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SERO-CONVERSION AFTER ORAL POLIO VACCINE* Usx^ D. H^lxo^s, A,A. P^~u^g ^No V.L. J^~I^OXgD^R

~"~pur ,The incidence of

poliomyelitis has decreased considerably not only in the developed e o u n t r i e s ~ m o s t l y in temperate z o n e s - - b u t also in certain tropical and semitropical countries where satisfactory vaccination p r o g r a m m e s with Dive oral polio vaccine has been instituted (Dr0zdov and Cockburn 1971). , Ample evidence exists that i m m i n e n t epidemics could be prevented and existing ones terminated or at least controlled with the aid of this vaccine, in | . certain tropical and semitropical areas ( A r u m a n a y a g a m znd Mend,.'.-!965, Witte t| al. 1965). In spite of these epidemioiogical observations, a n u m b e r of virological studies have shown that in w a r m climates the efficacy of live polio virus vaccine, measured by the sero-conversion rate was much lower than that obtained in temperate climates. Reports from I n d i a (John and J a y a b a l 1972), I r a u (Nategh etal. 1970), T h a i l a n d (Sangkawibha 1969), Singapore (Lee 1964), Hongkong (Franklin and Robertson 1965), U g a n d a (Domok et al. 1974) and Nigeria (Poliomyelitis Commission of 1966. Montefiore eta/. 1963), deserve special mention in this respect. In view of the continued high incidence of poliomyelitis in Nagpur noted in tile course ot earlier investigations (Hardas and Waiker 1974), and the lack of data on seroconversion following immunization with *From the Department of College, Nagpur. Received otaJune 16, 1978.

Microbiology, Medi, al

live oral polio vaccine (OPV) a s t u d y _ " ~ carried out to evalLate the s e r o - c o n v e r f l l ~ rate in the healthy paediatric p o l : / U h t t ~ o f Nagpur. T h e present paper gives an a c c o u n t ~ the study and results are discussed in r e / tion to the data available from differe-alm parts of the country.

Material and Methods T h e study of Jseroconversion after O P l m was carried out for one year from v.Jaiatt/J~ to December, 1974. Prevaccination b l o l m samples from 78 healthy children betwemm the ages of 3 months to 3 years w e r ~ collected They were given 3 doses o R trivalent oral polio vaccine, (Sabin) w i t 1 titre 106 T C I D 50 for polio 1,106 T C I D 51111 tbr polio 2, and 105-s T C ! D 50 for polio 3 at intervals of 4 weeks and post vaccination~ blood samples were collected 4 week~ after the third dose. T h e vaccine was received by air in a thermocole parcel packed in ice. After arrival, the vaccine was kept a t - 2 0 * G until used. It was carried to tile place of vaccination in insulated ice boxes. The virus titre of the vaccine was tested trequently and was found to be satisfactory. T h e children were carefidly supervised to make sure that the vaccine was swallowed; if it was not~ another dose of vaccine was immediately administered. Blood samples were collected by venepuncture in sterile containers. Sera were separated and stored at - 20~ tmtil used in the test. Sera were inactivated at 56~ for 30 minutes before the test.

IIARDAS I..T AI..-- gEl(o-CONVERSION A F I E R ORAL POI.IO VACCINE

Strrtra neutrali.'.atton teJt

Antibodies to polio virus ,.,,'ere detected by the neutralization test in monkey kidney dtsue c u h u r e prepared by the method of ~,odian (1956) and Younger (1954). Th~ 4get was performed using all the 3 types 0]" polioviruses in the titre of 100 T C I D 50 per 0.1 ml and an equal a m o u n t of 1.10 di!uted sera. T h r e e tubes per antigen were used with 0.2 ml of inoculum per tube along ~ i t h control of virus titration, i~rum toxicity, and cellular morphology. Seraneutralizing the cytopathic effrct were taken as positive.

R e s u l t s and D i s c u s s i o n '.,~,o-conoersion after uar

The T a b l e shows seroconversion in 78 children studied, i.e., 92.3 per cent from :28.1 per cent for polio 2, 83.3 per cent from 28 2 per cent for polio 3 and 57.6 per cent from 28 2 per cent for polio ! o f tbe prevaccinated sera of the 3ame individuals. The n u m b e r of triple negative children was also r e d u c e d from 46.1 per cent to 2.6 per cent, after 3 doses of oral polio vaccine. O u r results compa.re well with other studies from India. Ghosh a al. (1970) m their study of 87 infants from the Delhi population reported a sero-conversion of 40,2 p e r c e n t , 74.7 per cent and 50.6 per Cent for poliovirus I, 2 and 3 respectively after 3 doses of OPV. T h e i r resnhs were further confirmed by the study of C h a u d h a r y a al. (1973) from a similar p o p u l a t i o n at Delhi. They reported a sero-conversion rate of 63.4 per cent, 74.6 per c e n t and 67.6 per cent for poliovirus 1, 2 and 3 respectively. Neither of these sero-conver|ion rates is comparable with those usually found in temperate climate after a d m i n i s t r a t i o n of

311

OPV. For examl,ie , liorstmann t t a l . (1961) found 92.100 and 88 per cent sero-conversion for polio I, ~2 and 3 respectively. Several factors }]ave been reported to be responsibie for poor sero-conversion in the tropics, of which interference between the enteroviruses and the vaccine strain is the most a g r e e d upon factor as suggested by Domok et al. (1974). The same authors in the course of their investigation to study factors affecting the efficicacy of oral polio vaccine, also revealed the presetlce of an inhibitor substance in the alimentary tract. This inhibitor acts against the muhiplication o f vaccine virus .in the initial stage which m a y be blocked by horse serum containing antih u m a n immunoglobutins. However, itl effect on the response to type 2 and 3 poliovirus vaccine and trivalent vaccine has not been established. The possible adverse effects prodl:ced by breast feeding at the time of oral polio vaccination have been excluded by J o h n el al. (1976) in their recent study, and also by Domok a al. (1974 in which breast fed and artificially fed children gave a comparable re~ponse in w a r m climates. The possibility that children in warm climates develop intestinal resistance after infection with polio viruses without humoral antibody response was raised by Sabin at W H O informal meeting on poliomyelitis in the tropics, held at Helsinki in 1968 (Domok et al. 1974). Tiffs possibility was also excluded by Domok a el. (1974) by their extensive study where in seronegative children a close correlation was obtained between the excretion of polioviruses and a n i b o d y conversion even after revaccination. Ogra etal. (1968) have studied the

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~gDAS z'r At..--sF.Ro-co.~'.'l itsiox ^r rr:tt ogAr, l ' O L I O VAC{INE, concept of local i m m u n i t y and tlie possible r01e of the live vaccine of p o l l , m y e l i t i s by the study of i m m n n e g l o b u t i n response in lerum, duodenal secretion a n o nasal tcashings. T h e y reported the i3reser:.ce of secretary a n t i b o d i e s (IgA) in additiott to i~r a n t i b o d i e s (IgG, I g M a n d ]gA) after live oral p n l i o v a c c i n e as against only serum a n t i b o d i e s produced by the killed vaccine. J o h n at a/. (1976) r e p o r t e d a satisfactory respon.~e xs ith t r i v a ] a n t

very oral

poll v a c c i n e Gf l0 fold e n h a n c f d potency. It may be c o n c l u d e d that in the tropics, ~ u l t i p l e doses w o u l d seem to be necessary for satisfactory sero-co~version, which will overcome i n t e r f e r a n c e of the enteroviruses lit well as the i n t e s t i n a l i n h i b i t e r described

313

Franklin, G.C,, Roberuon, M.J. (1965). A mass %atfin&iion carnpalgn against |,otlomTclitiJ using the Sabin oral vaccine. P=blic H.alr (to.doa) 79, 81.

Ghosh, b., Kuma~i, 3., Balaya, S. (1970). Antibody te=pof,se to oral polio vaccine in infancy. Indtan Ptdlatp. 7, "IR.

liardau, M.D., ~,%aiker, AS. (19';'4). Pilo:. :.utvey of disabled children in and around Nagpnr. Indian .7. l'r 41, 27t,. Horstmann, D M., paul, J.R., McCrea, Godenne, (1961). Immunization of preschool children with oral vaccine (Sabin). .~AMA 178,693. john, T.J., Devarajan, L.V., B,ilasubramanyan, A. (1976). lmm.nlzatlon in India v.ithtrivalent and monovalent oral pollovirus vaccine of enhanced potency. Bull WHO, 54, i 15, John, T.J , Devarajan, L.V., Luthert L., Vijaya9 rash.am, P. (1976). Effect of breast feeding on serorestmnse of infants to oral poliovirus vaccination. P, diaOic#

earher.

.57, 47.

Summary S e v e n t y eight p a i r e d sera were studied for s e r o - c o n v e r s i o n after oral polio vaccine, in c h i l d r e n b e l o n g i n g to the age g r o u p :3 months to 3 years. S e r o - c o n v e r s i o n was highest i e . 92 3 p e r c e n t for polio virus 2, 83.3 p e r c e n t for polio virus 3 a n d 57.6 p e r c e n t for polio virus. T h e n u m b e r of triple n e g a t i v e c h i l d t e t t was r e d u c e d to 2.6 per cent from 46.1 per c e n t after g i v i n g 3 doses of oral polio v:tccine.

John, T., Javabal, P. (1972}. Oral polio vaccination of children in the tropics. Am .7 Eeidera 96, 2q53. Lee, L.H., Limk, A., Tye, C.Y (1964). Peeve.. tie. ot poliomyelitis in Singapore by live vaccine. B.M~ 1, 1077. MonteBore, D G., Jamioson, M F.. Collard. P.~ Hugh, Jolly. (19",3L Trial of type I oral polio vaccine (Sabin~ in Nigerian children. Brit. M,d. J. 2, 1569 Nategh, R. (1970), Ma~s trivalent oral polio vaccit~atior~ i~, primary school age children iu Teheraa. TFOP. GLog. Mr 22, 303. Ogra, P.L, Karzon, P.J., Righthand, F.,Mac. (;illivray, M (19t,3y lmrnunoglobulin with liveand inactivated polio vaccine and natural infection..,V,w Eng. ~ Med. ~79. Poll.myelitis Commi~ion o( the Western Region, M,nistly of Health, Nigeria. (190~). Poliomyelitis vaccination in Ibadan, Nigeria, during 1964 with oral vaccir,e (~,abin strain ). hull IV/tO, 3'1,, 8*0,5. ~angka~ibha, N. (1969~ Antibody response and virusexctetio, after oral vaccination with trwalent live poliomyelitis vaccine. ) . ,~ded. Assn. Thai/and, 52 , 701. Witte, J J., Page, M l.,Celfand, H.M. (196.5). Control el type I epidemxc in British Guiana. Big/.

Refrreneea Arumanayagam, I'.. l~,tex,dis. N.M.P. (1965). Outbreak of poliom~eliti, i. (;eylon in 1062. Am. 7. ]"top. Mrd. Hy~. 14, 4.10. Bodian, I). ~l.~d'~L r.liovi~us in chimpanzee tissues after virus feedit,IL .4.,..]. H~'I. 641. 181. Chaudhary, D.S., N..ilt, N N., Vi.jayan, Bindu. Raghaban, N.G.S., Paul. S. (1973). Poliomyelitis vaccination of infaut-, t,te0n mut~iration status and ~roco= version. BuLl. If'I/O, 48, 19re. Domok, I.M S.. lt=l=~at=, O A . , Fayink=, N., Skrtic, Soneii, A.D , I let I,,t,,l, p.S.E.G. (1974). Factors affecting the ef~cicy t,I lave polio virus vaccine in Warm c/imates. Bull II'I/fP, 51, 3~t3. Drearier, S.G., (:.vkbu,n, W.C. (1971). Pohomyelitis in the d0veh,ped and develc,ping countries. Pan American I lral,h Organization, 163-170. (Scientific Puhlicatio. No. 226}

W.tt.O 33, 1.

Youngner, J.S. (Ig~9). Monolayer ti~ue culture. Prec. Sor Erprr. Biol. & Mcd. &5, 202.