Propiedades biológicas de cepas venezolanas de DENV-2 aisladas de pacientes con fiebre de dengue y fiebre hemorrágica del dengue

introduction: the dengue virus causes a growing public health problem, but it has not been possible yet to determine the role of some biological attributes in the virulence and /or pathogeneity of viral serotypes. objective: to evaluate the in vitro and in vivo biological properties of 4 venezuelan denv-2 strains (lar1693, lar19094, lar2303, ihn35262) responsible for dengue fever and dengue hemorrhagic fever and the reference strain (16681) isolated from a patient suffering dengue hemorrhagic fever and dengue shock syndrome. methods: the evaluated strains were isolated from sera of viremic patients with dengue fever and dengue hemorrhagic fever. they were then subjected to the plaque titration assay in bhk-21 cell line in order to determine the plaque size and kinetics of viral replication. the length of time and intensity of cytopathic effect and specific immunofluorescence on the c6/36-ht cell line was evaluated by optical microscopy and fluorescence respectively. additionally, the flow cytometry to quantify viral replication in c6/36-ht cells and the intracerebral inoculation in newborn mice to find out neurovirulence were both used. results: all strains, except for 16681, showed small plaques at 0.01 m.o.i. the viral replication in c6/36-ht was higher for 16681 strain. through cytophatic effect observations the strains were classified with low (lar19094 and lar2303), mild (inh35262 y 16681) and high (lar1693) cytophatogeneity. the specific immunofluoresce ranged 5 to 50 % in the first day post inoculation, except for 16681 strain. the neurovirulence in newborn mices inoculated with 104 pfu/ml yielded 77.5 (inh35262) to 100% (lar1693 y 16681) mortality rate and variability during survival days. the viral replication at 24.36 and 48 hours after inoculation was assessed by flow cytometry, ranging from 3.33 to 90.3% conclusions: the results led to the conclusion that viral strain behaviors were not sound evidence to correlate these in vitro e in vivo biological attr