Molecular epidemiology of hepatitis B virus in Latin America

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Journal of Chmcal V~rology 34 Suppl 2 (2005) $8 S13 www elsevier com locate jcv

Molecular epidemiology of hepatitis B virus in Latin America Rodolfo H. Campos*, Viviana A. Mbayed, Flavia G. Pineiro y Leone Cdte& a de l't~olog[a, Facultad de Fat macta y Btoqu[mtc a, Untc'e~ sMad de Buenos Aries, lun/n 956 4° ptso, C l l l 3AAB, Ctudad de Buenos Aries, A~ gentma

Abstract

Hepatitis B virus (HBV) is an etiological agent of acute and chromc hver disease existing throughout the world The htgh genetic vanablhty o f HBV is reflected by mght genotypes (A to H), each one with a paxtlcular geographical prevalence The global pattern o f HBV genotypes is assocmted with the &stnbutlon o f human populations among the different continents and may reflect the patterns o f human migrations Genotypes F and H axe considered m&genous to Latin America The most prevalent genetic group of Central and South America, genotype E is sub&wded into two subtypes and five clusters assocmted with defined geographic areas Genotype H has been described m Mexico and Central America This pattern prowdes a tool to reconstruct the mltml mmngratlon o f ancestral Amermdmxls from Asm and thmr further spread through Central and South America Other HBV genotypes tbund m different Latin American couxltnes may reflect migration fi'om other geographical areas into the region Genotypes A and D are the s~gnatuxe of the European colomzatlon that started m the stxteenth century, including slave trade fi'om Afi'~ca Genotypes B and C m&cate the axnval of people from Southeast Asm The impact o f HBV genotypes on the natural course of HBV mfect~on and response to treatment has been studmd recently and controversml results have been obtained The majority o f the current reformation concerns w~th genotypes B and C In contrast, very few data are available on the Latin Amencax~ HBV genotypes F and H It has been reported that hver t;mluxe and death may be more fi'equent m patmnts infected w~th genotype F More studms are needed to assess the assocmt~on between HBV genotypes and clinical course of mfect~on, especmlly m Latin America 'c' 2005 Elsewer B V All rights reserved Kevwotds Hepatitis B virus, Molecular ep~demmlogy, Latin America, L~ver &sease

1. Introduction Hepat~tls B wrus (HBV) ~s an et~olog~cal agent of acute and chromc hver &sease prevalent throughout the world. More than 350 mflhon people are chromc carriers of the wrus. HBV mfect~on is an ~mportant cause of chronic hepatms, hver clrrhos~s, and hepatocellular carcinoma (Lee, 1997, Zuckerman and Zuckerman, 2000). The wrus ~s a member of the HepadnavtrMae family which includes wruses recovered from a vanety of ammal species, the awan wruses being the most &vergent. Mammahan wruses compnse those infecting rodents, humans, and other primates (Alba et al., 2003, Starkman et al., 2003). HBV contains a pamally double-stranded DNA genome of approximately 3200 base pmrs. HBV rephcates wa an RNA mtermedmte ant>genome sequence, encoding a * Corresponding author Tel +54 11 49648264, fax +54 11 45083645 E-marl a&hess rcampos(a,ffyb uba ar (R H Campos)

1590-8658 $

see front matter ,c, 2005 Flsevler B V All rights reserved

potentmlly error-prone polymerase enzyme without proofreading act~wty. The error frequencms are similar to those of retrowruses and other RNA wruses. The HBV genome codes for proteins through four open and pamally overlapping reading frames. Tins unusual genom~c structure ~s important to compress a large amount of mformatmn into short sequences but ~mphes a constrained evolutmn for the wrus. Th~s constrain can be reflected on the calculated rate of subst~tutmn, 10 5 per s~te per year, slower than the rate &splayed by the retrowruses of around 10 3 per s~te per year (M~zokam~ et al., 1997, Jenkins et al., 2002).

2. HBV genotypes and subtypes The genetic vanabflW of HBV ~s reflected by different genotypes. Based on complete genome sequences HBV has been classified into mght genotypes, A to H, that are related to thmr geographmal ongm (Norder et al., 1994, Stuyver et al., 2000, Arauz-Rmz et al., 2002) (F~g. 1). The worldwide HBV genotype prevalence ~s a result of the

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F]g 1 (A) Mm]mum evolut]on-phylogenet]c tree of hepat]t]s B v]rus (HBV) complete genomes (genotypes A H) obtained w]th the PAUP software vers]on 4 0bl0 (Swofford, 2002) The evolut]onary model and parameters used (TVM + I + G) were est]mated by the MODEL TEST program (Posada and Crandall, 1998) The numbers at each node correspond to bootstrap values obtained w]th 1000 rephcates, using the same model All stratus from GenBank are labeled w]th the]r corresponding database access]on number followed by an rod]cat]on m bold of genotype Woolly monkey (WM) HBV strata NC001896 was used as outgroup Horizontal branch lengths are drawn to scale (B) Enlarged v]ew of HBV genotype F phylogenet]c topology Each GenBank access]on number ]s followed by an rod]cat]on m brackets of the country of ongm Roman numbers md]cate clusters w]thm each subtype, F1 and F2 (m bold) The numbers at the nodes correspond to bootstrap values

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R H Cat~pos et a l / Ioutnal o/'Chntcal l'ttolog~' 34 Suppl 2 (2005) $8 S13

d~stnbuhon of humans on different continents (Robertson and Margohs, 2002). Genotype A is present m Europe, India, Africa, and North Amenca, genotypes B and C predominate m China, Japan, and Southeast Asia. Genotype D is widespread, predominating m the Mediterranean area and m the Middle East region, genotype E appears to derive from West Africa (Norder et al., 1993, Kldd-Ljunggren et al., 2002). Genotype G has mainly been found m France, Mexico, and the USA (Stuyver et al., 2000, Sfinchez-Tap~as et al., 2002). Genotype F is found m Central and South Amenca while genotype H has been described m Mexico and Central America (Norder et al., 1993, Arauz-Rmz et al., 1997, 2002). The eight genotypes of HBV can be further subdlwded ~nto subgroups w~th d~stmct ethmc or geographic origin. Genotype A formed two major geographical clusters, the European North Amencan (Ae) and the A f r o ~ s ~ a n (Aa) (Sugauch~ et al., 2004a). Genotype B also represents two subtypes: Ba, prevalent throughout Asia except for Japan, and Bj, mainly found m Japan (Sugauch~ et al., 2004b). Genotype C represents at least two subtypes: C 1 m South East Asia and C2 m Far East Asia (Huy et al., 2004). Recently, a new genotype C variant has been found m Austrahan aborigines (Sugauch~ et al., 2001). W~thin genotype D, a subtype composed entirely by Pacific island stratus has been described (Jazayen et al., 2004). The most prevalent genotype of Central and South America, genotype E is subd~wded ~nto two subtypes, F 1 and F2 (Norder et al., 2003). Based on complete genome sequences from hepatms B e antigen (HBeAg) posmve samples five clusters were descnbed (P~fielro y Leone et al., 2003). Subtype F1 includes two clusters, Ia and Ib, w~th stratus ~solated mainly m Central America (Costa R~ca, E1 Salvador, and N~caragua) and Argentina, respechvely. Subtype F2 includes three clusters w~th stratus found m N~caragua, Venezuela, and Brazil (cluster II), m Panama, Venezuela, and Colombia (cluster III), and m Argentina and Bohwa (cluster IV). Small S gene analys~s can add to the understanding of the molecular ep~dem~ology of HBV (Norder et al., 1992, 1993, Mbayed et al., 2001). W~th th~s method, an extended descnphon of Latin Amencan genotype F stratus reinforced the above mentioned genotype/ subtype d~stnbuhon and added ~mportant mformahon on Bramhan ( subtype F2 cluster IV) and Peruwan ( subtype F 1 ) wruses (Gomes et al., 2004, Schaefer, 2005). Phylogenehc analys~s of Peruwan sequences available m GenBank indicated that those stratus should be included m cluster Ib.

3. HBV genotype distribution and migration to Latin America HBV genotype d~stnbunon may reflect the different patterns of m~granon to the Americas (Arauz-Rmz et al., 1997, K~dd-Ljunggren et al., 2002). It has been proposed that

autochthonous HBV genotypes entered the continent with the first settlers that came to America from Asia across the Bering Strait and moved down to the south (ArauzRmz et al., 2002 ). The mmal ancestral Amermd~ans entered the New World between 20000 and 15000 years ago. They probably migrated to the south along the coast, since the glacial coalescence prevented access to North America wa an interior route. This allowed a rap~d expansion to Central and South America. A second mlgranon to North and Central America took place around 12 500 years ago, possibly through an interior route (Schurr, 2004). Ewdence from m~tochondnal DNA (mtDNA) hneages suggests the lsolanon of some Amennd~an populanons soon after the mlnal d~spersal of settlers m the Southern part of the continent (Bortohni et al., 2003). Th~s ~solanon could be m~rrored by different geographic locanon of HBV subtype F and clusters. The d~stnbunon of HBV F-subtypes correlates w~th a possible entrance to South America along the eastern (F1, cluster Ib) and western (F2, clusters II, III, and IV) coasts. Where the continent becomes narrower, both paths could have gone closer. As a result, m Argentina a mixture of both subtypes F1 (cluster Ib) and F2 (clusters IV) was found (Fig. 2). Other HBV genotypes are found m different Latin American countries and mainly reflect m~granon from other geographical areas into the region. Genotypes A and D are the s~gnature of the European colomzanon that started m the s~xteenth century including slave trade from Africa (genotype A). Analyses of genotypes B and C indicate later mtroducnon from Southeast Asia (F~g. 2). Genotypes A, B, and D were found m Argentina (Telenta et al., 1997, Franca et al., 2004). Genotypes A, B, C, and D were described m Brazil w~th A and D the most prevalent (Araujo et al., 2004, S~tmk et al., 2004, Rezende et al., 2005). The high prevalence of A and D genotypes differentiates Brazil from the other Latin American countries. Stratus from genotypes B and C were ~solated m Peru (Vasquez et al., 2004, unpubhshed). Genotypes A, H, and G were detected m Mexico while genotypes A and H were found m Nicaragua (Arauz-Rmz et al., 1997, Sfinchez et al., 2002). Genotypes A and D were described m Venezuela, Uruguay, and Costa R~ca (ArauzRmz et al., 1997, Bhtz et al., 1998, Rebaghatn et al., 2000, Gun6rrez et al., 2004). HBV genotype A forms two major geographical clusters, the European North American (Ae) and the Afro As~an (Aa). Until recently, the presence of genotype A m Latin America was thought to be exclusively associated w~th the European reflux (subtype Ae) but a recent study demonstrated the existence of a large African (subtype Aa) component m Brazil explained by slave trade dunng colonial rimes (Araujo et al., 2004). In Argentina, the prevalence of genotype A stratus vanes depending on the geographic locanon. In Buenos Aires they represent more than 28"/,, but m Gualeguay, a small c~ty m the Prownce of Entre Rios founded during the European colomzanon,

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all stratus were found to be genotype A (Mbayed et al., 1998, Ldpez et al., 2002). A very recent analys~s of these prewously pubhshed sequences reveals that they belong to subtype Ae, while recently described sequences from the North East of the country belong to subtype Aa (P~fie~ro y Leone, unpubhshed/. The genetic d~vers~ty of HBV and the geographical d~stnbut~on of ~ts subtypes prowde a tool to reconstruct the evolutionary history of HBV (Norder et al., 2004). The clustering described suggests that a deeper analys~s of HBV evolution associated to geographical ongm should be conducted. However, a large amount of complete genome sequences must be stud~ed to assess such a clustering process.

4. Clinical significance of HBV genotypes The course of HBV mfect~on depends on several factors mvolwng both the wrus and the host. The impact of HBV

genotypes on the natural course of HBV refection and response to treatment has been studied recently. Most of the mformat~on available comes from studies m the endemic area of Asia w~th genotypes B and C predominating. These analyses have been extended to other regions of the world but data from Latin America w~th different molecular ep~dem~ology are scarce. When the natural course of chronic hepatms B was studied, mfect~on w~th genotype A was more related to spontaneous sustained remlss~on and milder d~sease (Sfinchez-Tap~as et al., 2002, Thakur et al., 2002). Patients w~th genotype C mfect~on may develop advanced hver disease more frequently than those w~th genotype B or D (Kao et al., 2000a, Nakayosh~ et al., 2003, Duong et al., 2004). Moreover, associations were described between genotype C mfect~on and hepatocellular carcinoma m China, Ta~wan, and Japan (Kao et al., 2000a, Onto et al., 2001, Chan et al., 2003, Yu et al., 2005). Studies on the prevalence of HBeAg m patients w~th d~fferent genotypes have led to conflicting results. In Japan,

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R H Campos et a l / lomnal o/'Chntcal l'ttolog~' 34 Suppl 2 (2005) $8 S13

~t w a s s h o w n that H B e A g w a s s~gnlficantly m o r e f r e q u e n t m p a h e n t s w i t h g e n o t y p e C m f e c h o n t h a n m t h o s e w~th g e n o t y p e B or D ( O n t o et al., 2 0 0 1 , N a k a y o s h ! et al., 2 0 0 3 , D u o n g et al., 2004). I n add~hon, the rate o f H B e A g s e r o c o n v e r s ~ o n w a s lower m p a h e n t s w~th g e n o t y p e C m f e c h o n t h a n m t h o s e w~th g e n o t y p e B m Japan, C h i n a , a n d Ta~wan ( C h a n et al., 2 0 0 3 , N a k a y o s h ! et al., 2 0 0 3 , K a o et al., 2004). M o r e o v e r , m p a h e n t s f r o m v a r i o u s g e o g r a p h i c a l origins, the p r e v a l e n c e o f ant~-HBe a n t i b o d i e s w a s less f r e q u e n t m m d ~ w d u a l s w~th g e n o t y p e s B a n d C t h a n m t h o s e w i t h D m f e c h o n s ( K ~ d d - L j u n g g r e n et al., 2004). O n the o t h e r h a n d , n o s~gmficant d~fferences w e r e f o u n d m the p r e v a l e n c e o f H B e A g m p a h e n t s w i t h g e n o t y p e A or D m f e c h o n a n d m the rate o f H B e A g / a n t ~ - H b e a n t i b o d y seroconvers~on m the g r o u p s o f p a h e n t s w~th g e n o t y p e s A, D or F ( S f i n c h e z - T a p m s et al., 2 0 0 2 , T a n a k a et al., 2004). A subanalys~s o f p a h e n t s w~th g e n o t y p e A m f e c h o n s h o w e d that t h e p r e v a l e n c e o f H B e A g m a y b e l o w e r m p a h e n t s w~th s u b t y p e A a t h a n m t h o s e w i t h s u b t y p e A e ( T a n a k a et al., 2004). T h e c o r r e l a h o n b e t w e e n H B V g e n o t y p e a n d r e s p o n s e to ant~wral t h e r a p y h a s not yet b e e n d e f i n e d clearly. S o m e authors suggest a better response of genotype B mfechon to ~nterferon or l a m ~ v u d m e t r e a t m e n t w h e n c o m p a r e d to g e n o t y p e C m f e c h o n (Kao et al., 2 0 0 0 a , b , Wa~ et al., 2002). O t h e r s d~d not find s u c h a d~fference (Suzuk~ et al., 2 0 0 3 , Y u e n et al., 2003). D a t a m i g h t b e e v e n m o r e c o n f l i c t i n g for o t h e r g e n o t y p e s , a n d d~fferent m u t a h o n a l p a t t e r n s o f l a m l v u d m e r e s i s t a n c e a s s o c m t e d w~th H B V g e n o t y p e w e r e r e p o r t e d r e c e n t l y (Z/511ner et al., 2004). Very few data are available a b o u t t h e m a j o r L a t i n A m e r i c a n H B V g e n o t y p e s . A r e c e n t l y p u b h s h e d analys~s o f a s m a l l g r o u p o f S p a m s h p a h e n t s i n f e c t e d w~th g e n o t y p e F s u g g e s t e d that this g e n o t y p e m a y b e a s s o c i a t e d w i t h m o r e f r e q u e n t h v e r failure a n d d e a t h (Sfinchez-Tap~as et al., 2002). M o r e studies are t h u s n e e d e d to assess p o s s i b l e c o r r e l a h o n s b e t w e e n the m a j o r L a t i n A m e r i c a n H B V g e n o t y p e s / s u b t y p e s a n d b o t h the c h n l c a l c o u r s e o f m f e c h o n a n d the r e s p o n s e to a n t ~ - H B V therapy.

Acknowledgements T h i s w o r k w a s s u p p o r t e d b y g r a n t s f r o m the U m v e r s l d a d de B u e n o s A i r e s ( S E C y T - U B A , B 0 3 6 ) , C o n s e j o Nac~onal de I n v e s h g a c ~ o n e s C~entificas y T 6 c m c a s ( C O N I C E T , P I D 723), a n d Agenc~a Nac~onal de P r o m o c ~ d n C~entifica y Tecnoldglca (ANPCyT, PICT 2000 05-08355).

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