao hen 45'^C. Nlu đng tan bdng nhidu lan thi vimt mit khd nang gdy nhiem trimg [57]. Vimt cd kha ndng tdn tai Idu trong buong benh nhdn ndn ty If nhiem trimg bfnh vien khd caọ
Tinh ben vimg v&ipH
Vhut Rota ben viing vdi pH d difn rdng tii pH: 3 den pH: 10, nhd do ma vimt Rota cd thi tdn tai vd phat trien tdt trong mgt ngudị
Cdc tinh chat khde
• Tmh nhay cdm:Khd nang gdy nhiem trimg ciia vimt Rota tiiy thudc vdo sy cd mat cua ldp
vd capsit Vimt Rota nhay cdm vdi EDTA (etiiylendiamintetra acetic), EDTA cd khd ndng phd vd ldp vd capsit vd 1dm mit khd ndng nhilm trimg ciia vimt [23,32]. Sodium thyocianate biln hat vimt cd 2 ldp thdnh h§it vuoit chi cd 1 ldp capsit. Sodium dodecyl sulfate 0,1%., phenol, formalin, betapropiolacton vd đc biet Id ethanol 95% Id chat khii trimg hifu qud nhit lam mit ldp vd capsit cua vimt.
- Tinh de khdng: Vimt Rota ndi chimg de khdng vdi fluorocacbon, ete, chloroform, deoxycholate vd dung dich khdng ion. Vhut Rota ciing khdng chiu tdc dyng cua khdng sinh, chi dimg khdng sinh trong trudng hgp bdi nhilm hay nhilm khuin phdi hgp .
1.4.3.7. Nudi cay
Tinh thich nghi cua vimt Rota vdi nudi cdy tl bdo cdn khd khdn. Cd thi nudi ciy vimt tren te bdo th|in bdo thai ngudi, te bdo niem mg.c mdt bdo thai ngudi vd tren mgt sd gidng te bdo thudng tryc cd nguon g6c tir tl bdo thdn bo, td bdo than Ign vd te bdo thdn khi xaiih Chau Phị.. Ngodi ra, chiing Rhesus Rotavimt (RRV), SAU d khi, CVl d chd vd chiing TYl d lira cd the phat triln cd hifu qud tren tl bdo Hep2, mgt gidng te bdo thudng tryc lay tir u nguyen bdo gan thai ngudị Phin Idn chiing vimt Rota ngudi khd mgc trdn cdc te bdo nay, hon niia cdc chiing vimt Rota cua ngudi dudng nhu dl mit Idp vd capsit hem cdc chimg khde, tuy nhien hau het cdc chung ciia cd ngudi vd đng v§t l^i phdt trien hifu qud tren td bdo MAI 04 (lay tir tl bdo than khi) vd te bdo CaC02 (Idy tir tl bdo ung thu bilu md dai trang ngudi). Phuong phdp hifu qud dl nudi ciy vimt Id ciy tren te bao th§n khi Cynomolgus cd sii dyng cdc enzym phdn gidi protein: trypsin, pancreatin. Sau nhieu lan cdy tmyen, hifu gid vimt se gidm dị