Experimental Transmission of Rocio Virus by Mosquitoes

Cj, Mitchell; Tp, Monath; Cb, Cropp

doi:10.4269/ajtmh.1981.30.465

Cited by 18 publications

(10 citation statements)

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“…Several other members of the Culex-borne virus clade that do not meet this specific vector-disease syndrome relationship (Gaunt et al, 2001) include Koutango and Saboya viruses that have been isolated more often from ticks and sandflies, respectively, and which are not known to be neurotropic. Nonetheless, the above generalization (Gaunt et al, 2001) can still be applied to ROCV, because it is a neurotropic virus that can replicate in Culex mosquitoes at least under laboratory conditions (Mitchell et al, 1981).…”

Section: Discussionmentioning

confidence: 99%

Complete genome characterization of Rocio virus (Flavivirus: Flaviviridae), a Brazilian flavivirus isolated from a fatal case of encephalitis during an epidemic in São Paulo state

Medeiros

Nunes

Vasconcelos

et al. 2007

Journal of General Virology

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The flaviviruses of major medical importance in South American countries are yellow fever, dengue, Saint Louis encephalitis, West Nile and Rocio viruses. Rocio virus (ROCV) has been responsible for epidemics of severe encephalitis in Brazil with a case-fatality rate of 10 % and development of sequelae in 20 % of the survivors. We have sequenced and characterized the entire genome of ROCV for the first time, by determining the general traits of the open reading frame and the characteristics of viral genes including the potential cleavage sites, conserved or unique motifs, cysteine residues and potential glycosylation sites. The conserved sequences in the 39-non-coding region were identified, and the predicted secondary structures during cyclization between 59-and 39-non-coding regions were studied. Multiple protein and phylogenetic analyses based on antigenically important and phylogenetically informative genes confirmed a close relationship between ROCV and Ilheus virus (ILHV), together constituting a unique and distinct phylogenetic subgroup as well as the genetic relationship of ROCV with several members of the Japanese encephalitis group. Although ROCV is phylogenetically related to ILHV, our study shows that it is still a virus distinct from the latter virus. This is the first flavivirus uniquely indigenous to Brazil that has been sequenced completely and the genome characterized. The data should be useful for further studies at the molecular level, including construction of infectious clone, identification of gene function, improved disease surveillance based on molecular diagnostic tools and vaccine development. INTRODUCTIONIn South America, until the mid-1970s, the two neurotropic flaviviruses had been Saint Louis encephalitis virus (SLEV) and Ilheus virus (ILHV). However, in contrast to North America, an epidemic of encephalitis in humans by SLEV in South America was not recorded for many years until the first outbreak in Argentina in 2005(Diaz et al., 2006, despite accumulated records of virus isolation from mosquitoes and vertebrate hosts throughout the continent (Spence, 1980). As for the other virus, ILHV, human infection was sporadic and development of neurotropic manifestations has been even more infrequent. Thus, the sudden emergence of an outbreak of encephalitis caused by a flavivirus in 1974-75 in Brazil was unexpected.Rocio virus (ROCV) belongs to the genus Flavivirus in the family Flaviviridae. Its prototype (strain SPH 34675) was isolated in Ribeira Valley in the south-eastern São Paulo state of Brazil in 1975 from the cerebellum of a fatal human case during an epidemic of encephalitis that could not be readily diagnosed with the reagents then available for known encephalitic viruses. The epidemic, which began in 1974, spread to more than 20 municipalities over the following 2 years causing approximately 1000 diagnosed cases.Members of the genus Flavivirus (hereafter called flaviviruses) are positive-sense, single-stranded RNA viruses that infect humans and other vertebrates. They are mainly...

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Section: Discussionmentioning

confidence: 99%

Complete genome characterization of Rocio virus (Flavivirus: Flaviviridae), a Brazilian flavivirus isolated from a fatal case of encephalitis during an epidemic in São Paulo state

Medeiros

Nunes

Vasconcelos

et al. 2007

Journal of General Virology

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“…During the epidemic, there was a case-fatality rate of 13%, with approximately 20% of survivors developing long-term neurological sequelae. Laboratory studies suggest that ROCV is mosquito-transmitted, as Culex tarsalis and C. pipiens were efficient experimental vectors 218 , and that birds may act as amplifying hosts 219 . Although no cases of ROCV infection and encephalitis have been reported after the initial outbreak, serological surveys suggest ROCV transmission among humans and animals in different regions of Brazil is still actively occurring 220,221 .…”

Section: Ilheus Virusmentioning

confidence: 99%

The continued threat of emerging flaviviruses

Pierson

Diamond²

2020

Nat Microbiol

677

627

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F laviviruses are single-stranded RNA viruses vectored principally by arthropods that cause severe illnesses in humans. The extensive global spread and epidemic transmission of flaviviruses during the last seven decades has been remarkable. The mosquito-borne dengue viruses (DENV) infect an estimated 400 million humans each year; more than a quarter of the world's population lives in areas where DENV is now endemic 1 . By comparison, only sporadic DENV epidemics were documented before the Second World War 2 . The introductions of West Nile (WNV) and Zika (ZIKV) viruses into the Western Hemisphere was followed by rapid geographical spread, large numbers of human infections and considerable morbidity 3,4 . Ongoing yellow fever virus (YFV) transmission and its encroachment on urban environments, despite the existence of an effective vaccine, poses a serious public health challenge 5-7 . Other flaviviruses present ongoing health risks or are beginning to emerge in different parts of the world, including Japanese encephalitis virus (JEV), tick-borne encephalitis virus (TBEV) and Usutu virus (USUV).The epidemic potential of flaviviruses reflects many factors related to the unique characteristics of their insect vectors, the consequences of poorly planned urbanization that creates ideal arthropod breeding habitats, the geographical expansion of vectors, changing environmental conditions and extensive global travel 8,9 . Beyond arthropods and humans, flaviviruses are also known to infect a wide array of animal species and can be important veterinary pathogens that threaten economically important domesticated animals 10-14 . These vertebrate animal hosts may constitute important stable reservoirs and contribute to defining conditions that support the introduction of new viral species and transmission among humans 15 . The continued threat of flavivirus emergence and re-emergence highlights a need for a detailed fundamental understanding of the biology of these viruses, the immune responses that can contain them and the possible countermeasures that can blunt their impact on public health should new outbreaks occur. Flavivirus structure and replicationFlaviviruses are small (~50 nm) spherical virus particles that incorporate a single genomic RNA of positive-sense polarity encoding three structural and seven non-structural proteins (Fig. 1a). Our knowledge of the biology of flaviviruses has advanced considerably with the availability of high-resolution structures of viral structural proteins and of virions at different stages of the replication cycle or in complex with antibodies or host factors 16 . Crystal structures of the enzymatic non-structural proteins also have been solved, accelerating advances in an understanding of virus replication and pathogenesis [17][18][19] and enabling structure-guided drug discovery, as reviewed elsewhere 20 .Virion structure and morphogenesis. Flaviviruses are assembled using three viral structural proteins (C, prM and E), a host lipid envelope and the viral genomic RNA. The structure of ...

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“…For the first time in history, from 1975 to 1977, the new flavivirus was responsible for a severe and extensive encephalitis epidemic in the southeastern coast of the São Paulo State, Brazil 6,7,17,22,29 . The ecology of the viral transmission cycle of ROCV remains unknown but there is strong evidence indicating that birds and mosquitoes are involved 7,8,12,17,18,21,22 . During the epidemic period, the dominant geographic area was the forest, inhabited predominantly by rural population.…”

Section: Discussionmentioning

confidence: 99%

“…The ecology of the viral transmission cycle remains unknown but there is strong evidence indicating that birds and mosquitoes may be involved 6,7,8,12,17,21 .…”

Section: Introductionmentioning

confidence: 99%

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Molecular characterization of two rocio flavivirus strains isolated during the encephalitis epidemic in são paulo state, brazil and the development of a one-step rt-pcr assay for diagnosis

Coimbra

Santos

Petrella

et al. 2008

Rev. Inst. Med. trop. S. Paulo

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SUMMARYRocio virus (ROCV) was responsible for an explosive encephalitis epidemic in the 1970s affecting about 1,000 residents of 20 coastland counties in São Paulo State, Brazil. ROCV was first isolated in 1975 from the cerebellum of a fatal human case of encephalitis. Clinical manifestations of the illness are similar to those described for St. Louis encephalitis. ROCV shows intense antigenic cross-reactivity with Japanese encephalitis complex (JEC) viruses, particularly with Ilheus (ILHV), St. Louis encephalitis, Murray Valley and West Nile viruses. In this study, we report a specific RT-PCR assay for ROCV diagnosis and the molecular characterization of the SPAn37630 and SPH37623 strains. Partial nucleotide sequences of NS5 and E genes determined from both strains were used in phylogenetic analysis. The results indicated that these strains are closely related to JEC viruses, but forming a distinct subclade together with ILHV, in accordance with results recently reported by MEDEIROS et al. (2007).

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Experimental Transmission of Rocio Virus by Mosquitoes

Cited by 18 publications

References 0 publications

Complete genome characterization of Rocio virus (Flavivirus: Flaviviridae), a Brazilian flavivirus isolated from a fatal case of encephalitis during an epidemic in São Paulo state

Complete genome characterization of Rocio virus (Flavivirus: Flaviviridae), a Brazilian flavivirus isolated from a fatal case of encephalitis during an epidemic in São Paulo state

The continued threat of emerging flaviviruses

Molecular characterization of two rocio flavivirus strains isolated during the encephalitis epidemic in são paulo state, brazil and the development of a one-step rt-pcr assay for diagnosis

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