Chukwuedo, AA

Gowalk, NE

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 Chub1ucdo and Gomwalk (2005) N1g J B1otcch 16 (I) 112 · 120 112 GROWTH COMPARISON OF NIGERIAN STRAINS OF FOOT AND MOUTH DISEASE VIRUS (FMD V) TYPES SAT 1 AND SAT 2 IN BHK, BK, VE RO AND LK CELL CULTURE SYSTEMS 1C lll ll<\VUEDO, AA *. AN D 2c;o ! W A Li\'. , .E. I. ational Veterina ry Research. Institute. f-M D Laborat ory P. 0. box 207 Vom Plateau Stale Nigeria. 2. Department o f Medical microbiology. faculty o f Medica l Science University of Jos . .los Plateau State Nigeria Corresponding Author*. ABSTRACT The growth characteristics of different strains of 1wo Ster.cot~ pes of foot and mouth disease 'ints (FMDV). SAT I and SAT 2. were compared in four cell culture sys1c1m (BllK. \ cro. BK and LK cells) S,\ T I Strains yielded the highest virus ti tres (6.85 log10 TCID 50/ml) in BK cells follo\\ed ti: BHK eel' (5 6lo; TUD,. ml) wh ile the lowest titres v.ere obtained in LK cells (3 5 log10 TC ID,o ml l lhe <;\- ~ '1rat:is ~relded lc-•.1er 11r11s tilres in BK lells system compared to the S/\ T I. The SAT 2 had ils h1l!hcst lilrl .'1 BK :: I (6::' lo;: -cm ... 1111) fol lo11 ed by vero cells (5.851og111 TC IDs<> mil hul lowest 111 I K cell (3 Xlogio lCID!O'ml) All lh ' ru' 'lr.1111' grew tn all the C<'ll culture systems but their gro11th vary from one cell in another and abo from ~:ram to '11a111 "ilhtn the \rn1t1pc' The virus - cell adaptation and sens111vit) or s11sccp11bilil~ 1111pro\c<; 1111'1 r~ tcd pao;'a!'-'' of v1ru~ 111 1hc ct•ll monolayers. Although BllK 21 cell arc rccom111c11dcd IN I \ ID\ ilSS<I) r e!>t' eels cu11i;rcs 1hat suppnrtt·d lhc virus gro"th may scr1c a~ <1 1icrnat1vc 111lh f11nhe1 11111•,11ba1 <'ll' hence concluctccl 111th more cell cullurc '~ ~1t·111' Ke) words Foot and 1110111h d1~ca~c. cell culture. '\i\'I 1. S \ I 2 INTRODUCTION Foot and Mouth Disease Virus (Fi\ 11)\') 1' chc cau1;c or f\1nt <md mouth disease. a h1ghl~ contagious 111fcctious disease of clmcn h1H1rcd dome-,11c ll\c't'1~i.. . 11dd and animab of agricultural importance (Sherry er al 2000; \hcg1111de er al 20ll:\. ~i.1111~c1n I 'l'>4 . the disease 1s characterized by vesicuJar lesions and subs1:quc111I~ b~ cr,1,ion or the cp1thcliu111 of the mouth (Ferris Danaldson 1992). fhe disease hmvc1·cr is assuming increasing!) importance in Nigeria because of the present government e ffo rts to upgrade and improve 1hc indigenous cattle with the exotic breeds for increased meat and milk productions (Chukwuedo cl al; 2003). Since 193 1 virus types 0. A. SAT I and SAT 2 have been isolated in series of outbreaks (Abcgundc er al, 1988; Ezeokoli el al. 1988). In most countries of the world, the disease is controlled by s laughter and immunization with chemically inactivated who le virus vaccine (Eric  <.. h11i...\\lll'J1 .111d (,, 111\\.J IJ.. t~\11 I '•g I H1\11t:d1 1(1 I ..:10/. 1998). !"his present stud) tkscrihl'd th1.· ~l"ll\\lh 111 '-i);!l'rl.I I \ti)' 1111' and S:\ I 2 in different cell systems. i\ IATERI A L S AND i\IETllO DS Viruses: 1\ total or 14 F~~[) ,·1rus isolates \\l'l"L' used. I hesc include :\ig I 9..J Nig 5/97 I ig 5/95 I'\ 1g ::: <)..j Nig 1/1)8 Nig 2/97 >Jig 3 9..J ig 2/2000 ' ig 4/97 '-!1g (i 95 Nig 1195 Nig 3/98. Sta ndard Antigens And Antibodies '.:1g.l /<)(1 Nig J/95 11; ·rnt~ p1.·-., '-i .\ I I r!1e standard ant igens and antibodies used includes: virus infections antigen (VIA), 1465 antigen to S/\TI and S/\T2. Antibodies to VIA and 146s antigens, speci fi c type antibodies to SAT! and S/\ T2. All the reagents were obtained from Animal Virus Research Institute (AVRI). Pirbright. l ' .K. Phosph ate Buffe red Sa line (Pbs) The PBS consists of 8.0g NaCl, 0.2g 1.,: H2P04, 2.9g Na2P04. l 2H20 , 0.2g KCL. The salts were dissolved in one litre of dist illed water and the Pl I was adjusted to 7.4 with NaOH or HCL. The Saline was sterili zed by autoclaving at 121°C and IOlbs pressure for 10 minutes, allowed to cool and store at -l"C ready for use. Compl ement (Ci) crum from male guinea pigs taken after 24 hours starvation was used as a source of complement. The guinea pigs were bled th rough cardiac puncture and the blood was allowed to clot. store at +4°C overnight and centrifugcd· at 2500 rpm fo r IS minutes in cold (M.S.E England) centrifuge. The supernatant was carefully aspirated into steril e bijou bottles in aliquots and store at -70°C Revco. Verona! Buffe red Diluent (Vbd) Verona! buffered saline was fresh!) prepared from oxiod tablets (0\ oid Ltd. UK). Sheep Red Blood Cell i. The sheep red blood cell 'vvas collected from N.V.R.I sheep through the j ugu lar veins in Alservers solution. washed three time in \1131) and packed at 2000 rpm for 5 mtnu1.:s using a bench centrifuge (M E Super Minor England) An approximately 4% cell suspension was prepared. Haemolytic Cel l In dicat or 'ys tcm Lyophylized Rabbi t anti-sheep reel blond cell-. . erum (hacm<,lys111) was obtained from Burroughs Welcome, U.K. The haemolysin \\'as reconstituted and titrated 1n a chequered board format against complement. Aliquots of 4% SR,f3C suspension \\'as mixed \\'ith equal vol umes or varying (2 fold) dilutions ofhaemolysin. Sensitization \\'as fo r 30 minutes at room temperature. Complement dilutions were prepared 111 a t\\ O fo ld series from 1110 and he ld at +4°C until used 25ml each of the \ariOUS dilutions of the antigen and the antibod ~ \\'CrC added to the corr~sponding \\ells of the micro titre plate. I his "as incubated at] 7"C for 15 minutes lollcrncd b) 25 ul of the complement di lution and 111rnba tion at :; 7''C i"nr I hour . I he 25 ul of srnsiti1.cd  Chuk" ucdo and Go1m1 al~ (2005) N1g J l3101cch 16 (I) 112 · 120 I I ·I SRBC suspension was fina lly added and the n:agcnts incubated at 3 7''(' for I hour artcr which the result was read. (Da\ ic: 1964) Counter lmmun o 1-:il'ct ro phorcs is (Cir) Tt•1,t ·1 \\00 rtl\\S of paired wells \\ere drilkd l\11 <l gl11-..s slide lll,tkd \\ llh .iµ.irn-.c )!l'I I he n~· hl column 11clls contained the anti hod~ "h1k k i'l cPlu11111 "cll" Llllll.111Kd lhc .111!1):'.l'll I hl· 11 cll -. were 8111m 111 diameter lhc distance hct11ce11 the lll ll .11111gc11 ,111d !ll P .11111hnd~ 11dl' 11erc 4111 111 1\hilc the distance between the antigc11 and <1nl1hod~ wells l\Cre 2111111 I he (\\() 1"(1\\'> or palrl'll wells \vere I cm apart and the wick is I cm a11.1~ rrnm the acl,iaccnl 11cll-. rhe test slide \\aS placed in the clcctni11horct1L' chamber. I he -.l1de 11.1-. u innectcd to !hr buffer 11 ith a wick. The chamber contained !Ill' dcclrndcs. \\ h1ch 11crc c11nncell'd tn !he 111,,11 11 L' terminal while the antiscra to the ncgati\'C cnd I he .1nl1gcn 1\ells \1crc lilied 1\ 1th !he sample Il l be tested 11hiic !he Other l'O\\ of wells \\US lilied 111th antiscra spcrlfiL tn ronl and lllOll th disease \.irus (fl\1DV). Electric field was placed across the slide such that the antigen 11crc negati vely charged and' the antibody positive!) charged. The charged reagents migrate to opposite direction where the antigen and antibody arc homologous or spcci fie to each other. and react in optimum concentration, precipitin lines .\.\•ere formed. (Bellhouse, el al. ( 1982) T issue Cult ure Systems four cell culture systems were used: Baby hamster kidney (Bl IK), strain 2 1, clone 13 and vcro cells (established cell lines) and Bovine kidne) (BK) and Lamb Kidney (LK) cells (Primary Cells) were grown I O</ml) in Eagles medium with I 0% tryposc phosphate broth. I 0% feta l cal r scrum and antibiotics ( I 00 units per ml or penicillin. I 00 units per ml polymixin B and 0.002g per ml streptomycin). The cells were gro\.\n in Rou-. flasks, incubated at 37°c units complete monolaycr is formed. Virus lnfectivity Titration In Tube Cell Mo nolaycr I .Om! or each of cell suspensions of 111 IK - 21. l'ero. BK and LK cells were grown (3.0 x 105/ml) in cell culture screw capped tubes unti l they become confluent. The virus suspensions were diluted I 0 - fold serially in PBS (I 0·1 - I o·8) The cell culture tubes mono layer were inocul ated with I ml per tube of appropriated 1 irus dilutions All infected tubes and controls were incubated at 37°c for 24 to 72 hours and observed daily for cytopathic effect (CPF). The presence' or absence of CPE in infected tubes was scored and virus log1o TCID5o titre was determined by Reed and Muench method. ( 1938). RESULT AN D DISCUS, JO'\ FMD vi rus scrot) pe, SAT I infcctivit) 111 the cdl systems ma1nla1ncd the highest yield in Bovi ne kidney cells followed by BHK - 21 cells (Table I). A titre range of 5.60 - 6.85 log1o TCID5o/rnl was obtained in BK cells as compared to 4.45 - 5.60 log1 TCID5ofml in BHK - 21. However the virus grew in all the cell cultures tested but had a low yield in vcro (35 - 5.25 log10 TCIDso/ml) and LK (3.25 - 4.5 log10 TC IDso/ml) (Table I).  Cl111~ \I UCdll a11d ( illlll\\il" ( 2005) N1g .I 1!1n1cch I(, (I) I 12 . 120 11 S TABLE I: FMD Virus SAT 1 infccti v ity assay in cell culture systems F ID \'i rus lo I 0 TC! D 50% End m int Titre in cell sys tem . SAT I VIR s IN IlHK-21 IN VERO IN BK IN LK STRA I 'GS I -· 5.20 4.25 5.80 3.25 Nig 1/9..J ' ig 2/94 5.50 4.35 6.5 .D I Nig 2/94 5.60 4.50 6.00 I 4.50 Nig 6/95 5.25 5.25 6.75 ND :--J ig 8/96 -1.50 4.00 5.60 ND I Nig 5/97 4.45 I]) 5.63 3.25 Nig 1198 5.25 3.50 6.85 I ND ig 2/2000 5 . ..JO 3.75 5.75 'D ND: Not determined l' hc IO\\CSl titre )ielded in 13K cel ls \\Ith ~ /\ 11 l·i\1D Viru!'. duri ng the stud) \\as higher than the highest titre obtained '' ith Bl IK - 21 cell c; (:' 60 log1o TCfD,r/rnl) 1"11c S/\T 1 strn1nc; (N ig. 1/98 and 1 ig 6195) gave rcla ti \'cly higher titre.., in BllK 21 and 111--: Cells hut 1101 uetcrmincd in l ,K cells (Table I) due lo co111amin,111nns. \ lca11\\ hile S1\ I I 'it rains succcssl'ull~ cultured in l.K cel ls generally yie lded Im" titres compared ll) other cell cullrn1.·s used. The St\ 'I 2 infectivit) assay in the di1Tcren1 cell cultures~ stem" ~ 11.'ided li tres'' h1ch 11c 1101 much significant!~ different from each other 1n 11l IK 21. V1.·ro ,1nd 11K lclls (Table II ) TABLE II: F;\11) \ ' IR US SAT 2 li\'FECTI\ IT) \~S \) 1.'\ CELL ('l' I '1 l RE SYSTE:'-1 ~ : AT 2 \ ' IJHS' (,'\'B ill\: - 21 (\ \ ERO . (,'\'Bl' . (\ I.K : TRA INS ____ I :.; i g I '9 5 5. 5 0 4. 7 5 t 5.50 l.O :tg.395 480 1 1) 5.00 \,I) I 1g 5 95 4.25 3.8S 5.55 :--:D :\ig 2 ·97 6.}5 5.85 5.05 I f) 4.75 5.00 5.00 J.8 :-\ig 3 Q 5.50 5.00 ..J .75 NfJ l\D: ~ot determined.  ChuL \\ 11ccto and (iom\\ .11~ ( 2005 ) '-.; 111 _I n IUICl.'.h 1<1 f I l I I~ 120 I I(> I lowever. FMD virus SAT 2 strain (Nig 2/97) ga\·e lhc highest titres in the three cell cultures (Bl IK 6.25 log1o TCID,o/ml. \'ero 5 85 log111 I CID511/ml. BK 5.(15 Log1o I CID~c/ml) but was not cultured in LK cells due to contaminations. SAT 2 growth 1n growth in vcro cells in overall assessment was better that SAT 1 growth in the same vcro cells. Comparing the growth of SAT 1 and SAT 2 in Bl IK and BK cells. there was a significant difference in titres of SAT I grown in 81 IK and BK cells while culturing SAT 2 in the same cell system docs not show rromincnt differences in titre . This finding agreed with the result obtained by l·crris ct al ( 1984). Abcgundc (1987) and l·crris and Donaldson ( 1992) while growing SAT 1 and SAT 2 in Bl !K - 21. BK and Bovine th~ roid (131 YJ cells also obtained lower SAT 2 strains than from European strains. The high litres or Si\ r 1 in BK cel ls. may be attributed lO its earlier adaptation in cattle since all the strains were the SAT I and SAT 2 generall y yielded low titres in lamb kidney cells (Table I!). Eric ct al ( 1998) found that the most sensitive cell culture type for detecting FMD virus can vary therefore. depending both upon virus strains and prc\'ious passage in the host. Although BHK - 21 cells arc recommended and recognized as the standard cell culture for Ff\!D virus cultivation. Donaldson ct al ( 1970) found that Bl~ and lnRS cells were the mn:-,t sensitive assay system of detecting FMD , ·iru~ adartcd lo cattle (Table Ill & I\').  Chuk"ucdo and Gom"alk (2005) N1g J Biotcch 16 (I) 112 · 120 11 7 TABLE Ill: TITRE OF SOME SAT I STRAIN OF FMD IN BTY IBRS AND BHK-21 CELLS · VIRUS STRA INS 01 it!. 418 I : ~1g 5181 Ni, 10 81 Nig 11 /80 i' 155/68 I Nig 1168 ig 1/68 *Mean of titration TITRE IN BTY TIRE IN IBRS CELLS. LOG TC ID50 I CELLS LOG TCI 1)50 6.00 6.37 6.82 6.80 6.87 (J.00 6 41 6.56 ' 6.i.10 I I 6.44 J.£:.?2 6.48 - - . ----- --TIRE TN BHK - 21 CELLS LOG TCI DR50 3.24 119 ... 3.4 1 4.25 4.56 5.25 4.38 ·--- --I I TABLE IV: TITRE OF SOME SAT 2 STRAINS OF F\1D IN BTY urns AND BHK - 21 CELLS VIRUS STRA INS TITRE IN BTY 1 l"IRE 11 IBRS CFLLS-.-Tlfff: IN 8HK - 21 CELLS. LOG I OG TCI 050 ~CELLS LOG TC! TCID50 ~O ~-""------+-6 __ .2 _____ __.r 6~ 5.47 _ -j 4.8 4.44 2.87 ........ ~--------+- -r-;:-- -- . i 5.4 • 5]_1 --- 1-5.31 -6.0 6 44 ."\ 4..J - ') ------ , (Y\ I' ()( )._ 1.11 I ' Nig_l/80 __ _ Nig 5/68 L _j_ *Mean of 3 titration ----1 These other cell systems that surpnrts the grn\\th nl thc~c '1rus scrot) pcs ma~ scr\c as ad.1t1111h ''hen 81 IK 21 cells arc not a,·ailahk l'hL' use Pl' 11nmar) cell culture for r:;-.1[) 'irus grcll\lh and isolation should be done with caution because of the problems or ach cnt1t1ous agents thal may serve as contaminqtions. The ti tre of the vi rus in LK cells ma} be improved after adapta11on through series of passages in LK cell monola~cr. The virus yields after cul tivation var) from one cell system to another. All the strains of the S,\T 1 and SAT 2 used presented a typica l FMD virus CPE pattern in the cell cultures. In thi s work reported here the serologica l assay or cel l culture supernatant re' caled the presence of tuo n1aJor anugcns produced as a result or the F.MD 'irns replication in the.: culture; whole vi rus ( 146s) and virus infectious antigen (VIA). Sirnilarl). Sellers (1980) reported the presence of 16-ls and I 2s structural capsid proteins and VIA antigen in fMD in rectcd tissue culture or  l l111k\\U\0 \l\1 i1t1J (nlll1\\alk 1_'1111'\ ''i:~ li11 \· ... 11 1(1 111- .'t 11 !1 :1n1111als. Antibud11.:s to 1-l(>s and 12s prol1.:1 11s 1s l) pt: :-,pt:cilic \\h1k \'I.\ an11bod) 1s not ... pccil"1c and antibod) product:d against VI/\ antigen do not react with purilil.!d virus or its submit. It h,1s bt:t:n rcportl·d th<1t tht: \ ' I.\ 1:-, :-, l1li1111 l\l lk' \irns po l)mCrase VP 56 on polya1T)l,11111de gi.:I electrophoresis (Nl.!\\111an. cl al 1979) wh ile Bru\\ll (1981) 1den1ilicd VI/\ as RN1\ dependent RN/\ polymerasl.' and shu11 tu contain majo1 'jrus cutll.'d protein or mol. \Vt. 56,000 b) double immuno diffusion (DID) stud1l.!S in sera. The er: test has been the method 1110Sl widely used lO different iate PMIJ virus strains (Pereira, 1978). /\!though it can not diflcrcntwte b..: t11cen non-immunogenic and immunogcnic antigens (Cowan, 1973). In this stud) it 11a:; used tu runher con lirm the serotypcs. S/\T I and SAT2 identified by C IE Cl able V). 1'11c Cl!: and CF 1..:m rnncluc tcd on the anti scra sho'"ed that over 50% of the VIA positive sera contained S/\T I antibodies ( 145/229, 47.23%) as compared 10 SAT 2. ::i1milarly O\e r 50°10 or the Cl! · conlirmed ' /\T I and SA I 2 antiscra contained CF antibodies (32.25 out or 47.23 and 13.36 out \lr2 I .50. !'able V). TABLE V: ANTISERA - Fl\ID SPECI FIC ANTIGE 1 REACTION BY CI E AND CF TESTS --NNO. 017 NO. OF O. OF f NO I :-\0. ' l\o. ' '\O PO I rl\ 'L TO /\N IM/\L ANIMAi. Sl·:IZ/\ I POSI I !\' I: POSITIVL PO ITI\ er rl. I INFECTED INFl ·:CTE COLLLCTI: rn ,.,,, l'O SAT! l IO :\I D D /\ l' IGl: N /\NTIGE:'\ 2 (%) ( o,o) A '\ f' IGE I \ (%) - I ---s ,, ·1 S,\T2 Plateau 60 47 31 18 1 8 I(%) --~~o_)_ Niger 48 40 38 IS 1-l 15 3 lgbeti 71 64 -11 ] .J 6 II 8 Bauchi 23 23 \ 17 12 5 ..,.., ' J Gem bu 51 44 35 26 9 9 ' ' Azare 39 31 29 23 2 17 7 Yo la 74 45 29 11 16 15 2 Bokkos 15 13 9 ' 6 9 .) 11 I 1 4 - -~---335 307 229(74 .59) l-t5(47 23) 66 (21 .50) 99(32.25) --) = Showed % Values. This Sllld) results ~hO\\ S that a c(fC<ll J c,11 or variation 1;-; found in the growth characteristics or a serological l) pc of F'vl I) ' rus Therefore there could be more information in il1\CSligating furthe r th..: u~c ur other Cl' il S~'>\.''lh ,I, an altenhlll\t: to BllK cdb in !· \ID \lrllS 'itud1..:s. ,\CKNO\VI .EDC E.\11-:\T We 111sh to . 1d.111> \\k,l~l· thl· ""'1.,1.111, ,· 111 the· t..:d 1111c1a11. 0.lr Obadiah Shuark)cs. Dr . .I. lhu 11h\l pruoi' rL-;1d th,· p.1pn .111,I \11 \\ 1111.111 \ lh1)111 h11 t)pcd thl· l\lanuscript 41 (13.36)  119 REFERE:\'CE . J\begunde. A .. ( 1987) Epide111 iology of I· MD. Ph. D. Thesis. J\ h111adu Bello University. Zaria. :\begunde. A. CrO\\"thcr . .I. R.: E7eokoh. CD: and Umoh . .I. U. (1988). Antibodies to VIA an tigens in 'igcri a Cattle . Rulkt in nf 1\ni mal I leal th Production in Afri ca 20 (J) 62 - 67. /\hcgundc. 1\ .: Chuk\\uedo. 1\. /\. and Cionl\\alk. ". I'.. (2003) Qualit) E\'a luation of two FMD Vaccines prepared fro111 local isolates of serotypcs S/\ T I and SAT 2 antigens and Montanide ISA 206 for111ulations. 1ig - .I. Biotechn. 14 (I) 29 - JS. !3cllhousc R: Baker K. 13 and Hedger. R.S ( 1982) Counter i111111 uno electrophoresis in the diagnosis and serological su1Yeillance of swine \esicu lar disease. Vet. Rec. 11 0. 357-358. !lorn n. P. ( 1981) /\ppl1ca11on or agar gel 1m·1:1pitation lesls to the stud) or the virus of Fool and \1outh disease Virolog). 5. 13' 1'14 Chukwucdo. 1\. J\.: 1\ bcgundc. /\ and Cionl\\,tlk. ~- I (:200:1) Studies nn the current \tatus nr Foot and ~louth Disease (l ' \11)) Vin1. outbreaks 111 '.\'ig .. I n1otcchn 14(1) ~2 28. Cowan. K. I. (1973) 1\ntibody response lo \'iral antigens. 1\<hanced Immunology. 17. 195 253. Da\ic . .I (1<)64) /\ complcmrnl fixation ll'l·l1111qt1c fp1 the quanl1t.1l1\C 11wc1..,111u11cnt or:111t1grn1L difTercnC\.!S bet\\'Cen strains Pi lhe \ ll'llS o r i"(H1l-,111cl-111outh tit'>C<lSC JOllrll<ii nf I lygicnc 62.-l I 0 -l 11 Donaldson. t\. I.: I lern1111an. K./\ . .I: Parl-er .I .md Sellers RI ( 1970) I urthcr 1n\es11g.111ons on the airborne excretion or l·oot md \lnuth D1.c.1..,c \ "1rus . .I. I l~g C.1111h 68. 557 r64. Ezeokoli. C. D.: Abegunde. /\ . .I. Umoh . .I. l and Addo PB. ( 1988) 1::piderniology of 1:oot and ~ l outhdiscasein ' igcrial.1\-c-.1ock.I \ "1rol\lcthodsl4(1)121 127 Eric. B.. ocmi. S., Nuira V., Carmen \1.R .. I \\'aid B. and Esteban D. ( 1998) fultiple Virulence Determinants, of Foot and Mouth disease virus in cell culture . .I. Virol Vol. 72, (8) 6362 - 6372 . rerris N. P. Donaldson A. I. Barnett I. T. R. and Osborne. R. W. ( 1984) Inactivation, Puri fi cation and stabili ty of 1465 antigens ,b f Foot and Mouth Disease Virus for use as reagents in the Complement Fixation Test. Rev. Sci. Tech. Off. Int. Epiz. J (2) 339 - 350. Ferris. N. P and Donaldson/\. I. (1992) The World reference Laboratory fo r foot and Mouth Disease. a review of thirty-three years of act ivity (1978- 1991). Rev. Science off Int. Epi7. 11(3) 657 - 684.  Ch:1k11ucdo and G<'lll" alk (2005) N1g J l31ntcch 16 ( I) 11 l · 120 120 Newman .I. f. I·:. Cartwright, f3 .. Doc!. T. R. and 13rown, f. ( 1979) Purification and identification of RN/\ dependent RN/\ polymerase of Foot and Mouth Disease Virus Journal of Gt.:n Virolog~. -tS 497. Pereira. 11. G. ( 1978) Antigenic variation in relation to epidemiology and control of foot and mouth disease. 13ritish Veterinary .Journal. 134 . 28 - 33. Recd. L. T. and :vtuench M. ( 1938). Simple est imate calculation Am . .1. I !yg. 27:403. S,1111son I~. I.. (199-t) 1'11c Epidcminlogy lll" hiot .ind i\ louth Disease- Implication !"or nc" lea land. Ne\\' /ea land \'ct .I -t 2. 4 I S \ Sherry ' .: Pe ter: M. \V. and Barry B. (2000 ) I ligh effic1enC) ut ili7at ion of the Bovine 133 as a receptor fo r Foot and Mouth Disease Virus is dependent on the Bovine 83 Submit .I . Virol. 74 ( 16) 7298 - 7306 Seller. R. F. ( l 980) Quantitali\C aspects of the spread of foo l and Mouth disease. Veterinary l111llctin. 41. 43 1 439. 

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Growth comparison of Nigerian strains of foot and mouth disease virus (FMDV) types SAT 1 and SAT 2 in BHK, BK, Vero and LK cell culture systems

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Growth comparison of Nigerian strains of foot and mouth disease virus (FMDV) types SAT 1 and SAT 2 in BHK, BK, Vero and LK cell culture systems

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