iPURSE

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Browsing iPURSE by Author "Abeykoon, A.M.S.B."

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    Cellular and virological changes with reference to cytopathic effect and virus load in dengue virus co-infections and super-infections in vitro
    (University of Peradeniya, 2016-11-05) Fara, M.M.F.; Daulagala, S.W.P.L.; Sirisena, P.D.N.N.; Abeykoon, A.M.S.B.; Noordeen, F.
    Dengue virus (DENV) infection is caused by different DENV types: DENV-1, DENV-2, DENV-3 and DENV-4 depending on the prevalence of these types in a particular locale. Since 1960, all four DENV serotypes have been circulating in Sri Lanka and now these DENV types are hyper-endemic. Risk of co- and super-infection is high in a country like Sri Lanka due to the hyper-endemicity of these viruses. There have been a few case reports on DENV co-infections in patients in Sri Lanka. However, experimental studies on co- and super- infections are scanty to understand the virological and cellular changes in co- or super- infections with different DENV serotypes. Hence, this study was conducted to understand the virological (virus load) and cellular changes (cytopathic effect - CPE) in experimental co- and super-infections with different DENV serotypes in Vero cells. Each DENV serotype was used to infect the Vero cells and incubated for 96 hrs. Cells were observed using the inverted microscope for CPE every 24 hours. After 96 hours of incubation, different DENV was/were harvested along with the Vero cells and the viral RNA was extracted using a validated RNA extraction system (Qiagen, Hilden, Germany). The DENV RNA samples were then subjected to quantitative reverse transcription polymerase chain reaction (qRT-PCR) to determine the viral loads in different infections used for the experiment. The current study shows that the DENV-2 is an aggressive CPE producer. DENV-1 causes less CPE in Vero cells when compared to DENV-3. DENV-4 does not cause much CPE in Vero cells. DENV-2 has a higher ability to co-infect with other DENV serotypes and it can produce a high number of progeny comparing to other DENV types. DENV-3 takes a longer time to establish and strive in the environment, whereas DENV-1 and DENV-4 are equally competitive and thrive in the environment depending on which serotype infects first. Also the current study findings suggest that a particular DENV infection needs to be present over a period to increase its progeny. When a DENV serotype establishes itself in the experimental environment, the next infecting serotype has to exert pressure to initiate replication.
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    Ethnic tropism of Helicobacter pylori infection towards tamil ethnicity in a Sri Lankan sample
    (University of Peradeniya, 2016-11-05) Buharideen, S.M.; Petangoda, M.A.; Wijetunge, S.; Dissanayake, E.W.N.S.B.; Dayarathne, P.N.D.; Kotakadeniya, R.; Noordeen, F.; Abeykoon, A.M.S.B.
    Some Helicobacter pylori strains are known to demonstrate ethnic tropism, e.g. East Asians are preferentially affected by more virulent strains, whereas, in the rest of Asia and Africa less virulent strains are more prevalent. We conducted the following study to assess the anti H. pylori IgG prevalence patterns in a cohort of symptomatic patients and asymptomatic volunteers. A sample of 460 subjects, 241 symptomatic patients and 219 asymptomatic volunteers, residing in the Central Province were recruited. Sample selection was performed in a randomized manner and the investigators were blind to the ethnicity of the participants. Serum anti H. pylori IgG status was assessed by ELISA (Microtech 07BC1051) in venous blood. Fisher's Exact Test and Jonckheere test were used as the statistical tests. The mean age of the sample was 48.86(SD 14.05) and 246 (53.5%) were males. The ethnic distribution of the sample was 424 (92.2%) Sinhalese, 21 (4.6%) Tamils and 15 (3.2%) Muslims. Among symptomatic patients 9 (3.7%) and asymptomatic volunteers 1 (0.5%) were positive for anti H. pylori IgG. Ethnic distribution of the anti H. pylori IgG sero-prevalence is as follows, Sinhala 4 (0.9%, 4 symptomatic and none among asymptomatic), Tamil 6 (28.6%, 5 symptomatic and 1 asymptomatic) and none among the Muslim ethnic group. The seropositivity (among symptomatic and asymptomatic) across the ethnic groups is statistically significant at 0.05. Post hoc analysis revealed that the ethnic groups Sinhala-Tamil is significantly different. Eight (80%) of the infected were in the 50 to 70 year age group and the rest was in the 30 – 40 year group. There was no significant difference in the sex distribution of the infected individuals. In conclusion, there is a marked predilection of the H. pylori infection towards the Tamil ethnicity, whereas, the prevalence rates among Sinhalese is markedly low. The reason for overall low prevalence of the infection in the sample could be the presence of Sinhala majority in the sample. The infection is predominantly seen in the above 50 year age group.