R e v i s t a d a S o c i e d a d e B r a s i l e i r a d e M e d i c i n a T r o p i c a l 2 7 ( l ) : l - 4 , j a n - m a r , 1 9 9 4
A R T IG O S
R E S P IR A T O R Y S Y N C Y T IA L V IR U S (R S V ) B R O N C H IO L IT IS : C O M P A R A T I V E S T U D Y O F R S V G R O U P S A A N D B
I N F E C T E D C H IL D R E N
S e lir M . S tr a lio tto , B e n ja m in R o itm a n , J o â o B . L im a , G ilb e r to B . F isc h e r a n d M a r ild a M . S iq u eira
T h e g r o u p i n g c h a r a c t e r i s t i c s o f 2 9 r e s p i r a t o r y s y n c i t i a l v i r u s (R S V ) p r e s e n t in n a s o p h a r y n g e a l c e l l s c o l l e c t e d f r o m h o s p i t a l i z e d c h i l d r e n w it h b r o n c h i o l i t i s d u r i n g t h e 1 9 9 0 R S V s e a s o n in P o r t o A l e g r e , R S , w e r e a n a l y s e d . T w e n t y - t w o w e r e g r o u p e d a s b e l o n g i n g t o g r o u p A a n d 7 to g r o u p B . C y a n o s i s , o x i g e n t h e r a p y , c o u g h , l e n g h t o f h o s p i t a l i z a t i o n a n d a t e l e c t a s i s w e r e o b s e r v e d t o b e m o r e f r e q u e n t l y f o u n d w i t h i n g r o u p B i n f e c t e d c h i l d r e n . O th e r c l i n i c a l s i g n s a n d s y m p t o m s w e r e s i m i l a r l y f o u n d in b o t h g r o u p s .
K e y - w o r d s : R e s p i r a t o r y s y n c y t i a l v i r u s . B r o n c h i o l i t i s . R S V g r o u p s A a n d B .
Respiratory syncytial virus (RSV) is the major cause o f low er respiratory tract infections in infants and young children in the w orld12. It is the main cause o f bronchiolitis and pneum onia in children under 6 m onths o f age7. Annual epidemics are signalled by an increase in the num ber o f children adm itted to hospitals due to bronchiolitis and pneumonia. Two groups o f RSV, A and B, had recently been described according to their reactivity w ith a panel o f monoclonal antibodies (MAbs)210. Epidem iological studies have demonstrated that these 2 groups can cocirculate in annual epidemics in different regions o f the w orld1 5 9 14 18 20.
The recent identification o f 2 groups o f RSV has led to speculation that these groups may affect severity and recurrence. Studies pertinent to the clinical im portance o f RSV groups A and B provide limited inform ation and conflicting results5 1315 21.
In this report, clinical aspects o f RSV groups A and B w ere analysed in children under 1 year o f age w ith bronchiolitis in which RSV was detected in clinical samples by im munofluorescence with a polyclonal RSV antiserum.
Instituto de Pesquisas Biológicas, Hospital de Clínicas de Porto A legre, Hospital das C rianças Santo Antônio, Porto Alegre, RS e D epartam ento de V irologia, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
A d d r e s s to : D ra. M arilda M . Siqueira. Depto. de Virologia/ F IO C R U Z . C P : 92 6 , 21045-900 Rio de Janeiro, R J, Brasil; T el: (021) 598-4360, Fax: (021) 270-6397.
R ecebido para publicação em 2 9 /0 9 /9 2 .
M ATERIALS AND M ETHODS
S p e cim en s e x a m in e d . This study included 128 children under 1 year o f age w ith clinical diagnosis o f bronchiolitis, hospitalized at two paediatric hospitals in Porto Alegre, RS, during the m o n th s o f Ju n e , Ju ly and A u g u s t, 1990. Nasopharyngeal secretions (NFS) w ere collected in the first seven days o f illness by suction through a nasal catheter according to G ardner and M cQ uillin3 and sent immediately at 4°C to the laboratory. The NPS were processed for rapid virus diagnosis by indirect im munofluorescence (IFAT) as described elsewhere16, using a guinea-pig anti-RSV serum (FIOCRUZ, Brazil) and a fluorescein-conjugated rabbit antiguinea-pig serum (Sigma, USA). All samples were also tested for adenovirus by the IF AT. Duplicate slides w ere prepared and stored at -70°C, when the specimen was available in sufficient amounts.
These slides were sent to FIO C R U Z, RJ, for grouping by indirect im munofluorescence staining with monoclonal antibodies specific for group A (92-1 lc) and group B (102-10b) (kindly supllied by Dr. L .J. Anderson, CDC, USA). T he dilution of MAbs and antim ouse-FITC conjugated (Cappel, USA) were standardized as previously described17. V a r ia b le s. Clinical observations included the presence o f wheezing, fever, cyanosis, apnea at any time during hospitalization, the use o f mechanical ventilation, lenght o f hospital days and requerim ent for intensive care. In the counting o f hospital days,
S t r a l i o t í o S M , R o i t m a n B , L i m a J B , F i s c h e r G B , S i q u e i r a M M . R e s p i r a t o r y s y n c y t i a ! v i r u s (R S V ) b r o n c h i o l i t i s : c o m p a r a t i v e s t u d y o f R S V g r o u p s A a n d B i n f e c t e d c h i l d r e n . R e v i s t a d a S o c i e d a d e B r a s i l e i r a d e M e d i c i n a T r o p i c a l 2 7 : 1 - 4 , j a n - m a r , 1 9 9 4 .
the day o f adm ission was counted as a full day. C hest X -ray observation included atelectasis, consolidation and hyperinflation.
S ta tistica l analysis. The statistics analysis was m ade using chi square test.
RESULTS
From June to August, 1990, 128 children were hospitalized with clinical diagnosis o f bronchiolitis. M ost o f the children were males (78.6 %) aged 3-6 months. Clinical data more frequently found were wheezing, cough, high respiratory rate and cyanosis. X -ra y fin d in g s f r e q u e n tly o b s e rv e d w ere hyperinflation and consolidation. The lenght of hospitalization o f most the cases were less than seven days, and 9 children required intensive care.
F rom the 42 RSV positive cases, 29 were characterized in group A and group B. Twenty-two belonged to group A and 7 to group B. Table 1 shows the com parison o f clinical and radiologic findings betw een th e two groups. C yanosis, atelectasis, and cough were frequent in group B infected children. Other signs and symptoms were sim ilarly found in both groups. Almost all children received large doses o f antibiotics and bronchodilator treatm ent but oxigen therapy was used mainly in g ro u p B (T a b le 2 ). T h e m ean le n g h t o f hospitalization from group A infected children was shorter than in group B infected ones. Five patients
T a b l e 1 - C o m p a r i s o n o f R S V g r o u p s A a n d B in f e c t io n in r e l a t i o n t o c l i n i c a l a n d X - r a y f i n d i n g s in c h i l d r e n w i t h b r o n c h i o l i t i s .
g ro u p A g r o u p B ( n = 2 2 ) (n = 7 )
Clinical findings
h ig h r e s p ir a to r y ra te 1 4 5
w h e e z in g 19 6
fe v e r 15 4
c o u g h 1 7 7
c y a n o s is 4 3
c r e p it a tio n s 13 3
X-ray findings
h y p e r in f la tio n 1 8 6
a t e le c t a s is 5 3
c o n s o lid a t io n 1 6 5
T a b le 2 - C o m p a r i s o n o f t h e r a p e u t i c m e a s u r e s a n d d a y s o f h o s p i t a l i z a t i o n b e t w e e n R S V g r o u p s A a n d B i n f e c t e d c h i l d r e n .
g r o u p A
(n=22)
g r o u p B
(n —7 )
Therapeutic measures
a n tib io tic 14 4
o x ig e n 1 0 6
m e c h a n ic a l v en tila tio n 2 o b ro n ch o d ila to r b y n e b u liz e r 18 4 b r o n c h o d ila to r IV 13 5 b lo o d tr a n s fu sio n 3 2
Days of hospitalization
< 8 d a y s 12 2
8 - 1 4 d a y s 5 2
> 1 4 d a y s 3 3
received blood transfusion because they had anaemia. The statistical analysis was im paired by the small size o f group B. In spite o f this, the more objective data was tested using chi square test. No significant difference was found between group A and group B; there is no material difference for the three types o f X-ray findings between the two groups (without Yates correction even). The test result (X2 = 0.056; p > 0.1) is equally valid for the other data, the clinical findings including. For example, if the difference between A/B groups on less than 8 days of hospitalization (Table 2) was significant, this result depends on the more objective data - the X-ray findings.
DISCUSSION
The results described in the present paper are similar to several others from different countries that showed the simultaneous circulation o f the two groups o f RSV w ithin the same com m unity during the same RSV season. These studies have also demonstrated that the pattern o f isolation o f two RSV groups can vary from year to y ear1 5 9 18. RSV groups A and B appear to differ prim arily in the largest surface glycoprotein, th eG p ro tein , whereas the other major surface glycoprotein, the F or fusion protein, is relatively well conserved6. For this reason, in the present w ork it w as used
S tra lio tto S M , R o itm a n B , L im a J B , F isch er GB, S iq u eira M M . R esp ira to ry sy n c y tia l viru s (RSV ) b r o n c h io litis: c o m p a ra tiv e s tu d y o f R S V g r o u p s A a n d B in fe c ted children. R e v ista d a S o c ied a d e B ra sile ira d e M e d ic in a T ro p ic a l 2 7 :1 -4 , ja n - m a r , 1994.
monoclonal antibodies specific for group A (92- 1 lc ) and B (102-10b) w hich recognize epitopes on the fusion protein o f the virus2.
Some reports suggest that antigenic differences between the two m ajor groups o f RSV isolates may be im portant in the clinical and epidemiologic features o f RSV disease. Previous reports found conflicting results in analysing epidem iologic features and comparing lower and upper-respiratory - tract infections w ithout presenting clinical variables. In a study o f Hendry et al5, there w ere no major differences in age, sex or frequency o f nosocomially acquired RSV between infants infected with groups A and B, between one outbreak and that followed it. as well as into each outbreak. W aris21 found that yearly hospitalization rate was not demonstrably dependent on group virulence and that both groups o f RSV are epidem iologically equally important. In Rio de Janeiro, a retrospective study analysis o f children infected with RSV, showed a predominance o f group A in some years18 but the rate o f infections caused by A and B strains was the same both in hospitalized children and in less ill outpatient children (M .M . Siqueira, data not published). Other reports showed a predominance o f group A infection among hospitalized children9 and in those who required intensive care4.
In this study, we analysed the A and B groups o f children with brochiolitis. The clinical signs that indicates severity in acute bronchiolitis are cyanosis, c r e p ita tio n s an d o x y g e n s a tu ra tio n ( S a 0 2) measurem ents11. Cyanosis was present in three children infected w ith RSV group B, but the presence o f crepitations was not too different in both groups. S a 0 2 measurement was not available in the present study. Intensive care as measured by oxygen therapy and mechanical ventilation as well as the lenght o f hospitalization and atelectasis w ere more frequently in those children infected w ith group B RS V. Group B infection was correlated w ith more severity in som e clinical variables, but the num ber o f cases studied was few to establish difference in severity between the 2 groups.
Until n o w , few reports compared a great vari ety o f b ac k g ro u n d featu res, clin ical signs and sym ptoms8 13 15 19. Data from larger numbers o f children suggested that group A infection was more severe. Salomon et al15 in 116 typed samples (A, n = 23; B, n = 93) from children under 2 years o f age found that the presence o f atelectasis and
wheezing w ere significantly m ore common among the group A infected children, suggesting a more severe disease. A lthought Russi et a l13 observed higher respiratory rates in group A infections, the num ber o f children under 1 year o f age was few (A, n = 1 4 ;B ,n = 11) and they could not established a clear-cut difference in virulence.
For some studies cited, including the present one, the frequencies o f RSV groups A and B were studied only at the hospital and w ere not com pared w ith infection in the com m unity. The conflicting findings from different investigators about severity and virulence o f group A and B m ight reflect the use o f different methods other than the absence or presence o f a correlation. The controversial reports on the virulence o f RSV groups point to the need to establish accepted standards to evaluate severity13. Analysis o f the clinical signs and sym ptoms in hospitalized and outpatient children are in progress; further investigations o f the clinical relevance o f RSV groups are necessary.
A CK N O W LED G EM EN T
W e would like to express our sincere thanks to Dr. J.P . Nascimento, Instituto Oswaldo Cruz, for her helpful suggestions and the review o f the m anuscriptandtoD r. A. M orgado, Escola Nacional de Saúde Pública, for the statistical analysis.
RESUM O
E stu dos recentes d e am o stra s d o vírus respiratório s in c ic ia l (V R S ) u s a n d o a n tic o r p o s m o n o c lo n a is distiguiram d uas variantes antigênicas, d esig n a d a s com o g ru p o s A e B. E stes g ru p o s fo r a m estu d a d o s em 29 s e c r e ç õ e s d e n a s o fa r in g e p o s itiv a s p a r a o VRS, p ro ven ien tes d e cria nças hospitalizadas co m bronquio lite du rante surto d e virose p o r VRS, em P o rto A le g re, em 1990. D estas, 22 fo r a m g ru p a d a s co m o p erte n c e n te s ao grupo A e 7 ao g rupo B. A lg u n s ach a d o s clínicos com o cianose, tosse, uso d e o xig ên io e d ia s d e h o sp italização fo r a m m ais fre q ü e n te m e n te o b serva d o s em cria n ça s infectadas coin o g ru p o B d o VRS. O utros sin a is e sin tom as clín icos fo r a m sim ila rm en te e n co n tra d o s n o s 2 grupos.
P a la v ra s-c h a v e s: V írus r e s p ir a tó r io sin c ic ia l. Bronquio lite. G rupos A e B d e VRS.
S tra lio tto S M , R o itm a n B , L im a J B , F ischer G B, S iq u eira M M . R esp ira to ry sy n c y tia l viru s (RSV ) b ro n c h io litis: co m p a ra tiv e s tu d y o f R S V g r o u p s A a n d B in fe cted ch ild ren . R e v ista d a S o cied a d e B ra sile ira d e M ed ic in a T ro p ica l 2 7 :1 -4 , ja n -m a r , 1994.
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