Acta Biomedica Scientia

A STUDY ON IDENTIFICATION OF CIRCULATION OF DENGUE VIRUS SEROTYPES IN THE CITY OF HYDERABAD, TELANGANA AS DETERMINED BY CONVENTIONAL REVERSE TRANSCRIPTION POLYMERASE CHAIN REACTION

G.Sushma Rajya Lakshmi*, DR.Manisha Rani, K.Nagamani, K.NagaSoujanya, Sunitha Pakalapaty, Swathi Akula

sushmy.rl@gmail.com

Dengue, Epidemic, Serotypes, Polymerase Chain Reaction.

The present study was aimed to investigate the circulation of dengue virus (DENV) serotypes in Hyderabad. Hyderabad a city in South India, has so far witnessed several reported outbreaks of dengue. Dengue in Hyderabad from being epidemic is slowly changing towards being endemic and hyper-endemic. Circulating type of the virus is also changing over the years. In the absence of an effective vaccine, dengue prevention to a major extent relies on virological surveillance and development of effective, locally adapted control programmes. In the present study, we tried to identify the between-year non-epidemic serotype of dengue virus circulating in Hyderabad during 2014–15.Acute-phase samples were collected from the patients attending the Gandhi Hospital, Hyderabad, Telangana, India. Dengue diagnosis was done using WHO case definitions. In the present study,119 serum samples were randomly selected and subjected to Dengue NS1 Ag ELISA, IgM ELISA and multiplex nested RT-PCR. Among 119 samples screened, 16 were positive only for NS1 antigen ELISA, 55 were positive for both NS1 antigen and Ig M ELISA and 48 were positive only for Ig M ELISA. Out of the 16 cases positive for only NS1 antigen ELISA, 8 were positive by PCR, among the 55 cases that were positive for both NS1 antigen ELISA and Ig M ELISA, 20 were positive by PCR, and among the 48 cases positive only for Ig M ELISA, 1 was positive by PCR. The sensitivity of NS1 Ag was 97.26 % and sensitivity of multiplex RT-PCR was 40.27 %, while specificity for both was 100 %.Of th119 samples, only 29 samples were found to be positive for dengue virus infection by PCR. RT-PCR could detect the virus in serum samples collected before 8 days of illness. The predominant serotype in the year 2014 and 2015 was DENV 1 serotype followed by DENV 3 serotype. However only 23 cases in 2014 and 96 cases in 2015 were subjected to RT PCR which was not sufficient enough for comparison of the serotypes for both the years. DENV1 serotype was found to have more haemorrhagic manifestations (57.6%) than DENV 3 serotype (33.33%). To the best of knowledge, the current study demonstrated the prevalence of the DENV-1 serotype in the Hyderabad city in Telangana, India. Infection with one dengue virus serotype may provide lifelong Immunity against that particular virus serotype but it may confer only partial and transient protection against subsequent infection by the other three serotypes of the virus and sometimes sequential infection may increase the risk of developing severe dengue infection due to cross reactive T cells. Thus serotyping might be helpful in predicting the severity of infection as well as for further management and prevention of the disease. The implementation of this assay in dengue-endemic areas has the potential to improve both dengue diagnosis and epidemiologic surveillance.