Genetic and phenotypic characterization of the newly described insect flavivirus, Kamiti River virus

Division of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Fort Collins, Colorado 80522, USA.
Archives of Virology (Impact Factor: 2.39). 07/2003; 148(6):1095-118. DOI: 10.1007/s00705-003-0019-7
Source: PubMed


We have described in the accompanying paper by Sang, et al., ([57], Arch Virol 2003, in press) the isolation and identification of a new flavivirus, Kamiti River virus (KRV), from Ae. macintoshi mosquitoes that were collected as larvae and pupae from flooded dambos in Central Province, Kenya. Among known flaviviruses, KRV was shown to be most similar to, but genetically and phenotypically distinct from, Cell fusing agent virus (CFAV). KRV was provisionally identified as an insect-only flavivirus that fails to replicate in vertebrate cells or in mice. We report here the further characterization of KRV. Growth in cell culture was compared to that of CFAV; although growth kinetics were similar, KRV did not cause the cell fusion that is characteristic of CFAV infection. The KRV genome was found to be 11,375 nucleotides in length, containing a single open reading frame encoding 10 viral proteins. Likely polyprotein cleavage sites were identified, which were most similar to those of CFAV and were comparable to those of other flaviviruses. Sequence identity with other flaviviruses was low; maximum identity was with CFAV. Possible terminal secondary structures for the 5' and 3' non-coding regions (NCR) were similar to those predicted for other flaviviruses. Whereas CFAV was isolated from insect cells in the laboratory, the isolation of KRV demonstrates the presence of an insect-only flavivirus in nature and raises questions regarding potential interactions between this virus and other mosquito-borne viruses in competent vector populations. Additionally, this virus will be an important tool in future studies to determine markers associated with flavivirus host specificity.

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    • "To date, CFAV was already isolated from natural mosquito populations in Puerto Rico (Cook et al., 2006) and Thailand (Yamanaka et al., 2013), and was also detected in field-collected mosquitoes in Mexico (Espinoza-Gómez et al., 2011), Indonesia (Hoshino et al., 2009), and Argentina (GenBank accession numbers (GB): DQ335466-7). Other viruses related to CFAV were subsequently isolated directly from field-collected mosquitoes, such as Kamiti River virus (KRV) in Kenya (Crabtree et al., 2003; Sang et al., 2003); Culex flavivirus (CxFV) in Japan, Guatemala, USA, Mexico, Uganda, Caribbean, China, Brazil, and Argentina (Hoshino et al., 2007; Morales-Betoulle et al., 2008; Blitvich et al., 2009; Bolling et al., 2011; Cook et al., 2009; Kim et al., 2009; Farfan-Ale et al., 2010; Saiyasombat et al., 2010; Huanyu et al., 2012; Chen et al., 2013; Machado et al., 2012; Goenaga et al., 2014); Aedes flavivirus (AeFV) in Japan (Hoshino et al., 2009), Italy (Roiz et al., 2012; Grisenti et al., 2015), and USA (Haddow et al., 2013); Quang Binh virus (QBV) in Vietnam (Crabtree et al., 2009); Nakiwogo virus in Uganda (Cook et al., 2009); Calbertado virus in North America (Bolling et al., 2011; Tyler et al., 2011); Hanko virus in Finland (Huhtamo et al., 2012); Culex theileri flavivirus in Portugal (Parreira et al., 2012); Palm Creek virus in Australia (Hobson-Peters et al., 2013); and Nienokoue virus in Ivory Coast (GB: JQ957875). The isolation and characterization of an ISFV, Ochlerotatus caspius flavivirus (OcFV), from Aedes caspius mosquitoes collected in southern Portugal and closely related to the Hanko virus was recently reported (Ferreira et al., 2013). "
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    ABSTRACT: Several flaviviruses are important pathogens for humans and animals (Dengue viruses, Japanese encephalitis virus, Yellow-fever virus, Tick-borne encephalitis virus, West Nile virus). In recent years, numerous novel and related flaviviruses without known pathogenic capacity have been isolated worldwide in the natural mosquito population. However, phylogenetic studies have shown that genomic sequences of these viruses diverge from other flaviviruses. Moreover, these viruses seem to be exclusive of insects (they do not seem to grow on vertebrate cell lines), and were already defined as mosquito-only flaviviruses or insect-specific flaviviruses. At least eleven of these viruses were isolated worldwide, and sequences ascribable to other eleven putative viruses were detected in several mosquito species. A large part of the cycle of these viruses is not well known, and their persistence in the environment is poorly understood. These viruses are detected in a wide variety of distinct mosquito species and also in sandflies and chironomids worldwide; a single virus, or the genetic material ascribable to a virus, was detected in several mosquito species in different countries, often in different continents. Furthermore, some of these viruses are carried by invasive mosquitoes, and do not seem to have a depressive action on their fitness. The global distribution and the continuous detection of new viruses in this group point out the likely underestimation of their number, and raise interesting issues about their possible interactions with the pathogenic flaviviruses, and their influence on the bionomics of arthropod hosts. Some enigmatic features, as their integration in the mosquito genome, the recognition of their genetic material in DNA forms in field-collected mosquitoes, or the detection of the same virus in both mosquitoes and sandflies, indicate that the cycle of these viruses has unknown characteristics that could be of use to reach a deeper understanding of the cycle of related pathogenic flaviviruses. Copyright © 2015. Published by Elsevier B.V.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 07/2015; DOI:10.1016/j.meegid.2015.07.032 · 3.02 Impact Factor
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    • "Additionally , another group of flaviviruses that has been characterized in more recent years, the insect-specific flaviviruses (ISFs) are currently known to infect only insect hosts, primarily mosquitoes. These viruses include cell fusing agent virus (CFAV) (Cammisa- Parks et al., 1992; Stollar and Thomas, 1975), Kamiti River virus (KRV) (Crabtree et al., 2003; Sang et al., 2003) and many recently identified related viruses from different regions of the world (Cook et al., 2006, 2009, 2012; Crabtree et al., 2009; Farfan-Ale et al., 2009; Hoshino et al., 2007, 2009; Huhtamo et al., 2012; Kim et al., 2009; Morales-Betoulle et al., 2008). Interestingly, some of these ISFs appear to be capable of integrating their genomic sequences into mosquito genomes (Crochu et al., 2004). "
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    ABSTRACT: Novel flaviviruses that are genetically related to pathogenic mosquito-borne flaviviruses (MBFV) have been isolated from mosquitoes in various geographical locations, including Finland. We isolated and characterized another novel virus of this group from Finnish mosquitoes collected in 2007, designated as Ilomantsi virus (ILOV). Unlike the MBFV that infect both vertebrates and mosquitoes, the MBFV-related viruses appear to be specific to mosquitoes similar to the insect-specific flaviviruses (ISFs). In this overview of MBFV-related viruses we conclude that they differ from the ISFs genetically and antigenically. Phylogenetic analyses separated the MBFV-related viruses isolated in Africa, the Middle East and South America from those isolated in Europe and Asia. Serological cross-reactions of MBFV-related viruses with other flaviviruses and their potential for vector-borne transmission require further characterization. The divergent MBFV-related viruses are probably significantly under sampled to date and provide new information on the variety, properties and evolution of vector-borne flaviviruses.
    Virology 09/2014; s 464–465(1):320–329. DOI:10.1016/j.virol.2014.07.015 · 3.32 Impact Factor
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    • "The first described was the Cell fusing agent virus isolated on a mosquito cell culture [8]. To date, the ISF group includes several members, including the Kamiti River virus isolated in Kenya in 1999 [9, 10], Culex flavivirus first isolated from Culex mosquitoes in Japan and Indonesia in 2003–2004 [11], and Aedes flavivirus (AeFV) found in Aedes albopictus in Japan in 2003–2004 [12]. In Europe, the first ISF isolation was reported in Spain from Cx. spp. "
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    ABSTRACT: Background The genus Flavivirus comprises several mosquito-borne species, including the zoonotic pathogens West Nile and Usutu virus, circulating in animals and humans in Italy since 1998. Due to its ecological and geographical features, Piedmont is considered a risk area for flavivirus transmission. Here we report the results of a flavivirus survey (detection and genetic characterization) of mosquitoes collected in Piedmont in 2012 and the genetic characterization of three strains detected in 2011. Methods Pools of 1-203 mosquitoes, upon RNA extraction with TRIzol, were screened by a PCR assay for a 263 bp fragment of the Flavivirus NS5 gene. All positive samples were tested with a specific PCR for the E protein gene of Usutu virus and a generic Flavivirus RT-nested-PCR for a larger tract of the NS5 gene before sequencing. Phylogenetic trees were built with both NS5 fragments of representative Flavivirus species. DNA extracts of part of the positive pools were tested to detect sequences integrated in the host genome. Results Thirty-four mosquito pools resulted positive for flaviviruses, and twenty-five flavivirus sequences underwent phylogenetic analysis for the short NS5 fragment. Among the 19 sequences correlating with the insect-specific flavivirus group, ten samples, retrieved from Aedes albopictus, clustered within Aedes flavivirus, while the other nine aggregated in a separate clade composed of strains from various mosquito species (mainly Aedes vexans) from Piedmont and the Czech Republic. Six out of these nine also presented a DNA form of the sequence. The remaining sequences belonged to the mosquito-borne group: four, all from Culex pipiens, correlated to Italian Usutu virus strains, whereas two, from Ochlerotatus caspius, were highly similar to Marisma mosquito virus (MMV). Conclusions Our findings confirm the circulation of Usutu virus and of the potentially zoonotic Marisma mosquito virus in Piedmont. This is the first detection of Aedes flavivirus in Piedmont. Finally, further evidence for the integration of Flavivirus nucleic acid into the host genome has been shown. These results underline the importance of continuing intense mosquito-based surveillance in Piedmont, supported by a mosquito control program in areas at high risk for human exposure.
    Parasites & Vectors 08/2014; 7(August 2014):395. DOI:10.1186/1756-3305-7-395 · 3.43 Impact Factor
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