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Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants that leads to high morbidity and mortality thereby results in devastating economic consequences to the livestock industry. PPR is currently endemic across most parts of Asia and Africa, the two regions with the highest concentration of poor people in the world. Sheep and goats in particularly contribute significantly towards the upliftment of livelihood of the poor and marginal farmers in these regions. In this context, PPR directly affecting the viability of sheep and goat husbandry has emerged as a major hurdle in the development of these regions. The control of PPR in these regions could significantly contribute to poverty alleviation, therefore, the Office International des Epizooties (OIE) and Food and Agricultural Organization (FAO) have targeted the control and eradication of PPR by 2030 a priority. In order to achieve this goal, a potent, safe and efficacious live-attenuated PPR vaccine with long-lasting immunity is available for immunoprophylaxis. However, the live-attenuated PPR vaccine is thermolabile and needs maintenance of an effective cold chain to deliver into the field. In addition, the infected animals cannot be differentiated from vaccinated animals. To overcome these limitations, some recombinant vaccines have been developed. This review comprehensively describes about the latest developments in PPR vaccines., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Successful purification of multiple viruses from mixed infections remains a challenge. In this study, we investigated peste des petits ruminants virus (PPRV) and foot-and-mouth disease virus (FMDV) mixed infection in goats. Rather than in a single cell type, cytopathic effect (CPE) of the virus was observed in cocultured Vero/BHK-21 cells at 6th blind passage (BP). PPRV, but not FMDV could be purified from the virus mixture by plaque assay. Viral RNA (mixture) transfection in BHK-21 cells produced FMDV but not PPRV virions, a strategy which we have successfully employed for the first time to eliminate the negative-stranded RNA virus from the virus mixture. FMDV phenotypes, such as replication competent but noncytolytic, cytolytic but defective in plaque formation and, cytolytic but defective in both plaque formation and standard FMDV genome were observed respectively, at passage level BP8, BP15 and BP19 and hence complicated virus isolation in the cell culture system. Mixed infection was not found to induce any significant antigenic and genetic diversity in both PPRV and FMDV. Further, we for the first time demonstrated the viral interference between PPRV and FMDV. Prior transfection of PPRV RNA, but not Newcastle disease virus (NDV) and rotavirus RNA resulted in reduced FMDV replication in BHK-21 cells suggesting that the PPRV RNA-induced interference was specifically directed against FMDV. On long-term coinfection of some acute pathogenic viruses (all possible combinations of PPRV, FMDV, NDV and buffalopox virus) in Vero cells, in most cases, one of the coinfecting viruses was excluded at passage level 5 suggesting that the long-term coinfection may modify viral persistence. To the best of our knowledge, this is the first documented evidence describing a natural mixed infection of FMDV and PPRV. The study not only provides simple and reliable methodologies for isolation and purification of two epidemiologically and economically important groups of viruses, but could also help in establishing better guidelines for trading animals that could transmit further infections and epidemics in disease free nations.

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis (CL), a chronic debilitating disease of goats. In the present study, a total of 575 goats of Sirohi breed on an organized farm situated in the semi-arid tropical region of Rajasthan, India were clinically examined. Pus samples from superficial lymph nodes of 27 (4.7%) adult goats presenting clinical lesions suggestive of CL were collected for bacteriological and molecular analyses. Of these goats, 51.9% yielded C. pseudotuberculosis on the basis of morphological, cultural and biochemical characteristics. A polymerase chain reaction (PCR) assay targeting proline iminopeptidase gene specific to C. pseudotuberculosis was developed that confirmed all 14 bacterial isolates. The specificity of the PCR product was confirmed by sequencing of the 551-bp amplicon in both senses, showing 98-100% homology with published sequences. Thus, overall prevalence rate based on clinical, bacterial culture and PCR assay were found to be 4.7%, 2.4% and 2.4%, respectively. The PCR assay developed in this study was found to be specific and rapid, and could be used for confirmation of CL in goats as an alternative method to generally cumbersome, time-consuming and less reliable conventional methods.

The diagnosis of subclinical paratuberculosis is still considered a major problem worldwide. As part of investigating diagnostic strategies for the paratuberculosis infection, sequential results of various diagnostic methods in a progressive experimental infection in goats were evaluated. Twenty-three goat kids were divided into three groups: the infected, contact and control, comprising 10, five and eight goats respectively. Animals of the infected group were orally inoculated on seven occasions with 5 ml of inoculum containing 2 x 10(9)Mycobacterium avium ssp. paratuberculosis per ml. Lymphoycte proliferation test using johnin PPD detected paratuberculosis infection from 60 days post-infection (DPI) onwards. The johnin PPD was found to be a better antigen for the proliferative assays as compared with the sonicated antigen. The faecal smear examination with acid-fast staining detected more goats as positive than bacterial culture and polymerase chain reaction (PCR). Lipoarabinomannan enzyme-linked immunosorbent assay (ELISA) started detecting infected goats from 150 DPI onwards followed by indirect ELISA and agar gel immunodiffusion from 180 DPI onwards. Histological examination was confirmatory and detected five infected goats as positive.

Comparative efficacy of an IS900 tissue PCR, bacterial culture, johnin, agar-gel immunodiffusion (AGID) and absorbed-ELISA tests was investigated in 43 goats naturally infected with paratuberculosis. On histological examination, tissue sections from all animals showed typical granulomatous inflammatory changes. The lesions were classified as multibacillary (MB) (n=30), which had diffuse granulomatous lesions with abundant acid-fast bacilli (AFB), and paucibacillary (PB) (n=13), which had focal or multifocal granulomatous lesions with few AFB. The sensitivities of johnin test, tissue culture, faecal culture, tissue PCR, AGID and ELISA were 68% (17/25), 100% (30/30), 84.6% (22/26), 100% (30/30), 96.2% (25/26) and 100% (26/26) in MB goats, and 88.8 (8/9), 46.1% (8/13), 40% (4/10), 61.5% (8/13), 50% (5/10), and 70% (7/10) in PB goats, respectively. Except for the johnin test, which showed higher sensitivity in PB goats, all other tests displayed significantly higher sensitivities in MB goats. The results indicate the usefulness of tissue PCR, culture and serological tests in the diagnosis of clinically affected paratuberculous goats, especially with multibacillary pathology.

A dose of 10(10) Mycobacterium avium subspecies paratuberculosis was administered orally on seven occasions to produce experimental paratuberculosis infection in 10 5-8-week-old goat kids. Bacteriological, immunological, and histopathological changes, their relationships, and the efficacy of the commonly used diagnostic methods were studied during the progressive disease up to 270 days postinfection (DPI). Significant lymphocyte proliferative responses in the peripheral blood of five goats were detected as early as 60 DPI. A lymphoproliferative test was also performed on lymphocytes purified from different compartments of the guts of five infected and five control goats. Significant proliferative responses were observed in lymphocytes of jejunal compartments of all five goats, of which four had also significant lymphocyte proliferation in the blood. The ileal lymphocytes from two goats, one each at 120 and 270 DPI, had significant proliferation. The histological lesions were mainly observed in the gut-associated lymphoid tissues of the ileocecal valve, the ileum, and the terminal jejunum. Acid-fast bacilli were demonstrated in the lesions of two goats at 60 and 210 DPI. Bacterial culture showed poor sensitivity, detecting positive results for only one goat in the fecal and tissue samples at 210 DPI, whereas polymerase chain reaction (PCR) detected one goat in fecal sample at 210 DPI and two goats in tissue samples at 60 and 210 DPIs, respectively. Enzyme-linked immunosorbent assay and agar gel immunodiffusion test were found to be 100% sensitive from 180 and 210 DPI onwards, respectively.

Peste des petits ruminants (PPR) is an emerging, economically important viral disease of goats and sheep in the Indian subcontinent. In the present investigation, 15 hill goats were experimentally infected with 2 ml of 10% splenic suspension of a virulent isolate of PPR virus (PPR/Izatnagar/94) that had caused heavy mortality (>75%) in goats during 1994 outbreaks in northern India. More than 86% (13 of 15) animals died between 9 and 13 days post inoculation at the height of temperature or when temperatures were declining. Necropsy findings included congestion of gastrointestinal tract (GIT), nasal sinuses, consolidation of antero-ventral lobes of lungs, engorged spleen, and occasionally oedematous lymph nodes. Histopathological examination of major organs of GIT revealed degeneration and necrosis of labial mucosa, severe mucosal and submucosal congestion, degeneration and necrosis of intestinal epithelium and lymphoid cell depletion from Peyer's patches along with presence of syncytia at times. Lungs showed broncho-interstitial changes and presence of intracytoplasmic and intranuclear eosinophilic inclusions in alveolar macrophages and syncytial cells. These changes in lungs were frequently complicated with serofibrinous pneumonia (57%, eight of 14). Lymphocytolysis and occasional syncytia formation were evident in the lymphoid tissues. Immunohistochemical (IHC) findings included presence of PPR virus antigen in the labial, intestinal, and bronchiolar epithelial cells, pneumocytes, macrophages and syncytial cells in lungs, and lymphoid (intact and necrotic) and reticular cells in lymphoid organs. The findings of the study indicated the highly virulent nature of the PPR virus isolate (PPR/Izatnagar/94), causing 100% mortality and characteristic pathological changes in the target organs such as lungs, intestines and lymphoid tissues. The results of the IHC study suggested that indirect immunoperoxidase could be an alternative method in the absence of more sophisticated methods of laboratory diagnosis of PPR virus infection in goats.

An enzyme-linked immunosorbent assay (APA-ELISA) using an immunoaffinity-purified antigen was developed and compared with the unabsorbed and absorbed ELISA procedures, using a crude antigenic preparation, for its efficacy in detecting antibodies in goat sera against Mycobacterium ovium paratuberculosis. Serum samples from 89 goats belonging to three different flocks, two with a history and evidence of paratuberculosis and one without it, were subjected to each ELISA, which had been standardized on known positive sera from goats experimentally infected with paratuberculosis. Faecal culture, faecal examination and histopathology were used as indicators of infection. The diagnostic sensitivities of the unabsorbed, absorbed and APA-ELISA were 81.8%, 77.3% and 77.3% and the specificities were 90.6%, 93.7% and 96.8%, respectively. The positive predictive values of APA-ELISA (94.4%) was the highest, followed by absorbed ELISA (80.9%) and unabsorbed ELISA (72.0%). The negative predictive values for APA-ELISA, absorbed ELISA and unabsorbed ELISA were 93.0%, 92.7% and 93.8%, respectively. The results indicated the value of APA-ELISA in avoiding the need to absorb individual test sera with Mycobacterium phlei and giving more consistent results than the absorbed ELISA. The APA-ELISA was also better than the other two procedures in terms of specificity and positive predictive values.