Indian Journal of Virology最新文献

Peste des petitis ruminants (PPR) is an economically important endemic viral disease of sheep and goats in India, where several different homologous PPR vaccine candidates have been developed. We evaluated the serological response to two vaccine strains, Arasur/87 and Sungri/96, in South Indian cross-bred and native sheep and goats reared under organized and unorganized settings. Animals seronegative (percent inhibition or PI <40) by competitive enzyme-linked immunosorbent assay (c-ELISA) were immunized with either of the vaccine strains or placebo. Sera collected on 21, 60 and 90 days post-vaccination were subjected to c-ELISA and serum neutralization test (SNT). Seropositivity (PI >40), seroconversion (fourfold increase in SNT titres) and seroprotection (SNT titre of ≥8 deemed to be protective) ranged from 66.7 to 84.0 %, 56.0 to 69.2 %, and 60.0 to 76.0 %, respectively. However, no significant difference was observed between responses to the two vaccine strains. These results support the premise that the two vaccine strains are equally efficacious.

Equine infectious anemia (EIA) is a retroviral infection of horses. Horses infected by EIA virus (EIAV) become inapparent carriers that remain asymptomatic for the remainder of their life span and serve as infection source to other horses. In this study, agar gel immunodiffusion test and ELISA were used to investigate the presence of antibodies to EIAV in equines. A total of 67,042 equine serum samples from 19 states and two union territories were tested during April 1999 to September 2012. The results revealed that none of the animals were positive for antibodies to EIAV from 1999 to December 2009. However, two EIAV sero-positive cases one each from indigenous and thoroughbred equines were detected in 2010 and 2012, respectively. Occurrence of EIA after a long gap of 11 years is indicative of reemergence of EIA in India which warrants concerted efforts in nationwide surveillance and monitoring for detection and elimination of EIAV carrier animals to prevent EIA outbreak.

In view of the outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 virus in poultry in India, its impact on global public health and growing concerns of avian influenza (AI) viruses, surveys in wet poultry markets were conducted in the states of Maharashtra, West Bengal and Jharkhand in India during the period 2009-2012. During these surveys various types of samples from poultry were collected. During outbreaks and surveys in poultry, tracheal swabs (TS), cloacal swabs (CS), poultry drinking water (PDW) samples and fecal samples (FS) are preferred samples for AI diagnosis. The suitability of various types of poultry samples for AI virus isolation was analyzed. The parameters such as availability of specimen, ease of collection, quality of the specimen for the presence of contaminants such as organic debris or solid matter were considered for the analysis. A total of 2,405 samples were collected, which included 1,297 TS, 1,012 CS, 79 PDW, and 17 FS. Out of 2,309 TS and CS samples 1,752 samples were paired samples, collected from 876 birds. All samples were processed for virus isolation and identification. Of the 2,405 samples AI H9N2 was isolated from 199 samples (8.27 %). The virus isolation rate was significantly higher in PDW samples (21.5 %) (P < 0.05) and TS samples (12.1 %), in comparison with CS (2.3 %) (P < 0.001). Other viruses isolated were AI H4N6 and HPAI H5N1viruses; however the number of isolates of AI H4N6 and H5N1 were not sufficient for comparison. In conclusion, the PDW and TS samples were suitable for AI H9N2 virus isolation from poultry.

Bluetongue (BT) is an infectious, arthropod-borne viral disease of domestic and wild ruminants caused by bluetongue virus (BTV), which is a double-stranded segmented RNA virus. Of the 26 confirmed BTV serotypes, 23 were reported in India based on the detection of antibodies or virus. In order to assess the prevalence of different serotypes in Andhra Pradesh, serum samples which were positive for BTV by group-specific antibody ELISA were subjected to type-specific neutralization of BTV serotypes 1, 2, 9, 10, 21 and 23. Of the 52 samples tested, 50.0, 44.23, 21.15, 26.92, 0, and 15.38 % neutralized BTV serotypes 1, 2, 9, 10, 21 and 23, respectively. However, 32.69 % of the ELISA positive sera could not neutralize any of these serotypes, indicating that there could be other serotype viruses (e.g., BTV-3 and -16) circulating in the State. This method can be used for surveillance of the circulating serotypes as well as for assessing the level of herd immunity, and assist in determining the vaccine strains to be used in multivalent vaccines.

Camelpox is considered as emerging public health problem during this decade due to increased reported cases and outbreaks in camels. Camelpox is a contagious, often sporadic, and notifiable skin disease of camelids and is socio-economically significant as it incurs considerable loss in terms of morbidity, mortality, loss of weight and reduction in milk yield and confined to camel-rearing countries. The causative agent, camelpox virus (CMLV) is genetically closely related to variola virus and has gained much attention from researchers due to its recent emergence in human. The virus carrying genes responsible for host immune evasion mechanisms owing to the threat posed by potential bio-warfare agents. Although the disease can be diagnosed based on clinical features, the similar confounding skin lesions necessitate identification, detection and differentiation of the CMLV by molecular techniques. Vaccines are available in some countries and the available live attenuated vaccine provides long-lasting immunity. Further, novel highly sensitive and specific techniques would be useful in the identification of emerging and re-emerging virus, thereby therapeutic, prophylactic, preventive measures would be applied in time to curtail further spread of camelpox like other zoonotic diseases. This review provide overview of the camelpox particularly on its epidemiology, pathogenesis and biology of the disease, diagnostic approaches and control measures.

Several outbreaks of avian influenza (AI) caused by H9N2 subtype, have been reported in the poultry industry during 1990 around the globe. Currently, H9N2 are endemic in the large area of Middle and Far East, including Pakistan. Since H9N2 AI viruses are sporadically reported from humans, extensive incidence of H9N2 in poultry imposes a great risk for human health. In this context, continuous monitoring of the poultry and determining the genetic nature of these viruses are fundamental to predict any future threat. Thus gene sequences of one isolate of H9N2, isolated from commercial poultry flocks, were analyzed. The results of this investigation, based on hemagglutinin (HA), neuraminidase (NA) and non-structural genes, showed that Pakistani H9N2 isolates are closely related to each other and to other H9N2 isolates from the Middle East. However, several unusual substitutions with unknown functional consequences were observed in HA and NA proteins and thus warrant further investigations for their possible role in viral biology. In conclusion, these findings provide information regarding the genetic nature of H9N2 avian influenza viruses in Pakistani poultry and necessitate the sequencing of more H9N2 viruses from both naturally infected and vaccinated flocks.

Equine infectious anemia (EIA)-a retroviral disease caused by equine infectious anemia virus (EIAV)-is a chronic, debilitating disease of horses, mules, and donkeys. EIAV infection has been reported worldwide and is recognized as pathogen of significant economic importance to the horse industry. This disease falls under regulatory control program in many countries including India. Control of EIA is based on identification of inapparent carriers by detection of antibodies to EIAV in serologic tests and "Stamping Out" policy. The current internationally accepted test for diagnosis of EIA is the agar gel immune-diffusion test (AGID), which detects antibodies to the major gag gene (p26) product. The objective of this study was to develop recombinant p26 based in-house immunoassays [enzyme linked immunosorbent assays (ELISA), and AGID] for EIA diagnosis. The synthetic p26 gene of EIAV was expressed in Escherichia coli and diagnostic potential of recombinant p26 protein were evaluated in ELISA and AGID on 7,150 and 1,200 equine serum samples, respectively, and compared with commercial standard AGID kit. The relative sensitivity and specificity of the newly developed ELISA were 100 and 98.6 %, respectively. Whereas, relative sensitivity and specificity of the newly developed AGID were in complete agreement in respect to commercial AGID kit. Here, we have reported the validation of an ELISA and AGID on large number of equine serum samples using recombinant p26 protein produced from synthetic gene which does not require handling of pathogenic EIAV. Since the indigenously developed reagents would be economical than commercial diagnostic kit, the rp26 based-immunoassays could be adopted for the sero-diagnosis and control of EIA in India.

The peptide dendrimer provides novel strategies for various biological applications. Assembling of peptide in macromolecular structure is expected to give rational models as drugs, their delivery and diagnostic reagents. Improved understanding of virus structure and their molecular interactions with ligands have paved the way for treatment and control of emerging and re-emerging viral diseases. This review presents a brief account of a synthetic peptide dendrimer used for diagnostic, therapeutic and prophylactic applications. The designs comprise of multiple antigenic peptides which are being used as alternate synthetic antigens for different viruses.

Genetic and antigenic analysis of H5N1 viruses, isolated in India during a period from year 2006 to 2010, was carried out for selection of the potential H5-HA (haemagglutinin) gene donor virus for developing a reverse genetics based DIVA marker H5 vaccine for poultry in India. Out of the 47 H5N1 viruses (clade 2.2), 14 representative viruses were selected on the basis of amino acid sequence analysis of HA1 gene for further antigenic characterization. Using antigenic cartography, an antigenic map was constructed based on the data of cross-HI (haemagglutinin inhibition) titration of 14 sera versus 14 viruses to visualize the relatedness among the antigens and antigenic coverage of the sera. Sera against five H5N1 viruses (A/crow/Assam/142119/2008, A/chicken/West Bengal/100879/2008, A/chicken/West Bengal/155505/2009, A/chicken/West Bengal/80995/2008 and A/chicken/West Bengal/81760/2008) exhibited maximum (100 %) antigenic coverage, hence, were selected as the potential HA donor viruses. However, the virus strain A/chicken/West Bengal/80995/2008 matched completely with the consensus amino acid sequence of the 47 viruses, therefore, was considered the best HA donor candidate out of the five showing 100 % antigenic coverage. The present study demonstrates a stepwise methodology for logical selection of vaccine strain or HA gene donor strain for developing H5 vaccines using genetic and antigenic data.

The non-structural protein 1 (NS1) of avian influenza virus was defined as one of the virulent factors. To understand the effect of NS1 protein of influenza virus H5N1 isolated in Thailand on type I (α/β) interferon (IFN) synthesis, five reverse genetic viruses were constructed and used as models. The viruses were generated using NS genomic segment from A/Peurto Rico/8/1934 (H1N1) and four avian influenza viruses isolated from the first outbreak in Thailand. All the viruses have the rest of the genome from A/Peurto Rico/8/1934 (H1N1). The constructed viruses were named (1) NS1 PR8/34, (2) NS1 wild type, (3) NS1 L15FD53G, (4) NS1 N171I and (5) NS1 E71K, respectively. The type I (α/β) IFN gene expression in control and infected primary chicken embryonic fibroblast cells were analyzed by quantitative polymerase chain reaction. The results show that the inhibition of IFN-β gene expression by NS1 wild type infected cells is stronger than NS1 N171I, NS1 E71K, NS1 PR8/34 and NS1 L15FD53G, respectively. The data suggest that the difference of amino acid sequence of NS1 protein contributes to the IFN-β antagonist. In contrast, the difference of the NS1 protein does not influence in the IFN-α antagonistic activity.