Ilheus virus isolate from a human, Ecuador.To the Editor: Ilheus virus (ILHV) (genus Flavivirus in the Ntaya antigenic complex) is most closely related to Rocio virus. However, antibodies produced during ILHV infection cross-react in serologic assays to other flavivirus antigens, and ILHV was originally classified in the Japanese encephalitis antigenic complex (1-3). ILHV is transmitted in an enzootic en·zo·ot·ic adj. Prevalent among or restricted to animals of a specific geographic area. Used of a disease. n. An enzootic disease. enzootic peculiar to or present constantly in a location. See also endemic. cycle between birds and mosquitoes. Since the first isolation of ILHV from a pool of Aedes spp. and Psorophora spp. mosquitoes collected in 1944 at Ilheus City, on the eastern coast of Brazil (4), isolates have been obtained in Central and South America and Trinidad, primarily from Psorophora ferox mosquitoes (5,6). ILHV is not associated with epidemic disease and has been only sporadically isolated from humans (5,7-9). The clinical spectrum of human infections documented by virus isolation ranges from asymptomatic to signs of central nervous system involvement suggestive of encephalitis. Most commonly, patients exhibit a mild febrile illness accompanied by headache, myalgia, arthralgia, and photophobia photophobia /pho·to·pho·bia/ (-fo´be-ah) abnormal visual intolerance to light.photopho´bic pho·to·pho·bi·a n. 1. , symptoms that may result in clinical diagnosis of dengue, Saint Louis encephalitis Saint Lou·is encephalitis n. A viral encephalitis occurring in parts of North America and transmitted by a mosquito of the genus Culex. , yellow fever, or influenza (7). Laboratory diagnosis of ILHV infection may be difficult, unless a virus isolate can be obtained, because of the cross-reactivity in serologic assays to other flaviviruses that circulate in the same area, such as Rocio, dengue, yellow fever, and Saint Louis encephalitis viruses. On March 1, 2004, after 4 days of symptoms, a 20-year-old male soldier stationed in Lorocachi, Ecuador, was admitted to the Hospital de la IV Division del Ejercito "Amazonas" in Puyo, Ecuador. Lorocachi is in the Amazonian province of Pastaza, of which Puyo is the capital. The patient had fever, rash, epistaxis epistaxis /ep·i·stax·is/ (-stak´sis) nosebleed; hemorrhage from the nose, usually due to rupture of small vessels overlying the anterior part of the cartilaginous nasal septum. ep·i·stax·is n. , headache, myalgia, retroocular ret·ro·oc·u·lar adj. Situated behind the eye. pain, nausea, vomiting, jaundice, sore throat, and abdominal pain. A blood specimen (containing isolate FSE FSE 1. feline spongiform encephalopathy. 2. focal symmetrical encephalomalacia. 800) was collected, and an acute-phase serum sample was processed for virus isolation in C6/36 (Aedes albopictus) and Vero cells. After 3 days, cytopathic effects were observed, and cells were screened by an immunofluorescence assay for reactivity against alphaviruses and flaviviruses by using polyclonal antibodies. The cells gave positive results with yellow fever, Saint Louis encephalitis, Rocio, and Ilheus antisera. Viral RNA RNA: see nucleic acid. RNA in full ribonucleic acid One of the two main types of nucleic acid (the other being DNA), which functions in cellular protein synthesis in all living cells and replaces DNA as the carrier of genetic was then extracted from the patient's acute-phase serum and cell supernatants and processed for virus sequencing. Amplification of an [approximately equal to] 250-bp product by SyBRgreen real-time reverse transcriptase PCR RT-PCR is a one or two-step process for converting RNA to DNA and the subsequent amplification of the reversely-transcribed DNA. In the first step of RT-PCR, called the “first strand reaction,” complementary DNA (cDNA) is made from an mRNA template using and subsequent sequencing of the amplicon were conducted with the flavivirus consensus primers FU1 and cFD2 (2). Viruses were identified by BLAST search (www.ncbi.nlm.nih. gov/blast) and alignment to GenBank sequences. FSE800 had 96% identity (182 of 188 bp) with the nonstructural (NS) 5 region of the original ILHV strain AY632539 (1). An ILHV original 1944 isolate used as positive control had 100% sequence identity with AY632539. Limited sequence information is available in GenBank for ILHV outside of the conserved NS5 region. Therefore, further sequencing of the NS5 region using flavivirus consensus primers FU1 and cFD3 (2) and the complete envelope (E) gene region, based on the complete open reading frame ILHV nucleotide sequence AY632539 (1), was conducted on FSE800, as well as a low-passage original 1944 isolate (R. Tesh, University of Texas Medical Branch "UTMB" redirects here. For other system schools, see University of Texas System. The University of Texas Medical Branch (UTMB) is a component of the University of Texas System located in Galveston, Texas, about 50 miles (80 km) southeast of downtown Houston. [UTMB UTMB University of Texas Medical Branch ]), 2 mosquito isolates from Iquitos, Peru (R. Tesh, UTMB), and 2 human isolates from Brazil (CDC See Control Data, century date change and Back Orifice. CDC - Control Data Corporation ) (8) (Figure). There was 100% sequence identity among the 2 Brazilian and 2 Peruvian isolates at both gene regions. In the NS5 region, there was 100% identity between Brazilian and original isolates; 95% identity between FSE800 and Brazilian-original isolates; 98% identity between FSE800 and Peruvian isolates; and 96% identity between Peruvian and original-Brazilian isolates. At the protein level, 3 amino acid (aa) differences were found between FSE800 and original-Brazilian isolates, 2 between FSE800-Peruvian and original-Brazilian isolates (aa 3086, Lys-Gln; aa 3138, Ala-Val) and 1 between FSE800 and original-Brazilian-Peruvian isolates (aa 3309, Asp-Asn). [FIGURE OMITTED] In the E gene region, there was 99.9% identity between original and Brazilian isolates; 95.1% and 95% identity between FSE800 and original and Brazilian isolates, respectively; 98.5% identity between FSE800 and Peruvian isolates; and 95.3% identity between Peruvian and original isolates. At the protein level, 2 aa differences were found between original-Brazilian and Peruvian-FSE800 isolates (aa 432, Ile-Thr; aa 652, Lys-Asn), 1 aa change only in Brazilian isolates (aa 570, His-Tyr), and 1 only in Peruvian isolates (aa 675, Asn-Ser). With the exception of the Ala-Val change, all were nonconservative changes. The effect of the amino acid changes has yet to be determined. However, nucleotide sequence comparison between the 6 ILHV isolates has shown that these gene regions are highly conserved geographically and temporally. Ilheus virus is not usually associated with human disease, and human ILHV infections may not be correctly identified without a virus isolate because of the similar clinical symptoms and cross-reactivity in serologic assays to other flaviviruses. As laboratory surveillance is enhanced to monitor the emergence of West Nile virus West Nile virus, microorganism and the infection resulting from it, which typically produces no symptoms or a flulike condition. The virus is a flavivirus and is related to a number of viruses that cause encephalitis. in Central and South America, detection of ILHV and other flaviviruses may increase. Acknowledgments We thank Alfredo Huaman and Roxana Caceda for their expert serologic and isolation assistance, respectively; Robert Tesh for contribution of the 3 ILHV isolates; and Robert S. Lanciotti and Goro Kuno for technical assistance. References (1.) Kuno G, Chang GJ. Biological transmission of arboviruses arboviruses (ar´bōvī´r  sz),n. : reexamination of and new insights into components, mechanisms, and unique traits as well as their evolutionary trends. Clin Microbiol Rev. 2005;18:608-37. (2.) Kuno G, Chang GJ, Tsuchiya KR, Karabatsos N, Cropp CB. Phylogeny of the genus Flavivirus. J Virol. 1998;72:73-83. (3.) Monath TP, Heinz F. Flaviviruses. In: Knipe D, Howley P, editors. Fields virology. 4th ed. Philadelphia: Lippincott Williams and Wilkins; 1996. p. 1043-125. (4.) Laemmert H, Hughes T. The virus of Ilheus encephalitis: isolation, serological serological pertaining to or emanating from serology. serological test one involving examination of blood serum usually for antibody. specificity and transmission. J Immunol. 1947;55:61-7. (5.) Srihongse S, Johnson CM. The isolation of Ilheus virus from a man in Panama. Am J Trop Med Hyg. 1967;16:516-8. (6.) Pinheiro F, Travassos da Rosa A. Ilheus fever. In: Beran G, Steel J, editors. CRC (Cyclical Redundancy Checking) An error checking technique used to ensure the accuracy of transmitting digital data. The transmitted messages are divided into predetermined lengths which, used as dividends, are divided by a fixed divisor. handbook of zoonoses Zoonoses Infections of humans caused by the transmission of disease agents that naturally live in animals. People become infected when they unwittingly intrude into the life cycle of the disease agent and become unnatural hosts. . Boca Raton (FL): CRC Press; 1994. p. 210. (7.) Figueiredo LT. The Brazilian flaviviruses. Microbes Infect. 2000;2:1643-9. (8.) Nassar ES, Coimbra TL, Rocco IM, Pereira LE, Ferreira IB, de Souza LT, et al. Human disease caused by an arbovirus arbovirus Any of a large group of viruses that develop in arthropods (chiefly mosquitoes and ticks). The name derives from “arthropod-borne virus.” The spheroidal virus particle is encased in a fatty membrane and contains RNA; it causes no apparent harm to the closely related to Ilheus virus: report of five cases. Intervirology. 1997;40:247-52. (9.) Prias-Landinez E, Bernal-Cubides C, Morales-Alarcon A. Isolation of Ilheus virus from a man in Colombia. Am J Trop Med Hyg. 1968;17:112-4. (10.) Kumar S, Tamura K, Nei M. MEGA3: integrated software for molecular evolutionary genetics analysis and sequence alignment. Brief Bioinform. 2004;5:15-63. Barbara W. Johnson, * Cristopher Cruz, ([dagger]) Vidal Felices, ([dagger]) William R. Espinoza, ([double dagger]) Stephen Robert Manock, ([section]) Carolina Guevara, ([dagger]) James G. Olson, ([dagger]) and Tadeusz J. Kochel ([dagger]) * Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. , Fort Collins, Colorado The City of Fort Collins, a home rule municipality situated on the Cache la Poudre River along the Colorado Front Range, is the county seat and most populous city in Larimer County, Colorado. , USA; ([dagger]) US Naval Medical Research Center Detachment, Lima, Peru; ([double dagger]) Hospital de la IV Division del Ejercito "Amazonas," Puyo, Ecuador; and ([section]) Hospital Vozandes del Oriente. Shell, Ecuador Address for correspondence: Barbara W. Johnson, Arbovirus Diseases Branch, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, 3150 Rampart Rd, Fort Collins, CO 80521, USA; email: bfj9@ cdc.gov |
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