The tree is based on C-prM regions (nt194-522, 329 bp) of the selected strains. Each geographical strain is abbreviated by its accession Vactosertib concentration number followed by country and year of isolation. Figure 2 Phylogenetic

tree of studied sequences with geographical strains of serotype 3 by neighbor-joining method. The tree is based on C-prM regions (nt200-418, 219 bp) of the selected strains. Each geographical strain is abbreviated by its accession number followed by country and year of isolation. Discussion Over the years dengue fever has become an important arboviral infection in different geographical regions of the world that supports the growth of mosquitoes. Its range exceeds over a hundred tropical and subtropical countries with more than 2.5 billion people at the risk of infection [12]. Pakistan has witnessed some severe outbreaks of dengue viral infection leading to significant morbidity and mortality since 1994 [20, 21]. Since the publication of a study in 1982 documenting dengue infection from the years 1968 and 1978 [19], several mini outbreaks of dengue viral infection have been reported. No doubt all the four distinct serotypes, DEN-1, DEN-2, DEN-3, and DEN-4 of dengue virus have been reported as the cause of dengue infection; however, serotypes DEN-2 and DEN-3 remained the major cause of infection in humans world-wide. Like other parts of

the world, in the current study we have observed that serotypes DEN-2 and DEN-3 are the MDV3100 price predominant serotypes in dengue infection in outbreaks of 2007, 2008 and 2009 in Pakistan. In 2007, serotype DEN-2 prevailed with less occurrence of serotype DEN-3. In samples Protein Tyrosine Kinase inhibitor of 2008 and 2009, serotype DEN-3 has been isolated, though first incidence of serotype 3 infections Cell press was reported by Jamil and colleagues [20] in year 2005 outbreak in Karachi. This shows that serotype 3 is new comer to this region as was isolated for the first time in year 2005. All the previous outbreaks have been attributed to other serotypes. From Lahore, Hamayoun

and colleagues [21] reported only serotype DEN-3 in 2008 outbreak and they were unable to isolate any other serotype. This finding of Hamayoun [21] confirms the results of our study as serotype 3 is the only serotype we have seen from stored samples of that particular outbreak of 2008. In the present study we were able to characterize a very low number of suspected dengue samples (17.5%; 20 samples out of 114) on molecular level. This may be due to the reason that majority of samples were collected from suspected gangue virus infected patients in post viremic phase. For the correct molecular characterization of the virus, samples should be collected in acute phase of infection. Presentation of patients in post viremic phase or lower rate of viral isolation may be the reason of getting only twenty samples with positive results for dengue virus [4].