Assessment of post-vaccination immune response to peste des petits ruminants virus in small ruminants in the central and western regions of India

The cross-sectional serosurvey for post-vaccination assessment of peste des petits ruminants (PPR) virus (PPRV) antibodies in sheep and goats was carried out in different states in the central and western regions of India after the implementation of vaccination under the PPR control programme. The serum samples (n = 4687) were collected from sheep (n = 1539) and goats (n = 3148) from August 2017 to March 2018 at various epidemiological units (n = 301) of the studied regions using a stratified random sampling method and PPR competitive ELISA kit was employed to detect PPRV antibodies. The results revealed 34, 21, 52, 74, 68, and 65% of prevalence of PPRV antibodies in small ruminants in Madhya Pradesh, Goa, Chhattisgarh, Maharashtra, Gujarat, and Rajasthan states, respectively, with a difference in seropositivity in sheep and goats across the states in sheep (p < 0.01) and goats (p < 0.01). Further, this serosurvey revealed that 60% of the epi-units (n = 185) had > 50% prevalence of post vaccination PPRV antibodies across states due to variations in vaccination rates and patterns. The vaccination coverage and the reported outbreaks varied between the states in the studied regions. Due to continuous vaccination under the control program, the reported PPR outbreaks have progressively declined in most of the studied states, and the PPR risk areas are confined to a few districts and sporadically, outbreaks are reported indicating the effectiveness of vaccination. These findings provide valuable information on potential PPRV episystems, and will assist with activities regarding intensive surveillance, vaccination, biosecurity, and modification of policy decisions towards designing and implementing control and eradication measures. Further, the present situation necessitates continuous mass vaccination and active surveillance programs to make these regions free from PPR in consonance with the PPR Global Control and Eradication Strategy under the PPR Global Eradication Program.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-022-00796-6.

Differential expression of long non-coding RNAs under Peste des petits ruminants virus (PPRV) infection in goats

Peste des petits ruminants (PPR) characterized by fever, sore mouth, conjunctivitis, gastroenteritis, and pneumonia, is an acute, highly contagious viral disease of sheep and goats. The role of long non-coding RNAs (lncRNAs) in PPRV infection has not been explored to date. In this study, the transcriptome profiles of virulent Peste des petits ruminants virus (PPRV) infected goat tissues – lung and spleen were analyzed to identify the role of lncRNAs in PPRV infection. A total of 13,928 lncRNA transcripts were identified, out of which 170 were known lncRNAs. Intergenic lncRNAs (7625) formed the major chunk of the novel lncRNA transcripts. Differential expression analysis revealed that 15 lncRNAs (11 downregulated and 4 upregulated) in the PPRV infected spleen samples and 16 lncRNAs (13 downregulated and 3 upregulated) in PPRV infected lung samples were differentially expressed as compared to control. The differentially expressed lncRNAs (DElncRNAs) possibly regulate various immunological processes related to natural killer cell activation, antigen processing and presentation, and B cell activity, by regulating the expression of mRNAs through the cis- or trans-regulatory mechanism. Functional enrichment analysis of differentially expressed mRNAs (DEmRNAs) revealed enrichment of immune pathways and biological processes in concordance with the pathways in which correlated lncRNA-neighboring genes were enriched. The results suggest that a coordinated immune response is raised in both lung and spleen tissues of the goat through mRNA-lncRNA crosstalk.

Avidin-Biotin recombinant nucleoprotein competitive ELISA for the detection of peste des petits ruminants virus antibodies in sheep and goats

The present study describes the development of a truncated recombinant peste des petits ruminants virus (PPRV) nucleoprotein (rPPRV-NPN) and its polyclonal antibodies-based immuno-diagnostic assay, Avidin-Biotin (AB) recombinant nucleoprotein competitive ELISA (ABrC-ELISA) for the detection of PPRV antibodies in the sheep and goats. The PPRV N-terminal immunogenic region (1-266 aa) of nucleoprotein (NPN) coding sequence was amplified and cloned into the pETite vector. The rPPRV-NPN with a molecular weight of ∼ 30 kDa was expressed in E. coli, purified, and characterized by SDS-PAGE and immunoblot using standard PPRV specific sera. The Ni-NTA affinity-purified rPPRV-NPN as coating antigen and its hyperimmune serum as competitive antibodies raised in guinea pigs were evaluated as diagnostic reagents in ABrC-ELISA using the known standard panel of sera. The threshold (cut-off) Percentage Inhibition (PI) value was determined as 45 (mean ± 3 SD) based on the reactivity of the known sheep and goats sera to PPRV antibodies [negative (n = 140) and positive (n = 98)] and the assay had a sensitivity of 97 % (95 % Confidence Interval (CI): 91.3-99.4 %) and specificity of 100 % (95 % CI: 97.4-100 %) with an excellent Area under curve (AUC) of 0.997 (95 % CI: 0.99-1.0). On evaluation of diagnostic performance of the assay using the sheep and goats sera (n = 391) from vaccinated, infected, and non-vaccinated animals, the ABrC-ELISA showed the relative diagnostic sensitivity of 95.88 % (95 % CI: 92.56-98.01 %) & 98.77 % (95 % CI: 96.43-99.74 %) and diagnostic specificity of 97.97 % (95 % CI: 94.19-99.58 %) & 90.54 % (95 % CI: 84.64-94.73 %) against indigenous PPR competitive ELISA kit & IDvet Screen® PPR Competition kit, respectively. The study showed that ABrC-ELISA is rapid, sensitive, and specific and can be a better alternative assay for the detection of the PPRV antibodies in the sera of small ruminants for serosurveillance / seromonitoring of PPR not only at the eradication and post-eradication phases in the disease-controlled endemic countries but also in the PPR non-endemic countries.

Avidin-Biotin recombinant antigen capture ELISA for the detection of peste des petits ruminants virus in the clinical specimens of sheep and goats

This study describes the development of Avidin-Biotin recombinant Antigen Capture ELISA (ABrAC ELISA) for the detection of the peste des petits ruminants virus (PPRV) antigens in the clinical specimens of sheep and goats. The assay uses the truncated recombinant PPRV N-terminal immunogenic region of nucleoprotein (rPPRV-NPN) as a reference positive antigen and its polyclonal antibodies as capture/detective antibodies and the rabbit PPRV polyclonal antibodies as coating antibodies. The cut-off value was determined as double times the mean reactivity of blank control based on the reactivity of the PPR confirmed negative and positive control panel samples. On assessing the specificity with the related differential diagnosis of the disease-causing viruses and bacteria, the assay showed specific detective reactivity to PPRV. Further, on evaluation using clinical specimens (n-274) of sheep and goats, the assay showed that the relative diagnostic sensitivity of 86.49 % (95 % confidence interval (CI): 71.23-95.46 %) and diagnostic specificity of 96.20 % (95 % CI: 92.91-98.25 %) against PPRV nucleoprotein-specific monoclonal antibody-based sandwich-ELISA (PPR s-ELISA) kit, with an accuracy of 94.89 % (95 % CI: 91.58-97.18 %) and Cohen's Kappa value of 0.791 + 0.055 SE (95 % CI: 0.68-0.90) with substantial agreements. The ABrAC-ELISA is an alternative method of an immunoassay for the rapid, sensitive, and specific detection of the PPRV antigens m the clinical specimens of sheep and goats for surveillance or diagnosis of PPR. This study also shows that the rPPRV-NPN and its specific polyclonal antibodies could be the sustainable source of safe diagnostic reagents without the need to handle the infectious virus during the eradication and post-eradication phases in endemic countries like India or PPR non-endemic countries.

Towards eradication of peste des petits ruminants: post-vaccination evaluation in sheep and goats in Southern Peninsular India

The cross-sectional seroprevalence study of the peste des petits ruminants (PPR) in sheep and goats was carried out in the Southern Peninsular region of India to ascertain the prevalence of PPR virus (PPRV) antibodies at the epidemiological units (epi-units) level in the small ruminant population. The serum samples were collected from various epi-units (villages) in the different states and union territory (UT) in Southern Peninsular region using a stratified random sampling methodology from August 2017 to March 2018. A total of 6643 serum samples [sheep (n = 2785) and goats (n = 3858)] were collected from 360 epi-units and were screened by PPR competitive ELISA kit for the detection of PPRV antibodies. The results revealed that the seroprevalence of PPR in small ruminants in Telangana, Andhra Pradesh, Karnataka, Tamil Nadu, and Kerala states, and Puducherry UT was 87.0%, 66.4%, 64.3%, 47.8%, 11.4%, and 50.4%, respectively in the studied region. Further, the results of the chi-squared test revealed that the PPRV antibodies across different states and UT in the region were associated (sheep-χ² = 218.8, p < 0.01; goats-χ² = 827.1, p < 0.01), as all the states and UT adopted the PPR vaccination programme. The study also implies that the small ruminants in some of the epi-units (n = 102) had < 30% seroprevalence, which necessitates comprehensive intensive vaccination and active surveillance programmes to make this region as PPR free zone.

Seroprevalence of Peste des petits ruminants in small ruminants in the North Eastern Region of India

A seroprevalence study of the peste des petits ruminants (PPR) in small ruminants was carried out in the different states (Assam, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura) in the North Eastern Region (NER) of India using serum samples collected from April 2017 to March 2018. A total number of 4,163 sera [sheep (n = 508) and goats (n = 3,655)] collected from 345 epi‑units/villages covering 176 municipalities in NER were screened by competitive ELISA kit for the detection of PPR virus antibodies. The results revealed that the seroprevalence of PPR in small ruminants in Assam, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura was 34.3%, 10.3%, 4.7%, 15.7%, 14.7%, and 5.5%, respectively with an overall 14.5% prevalence.Association between the presence of antibodies and goats has been showed to be significant (p < 0.01) at the NER level level and within every single state. This manuscript highlights the need for continuous monitoring of this important disease as for the severe economic impact PPR may have in the affected countries.

Contrasting Gene Expression Profiles of Monocytes and Lymphocytes From Peste-Des-Petits-Ruminants Virus Infected Goats

In this study, transcriptome analysis of PPRV infected PBMC subsets-T helper cells, T cytotoxic cells, monocytes, and B lymphocytes was done to delineate their role in host response. PPRV was found to infect lymphocytes and not monocytes. The established receptor for PPRV-SLAM was found downregulated in lymphocytes and non-differentially expressed in monocytes. A profound deviation in the global gene expression profile with a large number of unique upregulated genes (851) and downregulated genes (605) was observed in monocytes in comparison to lymphocytes. ISGs-ISG15, Mx1, Mx2, RSAD2, IFIT3, and IFIT5 that play a role in antiviral response and the genes for viral sensors-MDA5, LGP2, and RIG1, were found to be upregulated in lymphocytes and downregulated in monocytes. The transcription factors-IRF-7 and STAT-1 that regulate expression of most of the ISGs were found activated in lymphocytes and not in monocytes. Interferon signaling pathway and RIG1 like receptor signaling pathway were found activated in lymphocytes and not in monocytes. This contrast in gene expression profiles and signaling pathways indicated the predominant role of lymphocytes in generating the antiviral response against PPRV in goats, thus, giving us new insights into host response to PPRV.

Phylogenetic analysis of haemagglutinin gene deciphering a new genetically distinct lineage of canine distemper virus circulating among domestic dogs in India

Canine distemper (CD) is one of the highly contagious and invariably fatal viral diseases of dogs and other carnivores. Despite the widespread use of modified live vaccines to control CD, the prevalence of disease has increased at an alarming rate in recent years. Although a number of factors may be ascribed for vaccine failure, antigenic differences among the vaccine and wild-type strains have gained the interest of researchers. Considering the high genetic variability of haemagglutinin gene (H gene) and its role in eliciting the immune response to canine distemper virus (CDV), we have generated nine full-length CDV H gene sequences from infected dogs including three vaccinated cases. Bayesian analysis was performed using 102 full-length H gene nucleotide sequences over a time frame of 76 years (1940-2016) from 18 countries. The time to the most recent common ancestor (tMRCA) of CDV was estimated to be 1696 AD. Phylogenetic reconstruction clustered Indian wild-type viruses into a distinct monophyletic group clearly separated from the previously established CDV lineages. This signifies the presence of a novel genetic variant (proposed as "Lineage India-1/Asia-5") circulating among dog population in India. To investigate the importance of substitutions at amino acid residues 530 and 549 of CDV H protein in determining the host switches from canid to non-canid hosts, we analysed 125 H gene sequences including nine sequences generated in this study. Selection pressure analysis and analysis of amino acid sequences revealed a trend towards adaptation of 549H variants in non-canid hosts although no role of G/E530R/D/N substitution could be identified. This is the first comprehensive study about the nature and ecology of CDV circulating among dog population in India. Outbreaks in vaccinated animals as observed in this study have raised a concern towards the effectiveness of current vaccine strains warranting detailed investigation.

Dysregulated miRNAome and Proteome of PPRV Infected Goat PBMCs Reveal a Coordinated Immune Response

In this study, the miRNAome and proteome of virulent Peste des petits ruminants virus (PPRV) infected goat peripheral blood mononuclear cells (PBMCs) were analyzed. The identified differentially expressed miRNAs (DEmiRNAs) were found to govern genes that modulate immune response based on the proteome data. The top 10 significantly enriched immune response processes were found to be governed by 98 genes. The top 10 DEmiRNAs governing these 98 genes were identified based on the number of genes governed by them. Out of these 10 DEmiRNAs, 7 were upregulated, and 3 were downregulated. These include miR-664, miR-2311, miR-2897, miR-484, miR-2440, miR-3533, miR-574, miR-210, miR-21-5p, and miR-30. miR-664 and miR-484 with proviral and antiviral activities, respectively, were upregulated in PPRV infected PBMCs. miR-210 that inhibits apoptosis was downregulated. miR-21-5p that decreases the sensitivity of cells to the antiviral activity of IFNs and miR-30b that inhibits antigen processing and presentation by primary macrophages were downregulated, indicative of a strong host response to PPRV infection. miR-21-5p was found to be inhibited on IPA upstream regulatory analysis of RNA-sequencing data. This miRNA that was also highly downregulated and was found to govern 16 immune response genes in the proteome data was selected for functional validation vis-a-vis TGFBR2 (TGF-beta receptor type-2). TGFBR2 that regulates cell differentiation and is involved in several immune response pathways was found to be governed by most of the identified immune modulating DEmiRNAs. The decreased luciferase activity in Dual Luciferase Reporter Assay indicated specific binding of miR-21-5p and miR-484 to their target thus establishing specific binding of the miRNAs to their targets.This is the first report on the miRNAome and proteome of virulent PPRV infected goat PBMCs.

Molecular evidence and phylogenetic analysis of orf virus isolates from outbreaks in Tripura state of North-East India

This study describes the first confirmed report of contagious ecthyma in Black Bengal goats from Tripura state, a North-Eastern state of India situated at the Indo-Bangladesh border. Outbreaks were characterized by the high rates of morbidity (58-67%), low mortality (8-10%) and case fatality (11-15%). The etiology of the outbreaks was confirmed as orf virus (ORFV) by standard virological/serological and molecular techniques including sequence analysis of B2L, a major envelop protein gene of genus Parapoxvirus. Sequence and phylogenetic analysis based on B2L gene of ORFV isolates from Tripura revealed that they were closely related to each other and also to other Indian isolates, in particular to ORFV-Shahjahanpur 82/04 isolate from North India. They revealed several specific nucleotide/amino acid substitutions, namely G299A (G100D), G660A, C705T, C795T (N267D) and G872A (R291H) which may be of notable epidemiological significance. This report necessitates the systematic investigation of orf outbreaks in susceptible populations including wild species particularly at transboundary regions by use of rapid diagnostics to control the infection by deploying an effective vaccine/therapeutics and better managemental practices.

Expression kinetics of ISG15, IRF3, IFNγ, IL10, IL2 and IL4 genes vis-a-vis virus shedding, tissue tropism and antibody dynamics in PPRV vaccinated, challenged, infected sheep and goats

Here, we studied the in vivo expression of Th1 (IL2 and IFN gamma) and Th2 (IL4 and IL10) - cytokines and antiviral molecules - IRF3 and ISG15 in peripheral blood mononuclear cells in relation to antigen and antibody dynamics under Peste des petits ruminants virus (PPRV) vaccination, infection and challenge in both sheep and goats. Vaccinated goats were seropositive by 9 days post vaccination (dpv) while in sheep idiosyncratic response was observed between 9 and 14 dpv for different animals. Expression of PPRV N gene was not detected in PBMCs of vaccinated and vaccinated challenged groups of both species, but was detected in unvaccinated infected PBMCs at 9 and 14 days post infection. The higher viral load at 9 dpi coincided with the peak clinical signs of the disease. The peak in viral replication at 9 dpi correlated with significant expression of antiviral molecules IRF3, ISG15 and IFN gamma in both the species. With the progression of disease, the decrease in N gene expression also correlated with the decrease in expression of IRF3, ISG15 and IFN gamma. In the unvaccinated infected animals ISG15, IRF3, IFN gamma and IL10 expression was higher than vaccinated animals. The IFN gamma expression predominated over IL4 in both vaccinated and infected animals with the infected exhibiting a stronger Th1 response. The persistent upregulation of this antiviral molecular signature - ISG15 and IRF3 even after 2 weeks post vaccination, presumably reflects the ongoing stimulation of innate immune cells.

Modulation of Host miRNAs Transcriptome in Lung and Spleen of Peste des Petits Ruminants Virus Infected Sheep and Goats

Peste des petits ruminants (PPR) is one of the highly contagious viral disease, characterized by fever, sore mouth, conjunctivitis, gastroenteritis, and pneumonia, primarily affecting sheep and goats. Reports suggested variable host response in goats and sheep and this host response vis-a-vis the expression of microRNAs (miRNAs) has not been investigated. Here, miRNAs were sequenced and proteomics data were generated to identify the role of differentially expressed miRNA (DEmiRNA) in PPR virus (PPRV) infected lung and spleen tissues of sheep and goats. In lungs, 67 and 37 DEmiRNAs have been identified in goats and sheep, respectively. Similarly, in spleen, 50 and 56 DEmiRNAs were identified in goats and sheep, respectively. A total of 20 and 11 miRNAs were found to be common differentially expressed in both the species in PPRV infected spleen and lung, respectively. Six DEmiRNAs—miR-21-3p, miR-1246, miR-27a-5p, miR-760-3p, miR-320a, and miR-363 were selected based on their role in viral infections, apoptosis, and fold change. The target prediction analysis of these six selected DEmiRNAs from the proteome data generated, revealed involvement of more number of genes in lung and spleen of goats than in sheep. On gene ontology analysis of host target genes these DEmiRNAs were found to regulate several immune response signaling pathways. It was observed that the pathways viz. T cell receptor signaling, Rap1 signaling, Toll-like receptor signaling, and B cell receptor signaling governed by DEmiRNAs were more perturbed in goats than in sheep. The data suggests that PPRV-induced miR-21-3p, miR-320a, and miR-363 might act cooperatively to enhance viral pathogenesis in the lung and spleen of sheep by downregulating several immune response genes. The study gives an important insight into the molecular pathogenesis of PPR by identifying that the PPRV—Izatnagar/94 isolate elicits a strong host response in goats than in sheep.

Peste des petits ruminants

Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants.

Characterization of cytopathogenicity of classical swine fever virus isolate induced by Newcastle disease virus

Classical swine fever virus (CSFV), the causative agent of classical swine fever, belongs to the family Flaviviridae and genus Pestivirus. Some pestiviruses exhibit cytopathic effect in cell culture but exact phenomenon is unknown. Over expression of NS2-3 gene, presence of defective interfering particle and exaltation of Newcastle disease virus (END) phenomenon could be the reasons of cytopathogenicity. In the present study, a CSFV isolate exhibiting cytopathic effect (CPE) in Madin-Darby Canine Kidney (MDCK) cell line was characterized. To characterize cytopathogenicity of such isolate, END test was carried out. Interference of Newcastle disease virus (NDV) in MDCK adapted CSFV was confirmed by RT-PCR and virus neutralization test. Absence of CPE and NDV specific nucleic acid after neutralization confirmed the induction of CPE by NDV. Further, identity of the CSFV isolate in MDCK cell line by immunoperoxidase test, immunoblotting and RT-PCR post NDV neutralization established the virus replication without CPE (non-cytopathic isolate). Findings suggest that, there could be a chance of mixed infection of both CSFV and NDV in the piglet from which the sample was collected for virus isolation.

Prevalence of classical swine fever virus in India: a 6-year study (2004-2010)

A study was undertaken regarding the prevalence of classical swine fever virus (CSFV) antibodies and antigens in sera and suspected tissue samples of domestic pigs. The samples were received between January 2004 and September 2010. A total of 594 serum samples from 12 states and 287 tissue samples from 13 states of India were tested using commercial enzyme-linked immunosorbent assay (ELISA) kits. The mean prevalence of CSFV antibodies in suspected sera was 63.3% (376/594), whereas 76.7% (220/287) of the suspected samples were found to contain CSFV antigen. The high prevalence of CSFV antibodies suggests that the disease is endemic in the country. This baseline data will be of use in the formulation of control and eradication programmes.

Sequence analysis of the nucleoprotein gene of Asian lineage peste des petits ruminants vaccine virus

The complete nucleotide sequence of the nucleocapsid (N) protein of the peste-des-petits ruminants vaccine virus (PPRV Sungri/96) belonging to the Asian lineage was determined. The gene was 1692 nucleotides in length and encoded a polypeptide of 525 amino acids. The PPRV Sungri/96 N gene has a nucleotide homology of 92% for PPRV Nigeria 75/1 to 55.5% for canine distemper virus. At amino acid level the homology was 94.1% with PPRV Nigeria 75/1, while with other morbilliviruses, PPRV Sungri/96 had only 71.4-64.9% amino acid identity. The phosphorylation prediction reveals eight conserved sites across morbilliviruses, whereas in the C-terminal portion of the protein the sites are not conserved. Phylogenetic analysis of different N proteins of morbilliviruses revealed five well-defined clusters as observed previously. To the best of our knowledge this is the first report describing the nucleocapsid gene sequence of PPRV Indian isolate.

Sequence analysis of the haemagglutinin and fusion protein genes of peste-des-petits ruminants vaccine virus of Indian origin

The amino acid composition of the two surface proteins of peste-des-petits ruminants vaccine virus belonging to lineage four from India were deduced from the nucleotide sequence. The fusion (F) protein gene of PPRV Sungri/96 is 2405 nucleotides long and in relation to the length, it is 80 nucleotides longer than that of PPRV Nigeria/75/1 which are found to be present at the 5'UTR of this virus. The complete F gene alignment with other morbillivirus reveals a homology of 89% with PPRV/Nigeria/75/1 and 48-51% with other morbilliviruses. The F protein of PPRV Sungri/96 exhibited characteristics similarity to those of other morbillivirus F proteins. The overall amino acid similarity with its counterpart PPRV Nigeria/75/1 was 96%; with other morbilliviruses it is 65-74%. The PPRV Sungri/96 haemagglutinin (H) protein gene is 1954 nucleotides long and showed a sequence homology of 90.7% with PPRV/Nigeria/75/1 and with other morbilliviruses it ranged from 33% to 45%. At amino acids level, PPRV Sungri/96 showed a homology of 92.3% with PPRV/Nigeria/75/1 and 34-49% with other morbilliviruses. The phylogenetic tree constructed for F and H gene reveals four separate groups which is very similar to that found in other genes. To the best of our knowledge this is the first report describing the F and H genes of an Indian isolate.

Analysis of the matrix protein gene sequence of the Asian lineage of peste-des-petits ruminants vaccine virus

The M gene nucleotide sequence of an Indian peste-des-petits ruminants (PPRV) vaccine virus ("PPRV Sungri/96") belonging to Asian lineage was determined. The gene is 1476 nucleotides long with a single open reading frame (ORF). The nucleotide and predicted amino acid sequence was compared with the homologous region of the African Lineage Vaccine virus "PPRV/Nigeria/75/1". The nucleotide sequence of the "PPRV Sungri/96" was 86% identical to that of "PPRV/Nigeria/75/1", while a homology of 93% and 95% could be observed in the ORF and amino acids level, respectively. The M gene encodes a protein of 335 amino acids, with a predicted molecular weight (MW) of 37.8 kDa. The ORF is flanked by a 3' untranslated region of 436 nucleotides and a high level of sequence divergence (approximately 30%) could be observed in this region between the vaccine viruses of Asian and African lineages. A high degree of conservation of several amino acids of this protein observed previously was also confirmed in this study.

Comparative nucleotide sequence analysis of the phosphoprotein gene of peste des petits ruminants vaccine virus of Indian origin

The nucleotide sequences of the phosphoprotein (P) gene of peste des petits ruminants (PPRV) vaccine virus (PPRV Sungri/96) belongs to Asian lineage have been determined and the deduced amino acid sequences were compared with another vaccine strain PPRV/Nigeria75/1 and with those of the other morbilliviruses. The 1652 nucleotides of the P gene encode a phosphoprotein of 509 amino acid residues (from nucleotide numbers 60 to 1587), which is 91% identical to that of PPRV/Nigeria75/1. The C protein consists of 177 amino acid residues and is 91% identical with that of PPRV/Nigeria75/1. The conserved mRNA editing site (5'TTAAAAGGGCACAG) was present at positions 742-756 in the P gene, which is conserved in all other morbilliviruses. The CTT trinucleotide sequence is present at the N/P and P/M intergenic region, which is totally conserved in morbilliviruses. This will be the third sequence for the P gene of PPRV since that of the vaccine strain and a wild-type Turkish isolate has been published already.

Comparative sequence analysis of the large polymerase protein (L) gene of peste-des-petits ruminants (PPR) vaccine virus of Indian origin

The complete nucleotide sequence of the large polymerase (L) protein of the peste-des-petits ruminants (PPR) vaccine virus (PPRV Sungri/96) belonging to the Asian lineage was determined. The gene was 6643 nucleotides in length from the gene-start to the gene-end and encoded a polypeptide of 2183 amino acids. The PPRV Sungri/96 has a nucleotide homology of 94.1% for PPRV Nigeria 75/1 to 64.4% for Canine distemper virus. At amino acid level PPRV Sungri/96 has an amino acid identity of 96.2% with PPRV Nigeria 75/1 and 70.4% to 74.8% with other morbilliviruses. All the established domains in L protein characteristic of paramyxoviruses were also found to be present in PPRV Sungri/96. Phylogenetic analysis of different L proteins of morbilliviruses revealed five well-defined clusters as observed previously. The 3' trailer sequence of PPRV Sungri/96 is of 37 nucleotides long which is very similar to that of other morbilliviruses. To the best of our knowledge this is the first report describing the polymerase gene sequence of PPRV Indian isolate.

Development of a N gene-based PCR-ELISA for detection of Peste-des-petits-ruminants virus in clinical samples

A highly sensitive N gene-based PCR-ELISA for the detection of Peste-des-petits-ruminants virus (PPRV) was developed. The RT-PCR yielded a digoxigenin (DIG)-labeled product of 336 bp comprising a sequence from PPRV N gene, which was then detected by ELISA. The assay could detect the viral RNA in PPRV-infected tissue culture fluids with a titer as low as 0.1 TCID(50)/ml. The assay is 10,000 times more sensitive than a classical RT-PCR combined with agarose gel electrophoresis. The assay could detect the virus in the clinical samples, which were negative by conventional sandwich ELISA (S-ELISA). The percentage positivity of the assay in detecting the virus in clinical samples was 66.2% compared to 48.6% for S-ELISA. The assay was more sensitive than S-ELISA also in detecting the virus in early as well as late phases of the disease. In addition, the assay could also be used for differential diagnosis of PPRV and Rinderpest virus (RPV).

Sequence analysis of recent Indian isolates of foot-and-mouth disease virus serotypes O, A and Asia 1 from clinical materials

Partial nucleotide sequences of 1D gene of 38 isolates of foot-and-mouth disease virus (FMDV) of serotypes O, A and Asia 1 originating from various parts of India were determined. Field materials were subjected straight to RNA extraction, reverse transcription - PCR (RT-PCR) and sequencing. Also 3 FMDV vaccine strains, IND R2/75 (serotype O), IND 63/72 (serotype Asia 1) and IND 17/77 (serotype A) were included in the analysis. The seqences were compared mutually as well as with available corresponding sequences of other FMDV isolates, and their phylogenetic relationships were calculated. The deduced amino acid sequences showed that the serotype O isolates were relatively conserved as compared to serotype Asia 1 or A isolates from India. In phylogenetic analysis, the serotype O viruses clustered in two genotypes, one including the European vaccine strain (O1/K) and the other represented by the isolates from Bangladesh, India, Nepal and Turkey. The serotype Asia 1 viruses clustered in two groups of single genotype where the prototype strain from Pakistan (PAK 1/54) formed one group and the other was formed by the isolates from Bangladesh, Bhutan, India, Israel and Nepal. In serotype A viruses three well-differentiated genotypes were observed. The isolates from Azerbaijan, Bangladesh, Malaysia and India formed the first genotype. The second genotype was formed by isolates from Iran, Saudi Arabia and Turkey, while two recent Iranian isolates represented the third genotype. In India, the prevalence of at least one genotype could be identified in each serotype. This evolutionary clustering of isolates from the neighbor countries is not surprising, since these countries share border with India. The genetic relatedness between sequences of isolates from India and those from distant places is indicative of spread of the virus between the countries. Of importance is the fact that clinical materials proved useful for rapid generation of sequences and subsequent studying of molecular epidemiology of the disease.