BackgroundDengue viruses (DENVs) are mosquito-borne viruses which can cause disease ranging from mild fever to severe dengue infection. These viruses are endemic in several tropical and subtropical regions. Multiple outbreaks of DENV serotypes 1, 2 and 3 (DENV-1, DENV-2 and DENV-3) have been reported from the western region in Saudi Arabia since 1994. Strains from at least two genotypes of DENV-1 (Asia and America/Africa genotypes) have been circulating in western Saudi Arabia until 2006. However, all previous studies reported from Saudi Arabia were based on partial sequencing data of the envelope (E) gene without any reports of full genome sequences for any DENV serotypes circulating in Saudi Arabia.FindingsHere, we report the isolation and the first complete genome sequence of a DENV-1 strain (DENV-1-Jeddah-1-2011) isolated from a patient from Jeddah, Saudi Arabia in 2011. Whole genome sequence alignment and phylogenetic analysis showed high similarity between DENV-1-Jeddah-1-2011 strain and D1/H/IMTSSA/98/606 isolate (Asian genotype) reported from Djibouti in 1998. Further analysis of the full envelope gene revealed a close relationship between DENV-1-Jeddah-1-2011 strain and isolates reported between 2004–2006 from Jeddah as well as recent isolates from Somalia, suggesting the widespread of the Asian genotype in this region.ConclusionsThese data suggest that strains belonging to the Asian genotype might have been introduced into Saudi Arabia long before 2004 most probably by African pilgrims and continued to circulate in western Saudi Arabia at least until 2011. Most importantly, these results indicate that pilgrims from dengue endemic regions can play an important role in the spread of new DENVs in Saudi Arabia and the rest of the world. Therefore, availability of complete genome sequences would serve as a reference for future epidemiological studies of DENV-1 viruses.

A cell line from the main insect pest of potatoes in tropical and subtropical areas, Phthorimaea operculella (Zeller), was obtained from embryoculture. These cells were cultured in Grace's modified medium. The cell line, designated ORS-Pop-93, had a heterogeneous population consisting of spherical and spindle cells with great capacity to adhere and a doubling time of 40 h. They were subcultured for more than 60 passages. Their polypeptidic profile was different from profiles of other lepidopteran cell lines. The cell line supports the multiplication of the Autographa californica nuclear polyhedrosis virus.

No abstract

Three selected uncloned Pop 2, Pop 3, Pop 4 and two cloned cell lines Pop cl1A and Pop cl2B were derived from the original cell line established from Phthorimaea operculella (ORS-Pop-93). Three new non-selected cell lines ORS-Pop-94A, ORS-Pop-94B and ORS-Pop-95 were also established from embryos of the same insect. Differences in morphology, growth rate and polypeptide profile were determined between these cell lines. All the cell lines were susceptible to the Autographa californica nucleopolyhedrovirus (AcMNPV). The cloned cell lines produced higher levels of AcMNPV (TCID-50 and PIB) than the parental cells and at the same rate as the Sf9 reference cell line. Substantial amounts of viral DNA were synthesized in the clone Pop cl 2B after infection with the granulosis virus of the potato tuber moth P. operculella (PTMGV) and a complete multiplication was obtained in the ORS-Pop-95 cell line. The comparison between Pop cell lines which support limited or complete replication of certain baculoviruses can offer insights into some of the molecular barriers which restrict the host range of these viruses. These cell lines with variable susceptibility to baculoviruses could also be used for in vitro recombinations, increasing their virus host range to be used for the control of this pest.

A newly established cell line was obtained from the culture of embryonic cells of the potato tuber moth Phthorimaea operculella in low temperature conditions (19 degrees C) using modified Grace's medium supplemented with 10% fetal bovine serum. The population doubling time was about 80 h when cells were cultivated at 19 degrees C and 38 h at 27 degrees C. The cell line had a relatively homogeneous population consisting of various sized spherical cells. The cells were cultivated for more than 25 passages. Their polypeptidic profile was different from profiles of other P. operculella cell lines we previously described and from other lepidopteran cells. The new cell line was designated ORS-Pop-95. The complete replication of the potato tuber moth granulosis virus (PTM GV) was obtained in vitro by both viral infection and DNA transfection. PTM GV multiplied at a significant level during several passages of the cell line that was maintained at 19 degrees C. As long as the cells were maintained at 19 degrees C, virus multiplication could also be obtained at the same rate at 27 degrees C. To compare PTM GV multiplied both in vivo and in vitro, we used morphological identification, serological, DNA probe diagnosis and endonuclease digest profile analysis and confirmed the identity of the virus.