W O R L D H E A L T H O R G A N I Z A T I O N V I R / Y F / 7 1 . 1 6
O R G A N I S A T I O N M O N D I A L E D E L A SANTÉ
E X P E R T C O M M I T T E E ON YELLOW F E V E R
E n t e b b e , 9-15 March 1971
INDEXED
IMMUNOLOGY
A n t i b o d y r e s p o n s e s a f t e r n a t u r a l i n f e c t i o n and a f t e r v a c c i n a t i o n
b y
W i l b u r G. Downs, M.D.
Department o f E p i d e m i o l o g y and P u b l i c H e a l t h Y a l e U n i v e r s i t y S c h o o l o f M e d i c i n e
N a t u r a l i n f e c t i o n w i t h y e l l o w f e v e r v i r u s i s f o l l o w e d by a p p e a r a n c e o f complement f i x i n g ( C F ) , h a e m a g g l u t i n - i n h i b i t i n g ( H I ) and n e u t r a l i z i n g (N) a n t i b o d y . T h e r e i s a l a c k o f i n - formatiçn c o n c e r n i n g t h e p r e c i s e t i m i n g o f a p p e a r a n c e o f s u c h a n t i b o d i e s and t h e c o m p o s i t i o n o f s u c h a n t i b o d i e s i n t h e human h o s t , b u t by i n f e r e n c e from s t u d i e s i n a n i m a l s i t c a n be assumed t h a t N and HI a n t i b o d i e s a p p e a r w i t h i n a few d a y s o f i n f e c t i o n f o l l o w e d s h o r t l y by a p p e a r a n c e o f CF a n t i b o d i e s . N e u t r a l i z i n g a n t i b o d y i s f i r s t d e m o n s t r a b l e on t h e f o u r t h o r
f i f t h day a f t e r o n s e t o f i l l n e s s and t h e peak l e v e l may n o t be r e a c h e d u n t i l t h e f o u r t h week o r l a t e r . B e r r y e t a l . (1931) i n a s t u d y o f l a b o r a t o r y a c q u i r e d i n f e c t i o n s , m e n t i o n a c a s e i n w h i c h b o t h v i r u s and N a n t i b o d y were s i m u l t a n e o u s l y p r e s e n t i n t h e b l o o d on t h e f o u r t h and f i f t h day o f d i s e a s e . Downs e t a l . (1955) r e p o r t a c a s e where a v i r u s was i s o l a t e d on t h e e l e v e n t h day o f i l l n e s s , a t w h i c h t i m e , and a l s o l a t e r , a l o w l e v e l o f N a n t i b o d y was p r e s e n t . The a n t i b o d y l e v e l was so l o w t h a t i t prompted t h e s t a t e m e n t " i f v i r u s h a d n o t b e e n i s o l a t e d ,
t h e d i a g n o s i s o f y e l l o w f e v e r c o u l d n o t have been made on t h e b a s i s o f t h e s e n e u t r a l i z a t i o n t e s t s " .
The N ( a n d H I ) a n t i b o d i e s p r o d u c e d f o l l o w i n g i n f e c t i o n p e r s i s t f o r l o n g p e r i o d s o f t i m e , a l t h o u g h t h e r e may be some d r o p i n a n t i b o d y l e v e l s o v e r a p e r i o d o f y e a r s . The i n d i v i d u a l a p p e a r s a l s o t o have a l i f e - l o n g i m m u n i t y t o YF v i r u s . I t h a s been p o s t u l a t e d t h a t t h e l o n g p e r s i s t e n c e o f a n t i b o d i e s may r e s u l t from a p e r s i s t i n g v i r u s i n f e c t i o n . T h i s h a s n o t been p r o v e n .
T h e i l e r and C a s a l s (1954) p r e s e n t a d e t a i l e d s t u d y o f H I , CF and N t e s t r e a c t i o n s i n y e l l o w f e v e r c a s e s ( a l l d i a g n o s e d by v i r u s i s o l a t i o n ) o r i g i n a t i n g i n T r i n i d a d and B r a z i l . I n p r i m a r y i n f e c t i o n s ( i . e . i n i n f e c t i o n s i n i n d i v i d u a l s who had no d e t e c t a b l e g r o u p B a n t i b o d i e s i n t h e a c u t e phase serum s p e c i m e n ) , t h e HI r e s p o n s e i n a l l c a s e s was h i g h e r f o r a YF a n t i g e n t h a n f o r a n t i g e n s o f s e v e r a l o t h e r v i r u s e s o f g r o u p B a l t h o u g h c r o s s i n g a n t i b o d y was d e t e c t a b l e i n most o f t h e c a s e s s t u d i e d . A s i m i l a r s i t u a t i o n o b t a i n e d f o r t h e CF a n t i b o d y , a l t h o u g h t h e r e was c o n s i d e r a b l y l e s s c r o s s - r e a c t i v i t y s e e n . I n N t e s t , t h e c r o s s - r e a c t i v i t y w i t h D I , D2 and I l h e u s was e i t h e r m i n i m a l o r n o n - e x i s t e n t , w h e r e a s t h e r e was d i s t i n c t YF n e u t r a l i z a t i o n i n a l l serum s p e c i m e n s t a k e n more t h a n t h r e e d a y s a f t e r o n s e t o f d i s e a s e .
In s e c o n d a r y c a s e s ( i . e . c a s e s i n w h i c h g r o u p B a n t i b o d y was p r e s e n t i n t h e a c u t e phase s p e c i m e n s ) t h e s e r o l o g i c a l r e s p o n s e was d i s t i n c t l y d i f f e r e n t . A h i g h l e v e l o f HI and CF
a n t i b o d y was s e e n e a r l y , a n d c r o s s i n g a n t i b o d y t o o t h e r g r o u p B v i r u s e s a l s o a p p e a r e d e a r l y , and a t t a i n e d l e v e l s t o c e r t a i n o f t h e v i r u s e s a t t i m e s s u r p a s s i n g t h e c o r r e s p o n d i n g YF a n t i b o d y l e v e l . I n such c a s e s , i d e n t i f i c a t i o n o f t h e i n f e c t i o n by HI o r CF r e a c t i o n , i n a b s e n c e o f v i r u s i s o l a t i o n , m i g h t be i m p o s s i b l e . T h i s i s t h e f a m i l i a r " a n a m n e s t i c r e s p o n s e " w h i c h h a s
The issue of this document d o e s not constitute C e document ne constitue pas une publication, formal publication. It should not be reviewed, II ne doit faire l'objet d'aucun compte rendu ou a b s t r a c t e d or quoted without the agreement of r é s u m é ni d'aucune citation sans l'autorisation de
the W o r l d Health Organization. Authors alone l'Organisation Mondiale de la S a n t é . Les opinions are responsible for views e x p r e s s e d in signed e x p r i m é e s dans les articles s i g n é s n'engagent articles. que leurs auteurs.
V I R / Y F / 7 1 . 1 6 p a g e 2
b e e n f r e q u e n t l y n o t e d i n v a r i o u s g r o u p B v i r u s i n f e c t i o n s . A s i g n i f i c a n t d e g r e e o f d e v e l o p m e n t o f c r o s s - N a n t i b o d y t o D I a n d D2 was o b s e r v e d . T h e p o s i t i o n w i t h r e s p e c t t o I l h e u s v i r u s w a s n o t s o c l e a r , p o s s i b l y b e c a u s e m o s t o f t h e p r e - e x i s t i n g g r o u p B e x p e r i e n c e w a s w i t h I l h e u s v i r u s , p r e c l u d i n g t h e p o s s i b i l i t y o f a " c o n v e r s i o n " .
S p e n c e e t a l , ( 1 9 6 1 ) d e s c r i b e two y e l l o w f e v e r c a s e s i n p r i o r g r o u p B i m m u n e s , b o t h s h o w i n g a marke,d d e v e l o p m e n t o f g r o u p B c r o s s i n g i n HI a n d C F . I n o n e c a s e s t u d i e d i n NT, t h e c o n - v a l e s c e n t sei-um s p e c i m e n ( 4 0 d a y s p o s t - i n f e c t i o n ) n e u t r a l i z e d 2.8 l o g s m o r e o f Y F v i r u s t h a n d i d t h e a c u t e ( f i v e d a y ) s p e c i m e n . H o w e v e r , t h e c o n v a l e s c e n t s p e c i m e n a l s o n e u t r a l i z e d 1.3 l o g s m o r e o f S L E a n d 1.6 l o g s m o r e o f I L H . T h e i n d i v i d u a l was s o l i d l y immune t o d e n g u e i n b o t h s p e c i m e n s .
T h e a n t i b o d y r e s p o n s e f o l l o w i n g y e l l o w f e v e r i m m u n i z a t i o n w i t h b o t h t h e F r e n c h n e u r o t r o p i c (FN)" s t r a i n o f v a c c i n e a d m i n i s t e r e d by s c r a t c h , a n d by t h e 17D v a c c i n e a d m i n i s t e r e d by s u b - c u t a n e o u s i n o c u l a t i o n o r by s c r a t c h h a s b e e n s t u d i e d by a s e r i e s o f l a b o r a t o r i e s o v e r a n u m b e r o f y e a r s . T h e c h a p t e r b y S m i t h i n " Y e l l o w F e v e r " ( S t r o d e , e d . , 1 9 5 1 ) s u m m a r i z e s t h e p o s i t i o n a s o f t h a t d a t e . I t was a p p a r e n t t h a t t h e a n t i b o d y r e s p o n s e f o l l o w i n g i m m u n i z a t i o n w i t h t h e F N v a c c i n e was m o r e p r o n o u n c e d t h a n was t h e r e s p o n s e f o l l o w i n g 17D i m m u n i z a t i o n . T h e h i g h e r f r e q u e n c y o f c o m p l i c a t i o n s f o l l o w i n g t h e u s e o f t h e FN v a c c i n e h a s l e d t o r e p l a c e m e n t a l m o s t e n t i r e l y by t h e 17D v a c c i n e .
A n u m b e r o f m o r e r e c e n t s t u d i e s h a v e s h o w n t h a t w i t h t h e n e w e r HI t e s t s , a n d w i t h m o d i - f i c a t i o n s o f t h e N t e s t , p o s t - v a c c i n a l i m m u n i t y c a n be d e m o n s t r a t e d i n a p r o p o r t i o n a p p r o a c h i n g 1 0 0 % , o f t h o s e who h a v e r e c e i v e d a n a d e q u a t e d o s e o f v i a b l e v a c c i n e . L o b o ( 1 9 5 8 ) p o i n t s o u t , i n c o n n e x i o n w i t h t h e u s e o f t h e HI t e s t , t h e i m p o r t a n c e o f u s i n g a h a e m a g g l u t i n a t i n g a n t i g e n p r e p a r e d f r o m t h e 17D s t r a i n i t s e l f . A v e r y s i g n i f i c a n t l y h i g h e r p r o p o r t i o n o f p o s i t i v e r e a c t o r s w e r e t h u s d e t e c t e d , a s c o n t r a s t e d t o t h e t e s t s r u n i n p a r a l l e l u s i n g a n a n t i g e n p r e p a r e d f r o m t h e J S S s t r a i n o f y e l l o w f e v e r . T h i s i m p o r t a n t o b s e r v a t i o n h a s b e e n r e p e a t e d l y c o n f i r m e d . U s i n g t h e 17D h a e m a g g l u t i n i n , a v e r y c l o s e c o r r e s p o n d e n c e b e t w e e n HI a n d N t e s t c a n be a c h i e v e d . T h e i l e r r e p e a t e d l y o b s e r v e d , i n a n u m b e r o f s t u d i e s o f i m m u n i z e d i n d i v i d u a l s , a p r o l o n g a t i o n o f t h e a v e r a g e s u r v i v a l t i m e o f m i c e u s e d i n t h e c o n v e n t i o n a l i n t r a c e r e b r a l
i n o c u l a t i o n o f a d u l t m i c e t e s t , w h e n r e s u l t s a s j u d g e d by m o u s e m o r t a l i t y m i g h t b e c o n s i d e r e d e q u i v o c a l . He d e v e l o p e d a t e s t u s i n g a s v i r u s s o u r c e t h e A s i b i s t r a i n o f y e l l o w f e v e r v i r u s i n m o n k e y s e r u m , a n d a s t e s t a n i m a l t h e i n f a n t m o u s e i n o c u l a t e d i n t r a p e r i t o n e a l l y . W i t h t h i s t e s t c o n v e r s i o n r a t e s a p p r o a c h i n g 1 0 0 % a r e a c h i e v e d , w i t h c l o s e c o r r e s p o n d e n c e a l s o w i t h H I t e s t s . I n c i d e n t a l l y , t h i s t e s t i s a v e r y s e n s i t i v e o n e f o r d e t e c t i n g h e t e r o t y p i c g r o u p B . . ., a n t i b o d y a l s o .
T h e p r o b l e m o f t h e o c c a s i o n a l i n d i v i d u a l i n whom n o d e t e c t a b l e a n t i b o d y r e s p o n s e
d e v e l o p s r e m a i n s . W i t h t h e i m p o s s i b i l i t y o f e x a m i n a t i o n by a c h a l l e n g e w i t h v i r u l e n t v i r u s , i t i s l i k e l y t o r e m a i n u n a n s w e r e d . W h e t h e r p r e - e x i s t i n g a n t i b o d y t o ( c e r t a i n ) o t h e r v i r u s e s o f g r o u p B i s a f a c t o r w h i c h may b l o c k i n f e c t i o n w i t h a n d m u l t i p l i c a t i o n o f t h e v a c c i n e v i r u s i s c o n j e c t u r a l .
P r o t e c t i o n a f f o r d e d b y y e l l o w f e v e r i m m u n i z a t i o n i s c e r t a i n l y l o n g - l a s t i n g , p o s s i b l y
e f f e c t i v e f o r t h e l i f e s p a n o f t h e i n d i v i d u a l . G r o o t e t a l . ( 1 9 6 2 ) f o u n d N a n d H I a n t i b o d i e s i n a h i g h p r o p o r t i o n o f i n d i v i d u a l s l i v i n g i n a r e g i o n i n B r a z i l w h e r e n a t u r a l l y o c c u r r i n g d i s e a s e h a s n e v e r b e e n r e c o g n i z e d , v a c c i n a t e d 17 y e a r s e a r l i e r . I n t h e HI t e s t s , t h e y a l s o
f o u n d t h e 17D h a e m a g g l u t i n i n g a v e r e s u l t s m o r e c l o s e l y c o r r e s p o n d i n g t o N t e s t r e s u l t s t h a n d i d h a e m a g g l u t i n i n s p r e p a r e d f r o m t w o o t h e r Y F s t r a i n s .
VIR/yF/71.16 page 3 I t has been shown t h a t v a c c i n a t i o n w i t h 17D v a c c i n e can i n d u c e a s e r o l o g i c a l r e s p o n s e t o a range o f g r o u p B a n t i g e n s , i n i n d i v u d u a l s w i t h p r e - e x i s t i n g g r o u p B a n t i b o d i e s ,
w h e r e a s t h e r e s p o n s e i n g r o u p B n e g a t i v e s i s much n a r r o w e r i n r a n g e , e s s e n t i a l l y l i m i t e d t o YF. Wisseman e t a l . ( 1 9 6 2 ) s t u d i e d t h e N r e s p o n s e i n J a p a n e s e who had had p r i o r JE i n f e c t i o n and showed a b r o a d e n e d r e s p o n s e t o s e v e r a l o t h e r g r o u p B v i r u s e s .
Pond e t a l , ( 1 9 6 7 ) c a r r i e d o u t s i m i l a r s t u d i e s i n i n d i v i d u a l s w i t h p a s t h i s t o r y o f SLE o r dengue, h i s t o r y b e i n g s u p p o r t e d by s e r o l o g i c a l f i n d i n g s . T h e s e s t u d i e s were l i m i t e d t o HI and CF, and t h e y showed b r o a d h e t e r o t y p i c HI r e s p o n s e s i n t h e p r i o r g r o u p B immunes, w i t h p a r a l l e l f i n d i n g s w i t h CF a l t h o u g h a t a l o w e r l e v e l and more v a r i a b l e . They remark t h a t
"YF v a c c i n a t i o n i s a p o t e n t t o o l t o r e c a l l p a s t e l e v a t e d HI t i t r e s o f SLE and dengue a n t i - b o d i e s f o r e p i d e m i o l o g i c p u r p o s e s i n o r d e r t o d e t e c t p o p u l a t i o n s i n w h i c h o u t b r e a k s o f g r o u p B a r b o v i r u s i n f e c t i o n s have p r e v i o u s l y o c c u r r e d and may r e c u r " .
Monath ( 1 9 7 0 ) c a r r i e d o u t d e t a i l e d N t e s t s t u d i e s o f t h e i m m u n o g l o b u l i n s a p p e a r i n g f o l l o w i n g 17D i m m u n i z a t i o n . IgM a n t i b o d i e s were f i r s t d e t e c t e d on day e i g h t o r n i n e , r o s e t o h i g h t i t r e s between day 14 and 17 and t e n d e d t o d e c l i n e g r a d u a l l y t h e r e a f t e r . However, s i g n i f i c a n t amounts were d e t e c t a b l e as l o n g as 82 d a y s f o l l o w i n g p r i m a r y i m m u n i z a t i o n .
IgG a n t i b o d i e s a p p e a r e d between 10 and 17 d a y s a f t e r i m m u n i z a t i o n , t e n d e d t o r e m a i n s t a b l e o r t o r i s e s l i g h t l y t h e r e a f t e r , and d i d n o t s u r p a s s IgM t i t r e s . B o t h IgM and IgG a n t i b o d i e s had a h i g h d e g r e e o f s p e c i f i c i t y f o r c e r t a i n s t r a i n s o f YF. Serum N t i t r e s were h i g h e r f o r FN o r 17D t h a n f o r A s i b i o r Dakar 1279. The a n t i b o d i e s were a l s o h i g h l y s p e c i f i c when compared w i t h s e v e r a l h e t e r o l o g o u s g r o u p B v i r u s e s . Monath r e m a r k s t h a t t h e p r o l o n g e d s y n t h e s i s o f IgM a n t i b o d y s u g g e s t s a p e r s i s t e n c e o f a n t i g e n i c s t i m u l a t i o n .
Wheelock e t a l . (1969) have d e m o n s t r a t e d t h a t 17D v i r u s i n f e c t s and m u l t i p l i e s i n u n s t i m u l a t e d human monocyte c u l t u r e s and i n human l y m p h o c y t e c u l t u r e s s t i m u l a t e d t o b l a s t d e v e l o p m e n t by p h y t o h a e m a g g l u t i n i n . U n s t i m u l a t e d m o n o c y t e s and l y m p h o c y t e s e x p o s e d t o 17D p r o d u c e d i n t e r f e r o n . In f u r t h e r s t u d i e s Wheelock e t a l . (1970) have d e m o n s t r a t e d t h a t i n i n d i v i d u a l s v a c c i n a t e d w i t h 17D, t h e i r p e r i p h e r a l l y m p h o c y t e s , s t i m u l a t e d by p h y t o h a e m a g g l u - t i n i n , l o s e t h e i r a b i l i t y t o s u p p o r t g r o w t h o f 17D between s e v e n and 14 d a y s f o l l o w i n g
v a c c i n a t i o n but r e g a i n t h i s c a p a c i t y by t h e t w e n t y - f i f t h day p o s t - v a c c i n a t i o n . I n one d o n o r , however, t h e r e f r a c t o r y s t a t e p e r s i s t e d f o r 76 d a y s , but had d i s a p p e a r e d by t h e two h u n d r e d and f o r t y - e i g h t h day a f t e r v a c c i n a t i o n . Wheelock e t a l . (1969) s u g g e s t t h a t " f o l l o w i n g i m m u n i z a t i o n , l y m p h o c y t e s i n t h e l y m p h o r e t i c u l a r t i s s u e s o f immune i n d i v i d u a l s may c o n t a i n 17D v i r u s w h i c h r e m a i n s i n a s l o w l y r e p l i c a t i n g o r n o n - r e p l i c a t i n g l a t e n t s t a t e f o r p r o l o n g e d p e r i o d s o f t i m e " .
V I R / Y F / 7 1 . 1 6
