An Overview of Arbovirology in Brazil and Neighbouring Countries
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An overview of Arbovirology in Brazil and neighbouring countries. Edited by: Amélia P. A. Travassos da Rosa Pedro F. C. Vasconcelos Jorge F. S. Travassos da Rosa BELÉM INSTITUTO EVANDRO CHAGAS 1998 Part 1: Classification, systematics and molecular biology "The viroses, instead of being single-minded agents of disease and death, now begin to look more like mobile genes. Evolution is still an infinitely long and tedious biologic game, with only lhe winners staying at lhe table, but lhe rules are beginning to look moreflexible. Welive inadancingmatrix ofviruses,' theydart, ratherlike bees,from organism to organism, from plant to insect to mammal to me and back again, and into lhe sea, tugging along pieces of this genome, strings of genesfrom that, transplanting grafts of DNA, passing around heredity as thought at a great party. Theymay be lhe mechanismfor keeping new, mutant kinds ofDNA in widest circulation among us./fthis is true, lhe oddvirus disease, on which we mustfocus so much of our attention in medicine, may be looked on as an accident, somethimg dropped. " Lewis Thomas 18 INTRODUCTION isolated in the Evandro Chagas Institute, including some described for the first time in the Brazilian Arnazon region, their known hosts, and their pathology for mano Jorge F. S. TRAVASSOSDA ROSAl Amélia P.A. TRAVASSOSDA ROSAl Pedro F. C. VASCONCELOSl Francisco P. PINHEffiO2 Sueli G. RODRIGUESl Elizabeth S. TRAVASSOSDA ROSAl Leonidas B. DIAS3 Ana C. R. CRUZl 1. Centro Colaboradorde Investigaçãoe Adestramentoem Arboviroses da OrganizaçãoMundial da Saúde, Serviçode Arbovirus, Instituto EvandroChagas, Fundação Nacional de Saúde,Ministério da Saúde.Av. Almirante Barroso,492, 66090-000,Cx. Postal1128, Belém, Pará, Brazil. 2. PanAmericanHealth Organization, 525 Twenty-thirdStreet, Washington, DC, 20037-2895,USA.3. Laboratório de PatologiaClínica Dr. PauloAzevedo, Belém, Pará, Brazil. 19 Arboviruses INTRODUCTION Arbovirus studies conducted in many areas of the Brazilian Amazon region over the past 40 years revealed the presence of a large number of agents. Between November 1954 and Oecember 1994, almost 10,000 isolations ofat least 186 different virus types have beenmade. Ofthese arboviruses, 157 were first isolated in Brazil, and 84 ofthem have beenconfirmed to be new to the world. Thirty four ofthese serotypes are known to be pathogenie to mau, causing rever, rever with rash, hemorrhagic diseaseand encephalitis. Twenty-nine of them have been isolated from natural infections and three from acquired laboratory infections. Ofthe three arboviruses responsible for encephalitis (EEE, WEE & SLE) only SLE has beenisolated twice from persons in the region, with no signs of encephalitis. Antibodies to these agents have been found at low rates in the majority ofthe towns in Para State (Travassos da Rosa ~., 1982; Pinheiro ~., 1986; Vasconcelos~., 1991). It is important to emphasize that the majority of arboviruses causea mild diseasewith a benign evolution, without death or incapacity. A few exception have beenassociated with a fatal outcome. In this latter group are included yellow rever and Xingu viroses. Yellow rever virus has been isolated in sporadic or ongoing outbreaks. Xingu virus was isolated from a single fatal case in whom it was associate with hepatitis B vírus infection. Arboviruses with indetermined pathogenicity to mau constitute the majority of the arboviruses in Amazon region. It is difficult to appraise the importance of such agents as human pathogens. The arboviruses found in the Amazon are distributed in 20 serological groups containing 134 different serotypes (Travassos da Rosa ~., 1986). The remaining viroses are ungrouped. The Changuinola group, with 42 serotypes, is the largest in number, followed by the Phlebotomus rever group, with 18 types, of which three are pathogenic to mano The remaining groups, A, B, C, Bunyamwera, Guama, Capim, California, Anopheles A, Simbu, Turlock, Gamboa, VSV, Timbo, Mossuril, Kwata, Hart Park, Tacaribe and Corriparta, contain eight or fewer agents. Two groups -C and Guama -were initially formed ofviruses exclusively from the Brazilian Amazon, but later, arboviruses from other regions of the Americas were discovered and incorporated into these groups. Based on their physic-chemical properties, the arboviruses of the Brazilian Amazon are distributed into tive families: Togaviridae, Flaviviridae, Bunyaviridae, Reoviridae and Rhabdoviridae. Agents are algo recognised in the families Arenaviridae, Poxviridae, Herpesviridae, Paramyxoviridae and Coronaviridae. In the following pages, these arboviruses are listed according to their systematic and antigenic position, and lhe principal sources from which virus has beenobtained: humanfebrile cases,sentinel animaIs, forest arthropods and wild animaIs. TOGAVIRIDAE,Alphavirus (former group A arboviruses) At present, eight viroses have beenassigned to the genusAlphavirus (Table I). They include the previously unknown Aura (AURA), Una (UNA), Mucambo (MUC) and Pixuna (PIX) viroses, as well as, EEE and WEE isolated for the first time in USA, and Mayaro (MAY) originally isolated in Trinidad, Port of Spain. AURA and UNA have beenisolated in Brazilian Amazonia only from mosquitoes chiefly Aedes serratus and Psorophora ferox, respectively. MUC virus has beenisolated from alI four types of source (man, wild and sentinel animaIs, and arthropods). PIX virus has been obtained twice from mosquitoes (Anopheles nimbus and Trichoprosopon digitatum) and once from a wild rodent (Proechimys guyannensis). This virus was algo associated with no fatal laboratory acquired infection. MAY virus causes a febrile exanthematic disease, associated with persistent joint paio (Pinheiro ~, 1981), and the members of maintenance cycle are Haemagogus mosquitoes, primates and probably birds (Pinheiro, 1982). EEE virus has been isolated from mosquitoes (Culex and Aedes taeniorhynchus), mammals, birds as well from sentinel chicken, mouse and monkey, while WEE has beenisolated from mosquitoes(Culex andAedesfulvus), birds and once from sentinel mouse (Hervé ~., 1986). Triniti virus may be a member ofthe family Togaviridae, but there is insufficient information regarding it to warrant further genus placement (Calisher & Karabatsos, 1988). In Amazonia it has been isolated from a rodent (Dasyprocta aguti) and mosquitoes (Sabethesspp) and Oryzomys sp (Hervé ~., 1986). 20 Table 1. Togaviruses isolated in Brazilian Amazonia between 1954-1994. TAXONOMY ARTHROPOD VERTEBRATE HOSTS HUMAN VIRUS INFECTION Wild animals Laboratory Antigenic group Sentinel acquired Group A Mosquito mammals Bird Reptilian Others ** natural AURÁ * EEE 1 MAYARO MUCAMBO* PIXUNA * UNA* WEE 1 Not grouped TRINITI * Isolatesfirst roadein lhe IEC; ** Monkeys, chickens,and/or roice. 1. Isolations froro roanwere obtainedin othercountries. FLAVIVIRIDAE, Flavivirus (former group B arboviruses) Eight tlaviviruses have been isolated (Table 2) in the Amazon region. Bussuquara (BSQ) and Cacipacoré (CPC) viroses were previously unknown. Ilheus (ILH) virus has beenisolated for the first time in east region of Brazil. St. Louis encephalitis (SLE) virus was recovered for the first time in the USA. Yellow rever (YF) was originally isolated in Africa, and the dengue (DEN) virus (serotypes 1, 2, 3 and 4) have been before isolated in other continents. TAXONOMY ARTHROPODS VERTEBRATE HOSTS HUMAN VIRUS INFECTION Antigenic group Mosquito Others mammals Bird Sentinel natural Group B BUSSUQUARA* 1 CACIPACORÉ* DENGUE 1 DENGUE 2 DENGUE 4 ILHÉUS SLE YELLOW FEVER 2 21 BSQ vírus has beeo frequeotly isolated from seotioel mice andmonkeys, and wild rodeots (Proechimys guyannensis), as well as Culicidae mosquitoes. A siogle isolatioo ofCPC virus has beeo obtaioed from wild bird Perenosto/a rnbifrans. ILH virus has beeoisolated io Amazooia from febrile patieots, seotioel monkeys, ooce from a bat and and several times from mosquitoes principally Psorophora ferox. SLE virus has been isolated in Amazonia from forest birds, monkeys, marsupiaIs (Didelphis marsupia/is), sloth (Bradypus tridacty/us), monkey and chicken sentinels,Culicidade mosquitoes (chiefly Culex), once from Giganto//oe/aps sp rnites and twice from mau (Pinheiro ~., 1981; Travassos da Rosa ~., 1982). YF virus has beeo isolated from mosquitoes especially Haemagogus janihinomys,monkeys and mau whereas Dengue viroses have beeo isolated from mosquitoes Aedes aegypti and mau, These two viroses are described in more details in another chapters. BUNYA VIRIDAE The Bunyaviridae family of arbovirusesin the Amazon regionincludes 44 membersof the genus Bunyavirus 21 agents in the genus Phlebovi rus and few others provisionally placed in this family but that have not been assigned to a genus or group. GenusBunyavirus Within this genus (the fonner Bunyamwerasupergroup), 10 serogroupsarerecognized which are subdivided in ten serogroups on the basis oftheir antigenic relationships.Theyare : groups C, Anopheles A, Bunyamwera, Califomia, Capim, Gamboa, Guamá, Simbu, Turlock, and Pacora. Table 3 lists these viroses and it algo provides infonnation on the source of the isolares (Travassos da Rosa ~., 1986). Anopheles A group: Excepting Lukuni isolated from the first time from mosquitoes in Port of spain, Trinidad, lhe other viroses were isolated for the first time in lhe Brazilian Amazonia. In Amazon region Lukuni has been isolated only from mosquitoes (Aedes scapularis and Anopheles nimbus). Tacaiuma vírus is the only one responsible for naturally acquired human disease,and has algo beenisolated from mosquitoes (principally