title: Occurrence of natural vertical transmission of dengue-2 and dengue-3 viruses in Aedes aegypti and Aedes albopictus in Fortaleza, Ceará, Brazil.
abstract: BACKGROUND
  Aedes aegypti and Aedes albopictus perform an important role in the transmission of the dengue virus to human populations, particularly in the tropical and subtropical regions of the world. Despite a lack of understanding in relation to the maintenance of the dengue virus in nature during interepidemic periods, the vertical transmission of the dengue virus in populations of A. aegypti and A. albopictus appears to be of significance in relation to the urban scenario of Fortaleza.
  
  
  METHODS
  From March 2007 to July 2009 collections of larvae and pupae of Aedes spp were carried out in 40 neighborhoods of Fortaleza. The collections yielded 3,417 (91%) A. aegypti mosquitoes and 336 (9%) A. albopictus mosquitoes. Only pools containing females, randomly chosen, were submitted to the following tests indirect immunofluorescence (virus isolation), RT-PCR/nested-PCR and nucleotide sequencing at the C-prM junction of the dengue virus genome.
  
  
  RESULTS
  The tests on pool 34 (35 A. albopictus mosquitoes) revealed with presence of DENV-3, pool 35 (50 A. aegypti mosquitoes) was found to be infected with DENV-2, while pool 49 (41 A. albopictus mosquitoes) revealed the simultaneous presence of DENV-2 and DENV-3. Based on the results obtained, there was a minimum infection rate of 0.5 for A. aegypti and 9.4 for A. albopictus. The fragments of 192 bp and 152 bp related to DENV-3, obtained from pools 34 and 49, was registered in GenBank with the access codes HM130699 and JF261696, respectively.
  
  
  CONCLUSIONS
  This study recorded the first natural evidence of the vertical transmission of the dengue virus in populations of A. aegypti and A. albopictus collected in Fortaleza, Ceará State, Brazil, opening a discuss on the epidemiological significance of this mechanism of viral transmission in the local scenario, particularly with respect to the maintenance of these viruses in nature during interepidemic periods.
authors: Human Biochemistry Laboratory, State University of Ceará, Fortaleza, Ceará, Brazil. victorpessoabiologo@yahoo.com.br
authors: Victor Emanuel Pessoa
authors: VE
authors: Martins
authors: Carlos Henrique
authors: CH
authors: Alencar
authors: Michel Toth
authors: MT
authors: Kamimura
authors: Michel Tott
authors: MT
authors: Kamimura
authors: Fernanda Montenegro
authors: FM
authors: de Carvalho Araújo
authors: Salvatore Giovanni
authors: SG
authors: De Simone
authors: Rosa Fireman
authors: RF
authors: Dutra
authors: Maria Izabel Florindo
authors: MI
authors: Guedes
mesh_terms: D000330:Aedes / Q000821:virology*; D000818:Animals; D001938:Brazil; D003715:Dengue / Q000453:epidemiology / Q000635:transmission; D003716:Dengue Virus; D005260:Female; D006801:Humans; D018445:Infectious Disease Transmission, Vertical; D007303:Insect Vectors / Q000821:virology*; D007814:Larva / Q000821:virology; D008297:Male