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Articles by R. Tiwari
Total Records ( 10 ) for R. Tiwari
  K. Dhama , R.V.S. Pawaiya , S. Chakraborty , R. Tiwari and A.K. Verma
  Powassan encephalitis is a rare but severe disease caused by infection with Powassan virus (POWV). It is a tick-borne Flavivirus (family Flaviviridae) having single stranded Ribonucleic Acid (RNA) which is positive sense in nature. The virus has highest case-fatality rates and is associated with a very high incidence of severe neurologic sequelae. Humans contract POWV infection accidentally when they are exposed to areas where the virus, arthropod vector (an Ixodid tick) and the vertebrate natural hosts coexist. Reported incubation periods for Powassan virus range from 8 to 34 days. The disease is associated with a reactive inflammatory cellular infiltrate (chronic) of lymphocytes and macrophages that include the abundance of perivascular inflammatory cells and multiple foci of parenchymal cells in grey matter. Basically two diagnostic approaches are considered. First one is the direct detection of the virus or viral RNA in the initial (viremic) phase of infection by virus isolation in mammalian cell culture or by reverse transcriptase polymerase chain reaction (RT-PCR). Second is the indirect detection of specific immunoglobulins (IgM and IgG antibodies) with serological methods such as Enzyme Linked Immunosorbent Assay (ELISA); Immunofluorescence Assay (IFA) or Neutralization Tests (NTs). Phylogenetic analysis is important for genogrouping of the virus. Oligomers targeting specific locations in the RNA genome of the flavivirus have been used at present for successful suppression of viral gene expression. Strict hygienic and biosafety measures including tick control is pre-requisite for prevention of disease. The present review will give an insight to the details of disease caused by this arbovirus that may often prove fatal, its epidemiology, diagnosis, prevention and control measures to be adopted.
  K. Dhama , S. Chakraborty , R.V.S. Pawaiya , R. Tiwari and S. Kapoor
  Foamy viruses (FVs) are complex retroviruses under the genus Spumavirus of family Retroviridae. They cause induction of multinucleated giant cell formation which presents numerous vacuoles, giving the monolayer culture a foamy appearance. FVs can infect animals as well as humans. In case of the Human foamy virus (HFV), a defective variant (named ΔHFV or HFVΔTas) negatively interferes with replication of parental counterpart. Some species, such as rhesus macaques, African green monkeys, chimpanzees and cats harbor closely related yet serologically distinct FV subtypes. Unanticipated FV pathogenicity may warrant appropriate attention to biosafety practices to prevent occupational infections and the importance of additional studies to better define clinical outcome of these zoonotic infections. During cross-species infection and subsequent passages a rapid and fatal disease can occur, with changes from nonpathogenic to pathogenic potentials. In persons occupationally exposed to non-human primates, Simian foamy virus (SFV) infection occurs persistently showing that simian retroviruses cross into humans more frequently. Simian Immunodeficiency Viruses (SIV), mostly are nonpathogenic in their natural hosts but during cross-species infection a rapid and fatal disease can occur. Enzyme Immuno Assay (EIA), Western blot analysis and Polymerase Chain Reaction (PCR) amplification are the important diagnostic tests for FVs. FVs are also being exploited as potential vectors that can be used for gene therapy which is gaining much attention of the researchers worldwide. Strengthening sero-epidemiological as well as molecular investigations and public health surveillance programme along with extra precautions while transferring xenograft are some of the approaches to prevent these viral infections.
  K. Dhama , R.V.S. Pawaiya , K. Karthik , S. Chakraborty , R. Tiwari and A.K. Verma
  Equine Encephalosis (EE) is an arthropod borne febrile non contagious disease of equines. The causative virus, Equine encephalosis virus (EEV), has several serotypes (EEV1-EEV7) and the virus has been reported from southern Africa including Kenya, Botswana and South Africa. EEV was first isolated in 1967 from horses in the Republic of South Africa. Like the African horse sickness virus (AHSV) EEV is also endemic in southern Africa. In most of the country, EE virus in comparison to AHSV has a higher transmission rate. Two species in the Culicoides imicola species complex, C. imicola (senso stricto) and C. bolitinos are known to transmit EEV. Zebra and elephants can act as maintenance host of the virus, making the elimination of the virus difficult. Outbreaks of EEV infection is reported to be associated with equine foetus abortion during the first 5-6 months of gestation. 32P-labelled genomic probes of EEV are used for detection of viral Ribonucleic Acid (RNA). Sero-epidemiological tools for the detection of antibodies against EEV include Serum Neutralization Test (SNT) and Enzyme Linked Immunosorbent Assay (ELISA). A novel real time Polymerase Chain Reaction (PCR) assay has also been developed for the detection of EEV by targeting the gene Viral Protein (VP)-7. There is no specific treatment or vaccine available for this virus. Supportive treatment can only be provided. Management of horses in the stable is the key to control the spread of EEV in equines along with follow up of good biosecurity measures. The present review deals with all these aspects of the infection caused by this virus to enrich knowledge of researchers and equine/stud farm owners and the industry.
  K. Dhama , R.V.S. Pawaiya , S. Chakraborty , R. Tiwari and A.K. Verma
  Toroviruses are responsible for causing gastroenteritis in animals and humans. These are enveloped viruses with non-segmented and positive-sense (single stranded) RNA genome of 20 to 25 kilobases, pleomorphic and are associated with diarrhea in cattle, sheep, goat, pig and other animals and also in human beings. Morphological appearance of viruses is spherical/oval, elongated or kidney shaped. These show Torovirus-like (tubular and torus nucleocapsid in the cytoplasm of infected cells) appearance under the electron microscope and are approximately 100-140 nm in diameter, surrounded by club-shaped projections of 15-20 nm in length. Clinical signs of the disease are pyrexia, diarrhoea, dehydration, lethargy and depression in calves as well adults. In calves, the virus may lead to anorexia, mucoid faeces and neurological signs like generalised weakness, paralysis, inability to stand along with trembling and sudden death. In faecal samples, these can be identified by electron microscopy. Immunological tests Include Immuno-electron Microscopy (IEM), Haemagglutination Inhibition (HI), Enzyme Linked Immunosorbent Assay (ELISA) and southern blot. The molecular assays are reverse transcription-polymerase chain reaction (RT-PCR), nested-RT-PCR and SYBR Green real-time RT-PCR. Combined use of ELISA and RT-PCR are considered is a practical approach for epidemiological studies of bovine torovirus. At present, no vaccine is available for torovirus. The only control measures available are good hygiene and sanitary conditions along with isolation of infected animals. The present review highlights the salient features of the torovirus, their epidemiology, clinical signs, diagnosis, treatment and suitable prevention and control measures to be adopted.
  K. Dhama , R.V.S. Pawaiya , S. Chakraborty , R. Tiwari , M. Saminathan and A.K. Verma
  Coronaviruses are positive-sense single-stranded ribonucleic acid (RNA) viruses causing a broad spectrum of diseases in domestic and wild animals including poultry and rodents. Based on antigenic and genetic similarities coronaviruses have been subdivided into 3 major antigenic groups. They infect and produce disease in multiple species of animals, human beings (group 1 and 2) and birds (group 3). Equine coronavirus (ECV) causes enteritis in foals. Complete genome of first ECV isolate NC99 strain has been recently sequenced. Cytolytic nature of the virus is responsible for occurrence of lesions in the small intestine, thereby causing diarrhea. Demonstration of Coronavirus antigens in clinical samples is test of choice for diagnosis. By electron microscopy (negative staining) Coronavirus like particles can be identified in fecal samples. Coronavirus antigen in fecal samples can be detected by antigen capture enzyme linked immuno-sorbent assay (ELISA). Molecular detection tool like reverse-transcriptase polymerase chain reaction (RT-PCR) has made the diagnosis more accurate. Virus characterization along with genogrouping has become easier these days with the advent of proteomics and phylogenetic studies. Currently, no vaccine is available for ECV. Biosecurity measures if adopted strictly prevent the disease. The present review highlights the salient features of the Coronavirus in general with special reference to ECV and the disease it causes in equines, its epidemiology, diagnosis and appropriate prevention and control measures to be adopted. The review would be helpful for understanding the virus/disease in a better way and alleviating economic losses to the equine/stud farm owners.
  K. Dhama , R.P. Singh , K. Karthik , S. Chakraborty , R. Tiwari , M.Y. Wani and J. Mohan
  Spallanzani’s thought of Artificial Insemination (AI) has revolutionized the animal husbandry field, both in developing and developed countries, by improving the genetic potential of livestock and poultry; minimizing the managemental costs and holding the service of genetically superior males even after their death. AI in domesticated birds especially in turkey shows promising results unlike other domestic and wild animals. The advantages of AI are many which support the wide adaptation of this technique in the poultry industry to augment its growth. Making AI as an integral part of captive breeding programme for non-domesticated birds would facilitate the process of saving various endangered species of wild birds. However, there are various problems involved in case of birds which need to be addressed before implementing AI. Apart from these, AI also poses a risk of possible transmission of various infectious pathogens/diseases of poultry through semen or its contamination or during the process of insemination. Hence, careful and regular screening and monitoring of poultry will help to check the spread of such diseases. Novel methods are adopted to prevent the colonization of contaminant microbes in stored semen thereby minimizing the pathogen transfer. The recent advances in biotechnology and molecular biology need to be explored fully for early and rapid diagnosis of poultry diseases. This would help in formulating appropriate disease prevention and control strategies and thus safeguard poultry health and production. This review describes the salient facts about AI practices in poultry and possible transmission of infectious pathogens during insemination along with suitable prevention and control strategies to be adapted.
  D.B. Barad , B.S. Chandel , A.I. Dadawala , H.C. Chauhan , H.S. Kher , S. Shroff , A.G. Bhagat , S.V. Singh , P.K. Singh , A.V. Singh , J.S. Sohal , S. Gupta , K.K. Chaubey , S. Chakraborty , R. Tiwari , R. Deb and K. Dhama
  Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of chronic enteric granulomatous inflammation in animals and is known as Johne’s Disease (JD) or Paratuberculosis. JD, being spectral in nature, presents variable bacteriological, immunological and pathological spectra leading to variable efficacy of diagnostic methods at different points of time during the course of infection. The present study aimed to estimate the incidence of MAP in two important breeds of goats (Mehsani and Surti) from South Gujarat region of India by applying conventional, molecular and serological methods. A total 219 goats were screened and categorized into Group-I (123 Mehsani goats), Group-II (76 Surti goats) and Group-III, (20 Non-descript goats). Percent positivity by faecal smear examination, delayed type hypersensitivity (DTH), agar gel immunodiffusion (AGID), IS900 polymerase chain reaction) (PCR) and indigenous enzyme linked immunosorbent assay (ELISA) kit was 9.2 (7/76), 21.9 (27/123), 10.9 (24/219), 12.5 (5/40) and 43.3% (95/219), respectively. Of the 123 goats of Group-I, 27 (21.9%) were positive in DTH test. Of the 5 faecal positive goats which also showed clinical signs, 2 (3.5%) goats died during study were negative by Johnin test. Similar to these findings, sensitivity of Johnin test in goats ranged between 18-30% with least specificity in both preclinical and advanced stage of disease. Of 34 cases of caprine paratuberculosis, 73.5% goats were positive for Johnin test. In the present study, out of the 5 infected goats, 3 (60%) were positive in Johnin test. Rectal pinch smear examination was carried out in 27 DTH positive goats and all smears were negative for the presence of acid fast bacilli. Screening tests (Indigenous ELISA and DTH) showed very high incidence of MAP infection in the goat population. The utility of multiple diagnostic tests is suggested for confirmatory detection and epidemiological diseases investigations of MAP in animals.
  A. Kumar , S.V. Singh , A.K. Srivastava , N.K. Gangwar , P.K. Singh , S. Gupta , K.K. Chaubey , R. Tiwari , S. Chakraborty and K. Dhama
  Johne’s Disease (JD), caused by Mycobacterium avium subspecies paratuberculosis, is endemic in domestic animals and adversely affects dairy industry worldwide. In the present study, efficacies of ‘Indigenous’and commercial (Gudair, Spain) vaccines were evaluated for control of JD in experimentally challenged goats. Goats were grouped into Sham-immunized, Indigenous and Gudair vaccine groups. Vaccinated kids were challenged at 50 and 270 Days Post Vaccination (DPV), with 3×109 and 5×109 ‘Indian Bison Type strain ‘S 5’, respectively and sacrificed at 150 and 450 DPV after 1st and 2nd challenge, respectively. Vaccines were evaluated for improvements in physical condition (diarrhea, weakness, body coat color), clinical symptoms (shedding of bacilli, mortality, morbidity), immune responses (cell-mediated and humoral), pathology (gross and microscopic lesions) and production status (body weights, growth rates). Vaccinated goats gained higher body weights vis a vis sham-immunized. Mortality was higher in sham-immunized. Cell Mediated Immunity (CMI) response increased at 30 DPV and showed down regulation from 90 DPV onwards in vaccinated goats. Significant increase in humoral immune response was observed in vaccinated goats at 180 DPV and maintained till 450 DPV. Microscopical examination at 180 DPV showed reduced shedding in vaccinated groups, At 200 DPV, group 1 goats showed thickening of small intestine with corrugations specifically at ileocaecal junction, catarrhal enteritis with infiltration of mononuclear cells and epitheloid cells. In vaccinated groups, there were focal thickening of intestines at 450 DPV with lesions of chronic catarrhal enteritis and presence of lymphocyte, plasma cells and macrophages cells with a few epitheloid cells. Monitoring of MAP DNA in the blood of experimental goats of all the groups was done by testing of blood samples by Polymerase Chain Reaction (PCR) and the vaccinated groups of goats revealed MAP bacilli free status upto 300 DPV. Both the vaccines provided protection after challenge I, but since indigenous vaccine also protected goats after challenge II, was therefore superior. In conclusion, the indigenous vaccine must be exploited for its full potential for effective prevention and control of this economically important disease having public health concerns.
  K. Dhama , S. Rajagunalan , S. Chakraborty , A.K. Verma , A. Kumar , R. Tiwari and S. Kapoor
  The term food borne diseases or food-borne illnesses or more commonly food poisoning are used to denote gastrointestinal complications that occur following recent consumption of a particular food or drink. Millions of people suffer worldwide every year and the situation is quiet grave in developing nations creating social and economic strain. The food borne pathogens include various bacteria viz., Salmonella, Campylobacter, Escherichia coli, Listeria monocytogenes, Yersinia enterocolitica, Staphylococcus, Arcobacter, Clostridium perfringens, Cl. botulinum and Bacillus cereus and helminths viz., Taenia. They also include protozoa viz., Trichinella, Sarcocystis, Toxoplasma gondii and Cryptosporidium parvum. The zoonotic potential and the ability to elaborate toxins by many of the microbes causing fatal intoxication are sufficient to understand the seriousness of the situation. The viral agents being host specific their transmission to humans through food of animal origin is not yet confirmed although these animal viruses are similar to that of viruses infecting human. Food-borne bacteria; protozoa and helminthes have complex distribution pattern in the environment and inside the host system. This along with complexity of the maintenance chain and life cycle (of parasites) has made it difficult for epidemiologist and diagnostician to undertake any immediate safety measures against them. Serological and molecular diagnostic tests viz. ELISA, Latex agglutination test, Lateral flow assays, Immunomagnetic separation assays, molecular assays viz. Polymerase Chain Reaction (PCR), multiplex PCR, immuno-PCR, Realtime PCR, Random Amplified Polymorphic DNA (RAPD)-PCR, DNA microarrays and probes are widely used. Along with these LAMP assays, Capillary Electrophoresis-Single Strand Confirmation polymorphism (CE-SSCP); Flow cytometry, FISH, Biosensors, Direct epifluorescent filter technique, nanotechnology based methods and sophisticated tools (ultrasonography, magnetic resonance imaging and chlonangio-pancreatography) have aided in the diagnosis greatly. Most of the food-borne illnesses are self-limiting but in many instances antibiotics are recommended. With the increased drug resistance however use of chicken immunoglobulin, bacteriophage therapy, probiotics and herbs are gaining much importance these days. Adoption of proper prevention and control measures (including cooking procedures; hygiene, strict adherence to HACCP principles, public awareness and disease surveillance and monitoring) are the need of hour. All these have been discussed vividly in this review to help epidemiologists, diagnosticians, clinicians and above all common people so as to enable them avoid negligence regarding such serious issue.
  K. Dhama , S. Kapoor , R.V.S. Pawaiya , S. Chakraborty , R. Tiwari and A.K. Verma
  A fascinating and important arbovirus is Ross River Virus (RRV) which is endemic and epizootic in nature in certain parts of the world. RRV is a member of the genus Alphavirus within the Semliki Forest complex of the family Togaviridae, which also includes the Getah virus. The virus is responsible for causing disease both in humans as well as horses. Mosquito species (Aedes camptorhynchus and Aedes vigilax; Culex annulirostris) are the most important vector for this virus. In places of low temperature as well as low rainfall or where there is lack of habitat of mosquito there is also limitation in the transmission of the virus. Such probability is higher especially in temperate regions bordering endemic regions having sub-tropical climate. There is involvement of articular as well as non-articular cells in the replication of RRV. Levels of pro-inflammatory factors viz., tumor necrosis factor-alpha (TNF-α); interferon-gamma (IFN-γ); and macrophage chemo-attractant protein-1 (MAC-1) during disease pathogenesis have been found to be reduced. Reverse transcription-polymerase chain reaction (RT-PCR) is the most advanced molecular diagnostic tool along with epitope-blocking enzyme-linked immunosorbent assay (ELISA) for detecting RRV infection. Treatment for RRV infection is only supportive. Vaccination is not a fruitful approach. Precise data collection will help the researchers to understand the RRV disease dynamics and thereby designing effective prevention and control strategy. Advances in diagnosis, vaccine development and emerging/novel therapeutic regimens need to be explored to their full potential to tackle RRV infection and the disease it causes.
 
 
 
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