Desh Deepak Singh

Co-positivity of anti-dengue virus and anti-Japanese encephalitis virus IgM in endemic area: co-infection or cross reactivity?

OBJECTIVE To report high co-positivity of anti-dengue virus (DV) and anti-Japanese encephalitis virus (JEV) IgM in an area endemic for both the viruses and to discuss the possibilities of co-infection. METHODS Serum samples from the patients who presented with fever, suspected central nervous system infection and thrombocytopenia, were tested for anti-DV IgM and anti-JEV IgM antibodies. Conventional reverse transcriptase polymerase chain reaction was done for detection of DV RNA and JEV RNA. RESULTS Of 1 410 patient sera tested for anti-DV and anti-JEV antibodies, 129 (9.14%) were co-positive for both. This co-positivity was observed only in those months when anti-JEV IgM positivity was high. Titers of both anti-DV IgM and anti-JEV IgM were high in most of the co-positive cases. Among these 129 co-positive cases, 76 were tested by conventional reverse transcriptase polymerase chain reaction for both flaviviruses, of which eight cases were co-positive for DV and JEV. CONCLUSIONS Co-infection with more than one flavivirus species can occur in hyperendemic areas.

Prevalence and genotypic characterization of human parvovirus B19 in children with hemato‐oncological disorders in North India

Human parvovirus B19 (B19V) has been associated with chronic anemia in immuno‐compromised patients. In the present study, the prevalence and genotype distribution of B19V in children from North India, suffering with hemato‐oncological disorders is reported. Children with aplastic anemia/leukemia/chronic hematological disorders, and healthy blood donors were enrolled in the study. Blood samples from cases and blood donors were analyzed for anti‐B19V IgM and anti‐B19V IgG antibodies by ELISA and for B19V‐DNA by PCR. B19V‐DNA positive samples were studied further for determination of viral load in samples and for B19V‐DNA sequence (VP1/VP2 overlapping region) analysis. Total 238 cases (103 leukemia, 77 aplastic anemia and 58 chronic hematological disorders) and 350 blood donors were enrolled in the study. Anti‐B19V IgM was positive in 16 (6.7%) cases, B19V‐DNA was detected in 13 (5.5%) cases and anti‐B19V IgG was positive in 127 (53.4%) cases. Total 223 (63.5%) blood donors were positive for anti‐B19V IgG, however, anti‐B19V IgM and B19V‐DNA was not detected in any blood donor. The prevalence of anti‐B19V IgG was significantly higher in children > 10 years of age. Viral load of B19V decreased with appearance of specific antibodies. Phylogenetic analysis of the VP1/VP2 overlapping region revealed that genotype 1 predominated in these patients (11/13, 84.6%), followed by genotype 3 (2/13, 15.4%). No genotype 2 was detected. All the genotype 1strains were sub‐typed as 1a, except four strains, which matched neither 1a nor 1b and formed a separate cluster. Both the genotype 3 strains were sub‐typed as 3b. J. Med. Virol. 87:303–309, 2015.

Multipurpose Instantaneous Microarray Detection of Acute Encephalitis Causing Viruses and Their Expression Profiles

Detection of multiple viruses is important for global analysis of gene or protein content and expression, opening up new prospects in terms of molecular and physiological systems for pathogenic diagnosis. Early diagnosis is crucial for disease treatment and control as it reduces inappropriate use of antiviral therapy and focuses surveillance activity. This requires the ability to detect and accurately diagnose infection at or close to the source/outbreak with minimum delay and the need for specific, accessible point-of-care diagnosis able to distinguish causative viruses and their subtypes. None of the available viral diagnostic assays combine a point-of-care format with the complex capability to identify a large range of human and animal viruses. Microarray detection provides a useful, labor-saving tool for detection of multiple viruses with several advantages, such as convenience and prevention of cross-contamination of polymerase chain reaction (PCR) products, which is of foremost importance in such applications. Recently, real-time PCR assays with the ability to confirm the amplification product and quantitate the target concentration have been developed. Furthermore, nucleotide sequence analysis of amplification products has facilitated epidemiological studies of infectious disease outbreaks and monitoring of treatment outcomes for infections, in particular for viruses that mutate at high frequency. This review discusses applications of microarray technology as a potential new tool for detection and identification of acute encephalitis-causing viruses in human serum, plasma, and cell cultures.

Observation on dengue cases from a virus diagnostic laboratory of a tertiary care hospital in North India

Background & objectives: The epidemiology of dengue fever (DF) is complex in the Indian subcontinent as all the four serotypes are circulating. This study reports observations on dengue cases from a virus diagnostic laboratory of a north Indian tertiary care hospital catering to areas in and around Lucknow, Uttar Pradesh. Methods: Serum samples were obtained from suspected cases of dengue referred to the virus diagnostic laboratory during 2011 to 2013, and detailed history was taken on a pre-structured datasheet. All samples were tested for anti-dengue virus (DV) IgM antibodies and DV-non structural protein 1 antigen (NS1Ag) by ELISA. NS1Ag positive samples were tested further by conventional RT-PCR for DV-RNA detection and serotyping. Results: Of the 4019 suspected patients of dengue, 886 (22%) showed laboratory evidence of dengue virus infection. Of these, 19, 17 and 27 per cent were positive in 2011, 2012 and 2013, respectively. Children and adults were similarly affected by dengue in all the three years. Males were more commonly affected than females. The predominant DV serotype detected was DV-2, DV-1 and DV-3 in 2011, 2012 and 2013, respectively. DV-4 serotype was not detected. About half the cases positive for DV infection, showed symptoms of dengue with warning signs/severe dengue. A distinct seasonality with increase in number of dengue cases in the post monsoon period was seen. Interpretation & conclusions: Change in circulating serotype of dengue virus; a distinct adult dengue involvement; and a remarkable number of cases presenting with severe dengue manifestations are the main findings of this study.