Determination of cut-off of diagnostic ELISA for Scrub typhus in endemic setup: Central India

Serology remains the mainstay for diagnosis of scrub typhus. In central India, diagnosis of this neglected emerging zoonotic disease suffers due to lack of standardized region-specific cutoff value and diagnostic test. Henceforth, standardized region-specific cutoff value for diagnostic ELISA play a significant role in initial treatment of patients and to differentiate other febrile diseases in endemic setup. A total of 144 patients of all age groups with acute undifferentiated febrile illness patients, forty healthy controls, dengue and chikungunya positive thirty-five samples in each category, respectively were enrolled in the study and subjected to IgM ELISA (InBioS, International, Inc.). Samples showing OD value more than 0.5 in IgM ELISA, were subjected to nested PCR. Both, receiver operating characteristic (ROC) curve and healthy volunteer samples mean with +3 SD were considered to generate region specific cutoff OD value. A total of 48 patients were diagnosed as cases of scrub typhus through IgM ELISA. Out of 48 samples, 30 were positive by nested PCR. The ROC curve analysis revealed a diagnostic ELISA cutoff value of 0.73 with sensitivity and specificity of 95% and 100%, respectively. The cut off arrived from healthy volunteer is mean OD + 3 SD is 0.72. Considering the significance of scrub typhus diagnosis for treatment and to understand disease dynamics in region wise, the cutoff value of >0.72 for diagnostic ELISA for Madhya Pradesh in central India can be used.

Mumps disease outbreak in Davangere district of Karnataka, India

BACKGROUND

Mumps is a vaccine-preventable disease that usually occurs as a parotitis, but it can also lead to several life- threatening complications, including pancreatitis, meningitis and encephalitis.

OBJECTIVE

To determine and diagnosis of mumps disease, which is communicable disease usually affects childrens. Although it is seen worldwide, but outbreaks not common in India.

MATERIALS AND METHODS

Thirty one suspected mumps cases, who presented to the unimmunized population of Chikkahallivana village in Davangere district of Karnataka, India in January 2014, with clinical evidence of fever, cervical lymphadenitis and ear pain, manifest with self-limited uni-or bilateral parotitis. A total of 31 cases consisting of 31 blood and 31 throat swabs were tested for diagnosis of mumps disease.

RESULTS

Of the 31 suspected cases, laboratory results showed 18 positive for mumps IgM antibodies and 7 cases showed presence of mumps virus RNA by RT-PCR using MV specific nested primers. From 31 cases, 5 were positive with both the methods.

CONCLUSION

We confirmed the cases by serological as well as a sensitive RT-nested PCR-based method and sequencing results for the molecular identification of mumps infection. Sequencing results of the SH gene identified outbreak strain as genotype C, which was consistent with other outbreaks in India.

Non-polio Enteroviruses in Karnataka, India: Virological surveillance of acute flaccid paralysis cases (July 1997-2013)

BACKGROUND AND OBJECTIVES

Since 1997 National Institute of Virology, Bangalore Unit involved in WHO's Acute flaccid paralysis paediatric cases surveillance programme to isolate and detect polioviruses. Stool samples yielded not only polioviruses but also Non-Polio enteroviruses. This report is an overview of non-polio Enterovirus (NPEV) epidemiology in Karnataka state, India for the period of 16-years and 6 months from July 1997-2013.

METHODS

A total of 19,410 clinical samples were processed for virus isolation as a part of acute flaccid paralysis (AFP) surveillance for Global Polio Eradication Programme in India at National Polio Laboratory, at Bengaluru. NPEV detection was performed by virus isolation on cell culture according to World Health Organisation recommended protocols.

RESULTS

A total of 4152 NPEV isolates were obtained. The NPEV isolation rate varied from year to year but with a total NPEV rate of 21.39%.

CONCLUSION

A seasonal variation was noted with high transmission period between April and October with peaks in June-July. The male to female ratio was 1:1.2. The isolation of NPEV decreased significantly with the increase in age. Epidemiology of NPEVs from AFP cases in Karnataka is described.

Malsoor virus, a novel bat phlebovirus, is closely related to severe fever with thrombocytopenia syndrome virus and heartland virus

During a survey in the year 2010, a novel phlebovirus was isolated from the Rousettus leschenaultii species of bats in western India. The virus was identified by electron microscopy from infected Vero E6 cells. Phylogenic analysis of the complete genome showed its close relation to severe fever with thrombocytopenia syndrome (SFTS) and Heartland viruses, which makes it imperative to further study its natural ecology and potential as a novel emerging zoonotic virus.

Isolation of a novel adenovirus from Rousettus leschenaultii bats from India

Surveillance work was initiated to study the presence of highly infectious diseases like Ebola-Reston, Marburg, Nipah and other possible viruses that are known to be found in the bat species and responsible for causing diseases in humans. A novel adenovirus was isolated from a common species of fruit bat (Rousettus leschenaultii) captured in Maharashtra State, India. Partial sequence analysis of the DNA polymerase gene shows this isolate to be a newly recognized member of the genus Mastadenovirus (family Adenoviridae), approximately 20% divergent at the nucleotide level from Japanese BatAdV, its closest known relative.

T-cell Epitopes Identified by BALB/c Mice Immunized with Vaccinia Expressing HIV-1 Gag lie within immunodominant Regions Recognized by HIV-infected Indian Patients

BACKGROUND

Human immunodeficiency virus (HIV) antigens from transmitted strains of HIV would prove crucial in vaccine designing for prevention of HIV infection. Immune response generated by Vaccinia construct expressing the HIV-1 gag gene from transmitted Indian HIV-1 subtype C strain (Vgag) in BALB/c mice is reported in the present study along with the identification of epitopes responsible for induction of the immune response.

AIMS

The aim of this study was to determine immune response generated by the constructs in a mouse model and to understand the epitope specificities of the response.

SETTINGS AND DESIGN

This was an observational study carried out in BALB/c mice.

MATERIALS AND METHODS

The immunogenecity of Vgag construct was evaluated in BALB/c mice after multiple immunizations. T-cell response was monitored by the interferon-γ ELISPOT assay using HIV-1 C Gag overlapping peptides and anti-P24 antibodies were estimated by ELISA.

STATISTICAL ANALYSIS USED

Graphpad prism software was used for statistical analysis and for plotting graphs.

RESULTS

IFN-γ-secreting T cells and antibodies were detected against HIV Gag in mice after immunization. Although after repeated immunizations, antibody-mediated immune response increased or remained sustained, the magnitude of IFN-γ-secreting T cell was found to be decreased over time. The Gag peptides recognized by mice were mainly confined to the P24 region and had a considerable overlap with earlier reported immunodominant regions recognized by HIV-infected Indian patients.

CONCLUSION

Vaccinia construct with a gag gene from transmitted HIV-1 virus was found to be immunogenic. The Gag regions identified by mice could have important implications in terms of future HIV vaccine designing.

Immunomodulatory cytokines determine the outcome of Japanese encephalitis virus infection in mice

Japanese encephalitis virus (JEV) induces an acute infection of the central nervous system, the pathogenic mechanism of which is not fully understood. To investigate host response to JEV infection, 14-day-old mice were infected via the extraneural route, which resulted in encephalitis and death. Mice that received JEV immune splenocyte transfer were protected from extraneural JEV infection. Pathology and gene expression profiles were then compared in brains of mice that either succumbed to JEV infection or were protected from infection by JEV immune cell transfer. Mice undergoing progressive JEV infection had increased expression of proinflammatory cytokines, chemokines, and signal transducers associated with the interferon (IFN) pathway. In contrast, mice receiving immune cell transfer had increased production of the Th2 cytokine IL-4, and of IL-10, with subdued expression of IFN-gamma. We observed IL-10 to be an important factor in determining clinical outcome in JEV infection. Data obtained by microarray analysis were further confirmed by quantitative RT-PCR. Together, these data suggest that JEV infection causes an unregulated inflammatory response that can be countered by the expression of immunomodulatory cytokines in mice that survive lethal infection.

A novel type D simian retrovirus naturally infecting the Indian Hanuman langur (Semnopithecus entellus)

As a simian species, the langurs are not known to harbor simian retroviruses, except for one report on a simian Type D endogenous retrovirus from the spectacled langur (Trachypithecus obscurus) from Malaysia. The present report describes for the first time natural infection of the common Hanuman langur (Semnopithecus entellus) from India by a novel simian retrovirus (SRV). The new SRV is phylogenetically related to but distinct from the three molecularly characterized serotypes, SRV 1-3, of the five known serotypes of SRVs, based on sequence analyses from the 3'orf and env regions of the viral genome. The novel SRV isolated from the Indian Hanuman langur is provisionally named SRV-6.

Investigation of buffalopox outbreaks in Maharashtra State during 1992-1996

During 1992-96, outbreaks of buffalopox zoonosis were reported from different villages in Jalgaon, Dhule and Beed districts of Maharashtra State. In humans, pox lesions were observed on the hands whereas in affected buffaloes and cows the lesions were noticed mainly on the teats and udder. Twenty two virus strains were isolated from the skin scabs collected from infected humans and milch animals. Neutralizing antibodies were detected not only in the sera of affected humans but also in their contacts. Detection of antibodies in young individuals from endemic area, who were neither vaccinated for smallpox nor had any contact with buffaloes or history of any poxvirus disease, is suggestive of occurrence of subclinical infection. A few children who had no contact with infected animals also showed clinical manifestations with disseminated lesions on the face, arm and buttocks, and thus suspected to have acquired infection through their infected parents or other family members indicating a possible man to man transmission. Therefore, in the light of discontinuation of smallpox vaccination, buffalopox outbreaks need to be monitored carefully as this may emerge as a serious zoonotic disease in India.

Susceptibility of laboratory-bred rodents to the experimental infection with dengue virus type 2

Various strains of laboratory-bred rodents viz. mice [Swiss, C57BL/6, C3H/Hej, DBA/2, BALB/c, NMRI (nu/nu) and BL6 (nu/nu) and their heterozygous siblings (nu/+)], Mastomys natalensis, Wistar rat, golden hamster and Indian desert gerbil were inoculated intracerebrally (ic) with mouse-adapted dengue virus type 2 (DV-2). The inoculated animals were observed daily for dullness, anorexia, occult blood in faeces, patechial haemorrhages, lacrymation, paralysis, cachexia, death. Necropsied animals were examined for gastrointestinal haemorrhages and lymphadenopathy. The severity of clinical symptoms in various rodents declined as follows: (i) BL6 (nu/nu) mice exhibited most severe manifestation of all the aforementioned symptoms followed by (ii) NMRI (nu/nu), (iii) BL6 (nu/+) (iv) NMRI (nu/+) and C57BL6, (v) DBA, C3H/Hej and BALB/c, and (vi) Swiss. These results indicate that adaptation of DV-2 to the mouse may be an important factor in exaltation of virulence. Interstrain variation in manifestation of symptoms in mice indicates that the susceptibility to DV-2 may be determined by host genetic factors.