Point of Care Tuberculosis Sero-Diagnosis Kit for Wild Animals: Combination of Proteins for Improving the Diagnostic Sensitivity and Specificity.

Tuberculosis is a significant problem globally for domestic animals as well as captive and free ranging wild life. Rapid point of care (POC) serology kits are well suited for the diagnosis of TB in wild animals. However, wild animals are invariably exposed to environmental non-pathogenic mycobacterium species with the development of cross reacting antibodies. In the present study, POC TB diagnosis kit was developed using a combination of pathogenic Mycobacteria specific recombinant antigens and purified protein derivatives of pathogenic and non-pathogenic Mycobacteria. To benchmark the TB antibody detection kit, particularly in respect to specificity which could not be determined in wildlife due to the lack of samples from confirmed uninfected animals, we first tested well-characterized sera from 100 M. bovis infected and 100 uninfected cattle. Then we investigated the kit's performance using sera samples from wildlife, namely Sloth Bears (n = 74), Elephants (n = 9), Cervidae (n = 14), Felidae (n = 21), Cape buffalo (n = 2), Wild bear (n = 1) and Wild dog (n = 1).In cattle, a sensitivity of 81% and a specificity of 90% were obtained. The diagnostic sensitivity of the kit was 94% when the kit was tested using known TB positive sloth bear sera samples. 47.4% of the in-contact sloth bears turned seropositive using the rapid POC TB diagnostic kit. Seropositivity in other wild animals was 25% when the sera samples were tested using the kit. A point of care TB sero-diagnostic kit with the combination of proteins was developed and the kit was validated using the sera samples of wild animals.

Direct typing of Canine parvovirus (CPV) from infected dog faeces by rapid mini sequencing technique.

Canine parvovirus (CPV) is a non-enveloped single stranded DNA virus with an icosahedral capsid. Mini-sequencing based CPV typing was developed earlier to detect and differentiate all the CPV types and FPV in a single reaction. This technique was further evaluated in the present study by performing the mini-sequencing directly from fecal samples which avoided tedious virus isolation steps by cell culture system. Fecal swab samples were collected from 84 dogs with enteritis symptoms, suggestive of parvoviral infection from different locations across India. Seventy six of these samples were positive by PCR; the subsequent mini-sequencing reaction typed 74 of them as type 2a virus, and 2 samples as type 2b. Additionally, 25 of the positive samples were typed by cycle sequencing of PCR products. Direct CPV typing from fecal samples using mini-sequencing showed 100% correlation with CPV typing by cycle sequencing. Moreover, CPV typing was achieved by mini-sequencing even with faintly positive PCR amplicons which was not possible by cycle sequencing. Therefore, the mini-sequencing technique is recommended for regular epidemiological follow up of CPV types, since the technique is rapid, highly sensitive and high capacity method for CPV typing.

Rabies virus isolates of India - simultaneous existence of two distinct evolutionary lineages.

Rabies is a fatal viral disease of serious public health implication. The disease is enzootic in India. In the present study, thirty six rabies virus isolates were obtained from terrestrial mammals of India during 2002-2012. Ecto-domain coding region of the glycoprotein gene from all the isolates were sequenced and the phylogenetic analysis was performed in relation to the global rabies and rabies related virus isolates. The Indian isolates grouped into two distinctly separate lineages with majority of the Indian isolates in Arctic like 1 lineage and the remaining isolates in sub-continental lineage. Isolates of the two distinct lineages were identified simultaneously from the same geographical region. Time scaled phylogenetic tree indicated that the sub-continental lineage of the virus is one of the earliest clade of rabies virus that diverged from bat rabies virus. On the contrary, the Arctic-like 1 lineage of India appeared to be a more recent divergence event. The amino acid sequence comparison revealed that all the major antigenic sites were almost conserved among the Indian isolates whereas few amino acid variations could be identified around site IIa, minor site I and IV. The dN/dS study based on G ecto-domain is in support of the earlier reports of strong purifying selection. In conclusion, it is evident that the Indian rabies virus isolates are of two major distinct lineages with distant phylogenetic and evolutionary relationship.

Development of foot-and-mouth disease virus (FMDV) serotype O virus-like-particles (VLPs) vaccine and evaluation of its potency.

Foot-and-mouth disease (FMD) is an economically significant viral disease that rampage dairy and other livestock industries in many countries. The disease is being controlled by the use of an inactivated vaccine. However, a recombinant marker vaccine, which avoids the use of live virus, may be an option for the unambiguous differentiation of infected animals from vaccinated animals. A recombinant baculovirus clone containing P1-2A-3C coding sequences of foot-and-mouth disease virus (FMDV) serotype O(1) Manisa was generated. The FMDV structural proteins along with the 3C protease were expressed in Sf9 cells and the generation of virus like particles (VLP) was studied. The recombinant protein was formulated as vaccine using an oil adjuvant, ISA 206 and potency of the vaccine was tested in cattle. The vaccine had a potency value (PD(50)) of 5.01 and most of the vaccinated animals exhibited neutralizing antibody titers after two immunizations.

Expression and solubilization of insect cell-based rabies virus glycoprotein and assessment of its immunogenicity and protective efficacy in mice.

Rabies is a fatal zoonotic disease of serious public health and economic significance worldwide. The rabies virus glycoprotein (RVG) has been the major target for subunit vaccine development, since it harbors domains responsible for induction of virus-neutralizing antibodies, infectivity, and neurovirulence. The glycoprotein (G) was cloned using the baculovirus expression vector system (BEVS) and expressed in Spodoptera frugiperda (Sf-9) cells. In order to obtain a soluble form of G suitable for experimentation in mice, 18 different combinations of buffers and detergents were evaluated for their ability to solubilize the insect cell membrane-associated G. The combination that involved 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) detergent in lysis buffer 1, formulated with Tris, NaCl, 10% dimethyl sulfoxide (DMSO), and EDTA, gave the highest yield of soluble G, as evidenced by the experimental data. Subsequently, several other parameters, such as the concentration of CHAPS and the duration and temperature of the treatment for the effective solubilization of G, were optimized. The CHAPS detergent, buffered at a concentration of 0.4% to 0.7% (wt/vol) at room temperature (23 to 25°C) for 30 min to 1 h using buffer 1, containing 10% DMSO, resulted in consistently high yields. The G solubilized using CHAPS detergent was found to be immunogenic when tested in mice, as evidenced by high virus-neutralizing antibody titers in sera and 100% protection upon virulent intracerebral challenge with the challenge virus standard (CVS) strain of rabies virus. The results of the mice study indicated that G solubilized with CHAPS detergent retained the immunologically relevant domains in the native conformation, thereby paving the way for producing a cell-free and efficacious subunit vaccine.

Difference in the level of interferon gamma mRNA transcripts on stimulation of cattle and buffalo mononuclear cells with foot and mouth disease virus-antigen: a possible role of sequence variation in promoter region.

In an attempt to resolve the claim that buffaloes differ from cattle in disease progression, this study was undertaken to compare the mitogen (conA) or antigen (foot and mouth disease virus) induced expression levels of interferon gamma (IFN-γ mRNA in peripheral blood mononuclear cells (PBMCs) by real-time quantitative PCR. In general, the levels of IFN-γ mRNA were lower in buffaloes than in crossbred cattle. Significantly higher levels of IFN-γ mRNA were also observed in crossbred cattle when induced with FMD virus (1 µg). Analysis of the partial promoter sequences of the IFN-γ gene from the respective species revealed a conserved 4 base (GTCT) deletion in all the buffalo promoter sequences. In-silico analysis indicated the binding of glucocorticoid receptor (GR) and erythroid nuclear factor (NF-E) to this region in cattle. GR has been shown to be a transcription factor by itself and also regulates other major transcription factors like NF-κB and AP-1. The differential expression levels of IFN-γ mRNA between these species could be due to this deletion in the promoter region of buffalo. Further studies involving mobility shift and promoter assays would throw more light on the differential expression levels.

Analysis of VP2 gene sequences of canine parvovirus isolates in India.

The epidemiology of canine parvovirus (CPV) infections in dogs in India was examined using 27 isolates collected during a two-year period. The VP2 genes of 22 isolates were sequenced, and the deduced amino acid sequences were compared. The results indicated that the isolates belonged to CPV type 2a except four, which belonged to CPV type 2b. Comparison of the VP2 gene sequences revealed that the Indian isolates formed separate lineages distinct from the South East Asian isolates. The canine parvovirus isolates in India appear to evolve independently, and distinct geographical patterns of evolution could not be discerned in the isolates examined.

A simple immuno-capture ELISA to estimate rabies viral glycoprotein antigen in vaccine manufacture.

Rabies is an endemic, fatal zoonotic disease in the developing countries. Prevention and post-exposure therapy require safe and efficacious vaccines. The vaccine potency depends on the amount of immunogenic rabies viral glycoprotein antigen in the vaccine preparation. In order to estimate the rabies viral glycoprotein antigen, a specific monoclonal antibody was developed and used in an immuno-capture ELISA (IC-ELISA). The monoclonal antibody binds a conformational epitope on the natively folded rabies viral glycoprotein as indicated by specific, membrane fluorescence on unfixed, rabies virus infected murine neuroblastoma (MNA) cells and glycoprotein gene encoding plasmid transfected COS cells. In addition, the monoclonal antibody competes with and blocks a glycoprotein antigen site III binding monoclonal antibody (mAb-D1, Institut Pasteur, Paris, France). The monoclonal antibody was used in an IC-ELISA using an in-house standard to quantify the rabies viral glycoprotein antigen in 12 vaccine preparations with potency values ranging from 4 to 18 IU. The results indicated a good correlation with the NIH mouse potency assay (r=0.83). The immuno-capture ELISA described in this study can be used to quantify the immunogenic rabies viral glycoprotein antigen in the inactivated rabies viral antigen preparation in a simple and rapid format, which enables better vaccine formulation.