P Roy

Tamil Nadu Veterinary and Animal Sciences University, Chennai, Tamil Nadu, India

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Publications (23)26.72 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The bursas of Fabricius of 48 broiler chickens (meat type) of age groups 3 to 7 wk, affected with infectious bursal disease (IBD) were tested by counterimmunoelectrophoresis (CIE) by using 3 different buffers, namely, barbital buffer, Tris-glacial acetic acid-EDTA (TAE) buffer. and Tris-boric acid-EDTA buffer. Eighty-five percent of the samples were positive when the TAE buffer was used, whereas the Tris-boric acid-EDTA and barbital buffers yielded 81% positive test results. The barbital buffer. which is commonly used in CIE for diagnosis of IBD, is not readily available and is considered carcinogenic. The TAE buffer was found to be safe and was a Superior buffer for diagnosing IBD in a CIE test.
    The Journal of Applied Poultry Research 03/2008; 17(1):116-120. DOI:10.3382/japr.2007-00050 · 0.59 Impact Factor
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    The Journal of Applied Poultry Research 09/2006; 15(3). DOI:10.1093/japr/15.3.442 · 0.59 Impact Factor
  • Acta virologica 02/2005; 49(4):281-2. · 1.04 Impact Factor
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    ABSTRACT: Three fowl adenovirus 4 (FAV4) isolates from chicken and one from quail, all from Tamil Nadu, India were analyzed. The L1 loop variable region of hexon gene of these isolates was amplified by PCR and sequenced. The nucleotide sequences (442 bp) and deduced amino acid sequences of the four isolates were compared with those of other isolates of FAV4. The nucleotide sequences of the four isolates had a 98% homology with other Indian isolates and a 96% homology with Belgian and Russian isolates. The amino acid sequences of the four Indian isolates had a more than 98% homology with other Indian isolates and a more than 92% homology with Belgian and Russian isolates. Hence, the variable of L1 loop region of hexon gene was found to be highly homologous in all the FAV4 isolates tested both at nucleotide and amino acid level.
    Acta virologica 02/2005; 49(1):65-8. · 1.04 Impact Factor
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    The Veterinary record 09/2004; 155(9):273-4. DOI:10.1136/vr.155.9.273 · 1.63 Impact Factor
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    ABSTRACT: Seventy-five unvaccinated chickens were divided into three equal groups. Chickens in group A received RDVF [Lentogenic strain of Newcastle disease virus (NDV)] vaccine oculonasally at 7 d of age and through drinking water at 4 wk of age. Chickens in group B were vaccinated with LaSota (Lentogenic strain of NDV) in the same way. Group C birds were kept as unvaccinated challenge controls. Five birds from each of these groups were moved to separate pens at 7 wk of age and were challenged with a field isolate No. 105 of virulent NDV (C 1 , based on monoclonal antibody grouping or Asiatic type, which was isolated from a disease outbreak). Similarly, five birds from each of the groups were moved to different pens at same age and challenged with the reference strain of the virulent NDV. All the unvaccinated birds died postchallenge, but both vaccinated groups withstood the challenge. Serum samples were collected from all three groups at different times, and antibody levels (against NDV) were measured by hemagglutination inhibition test, passive hemagglutination test, and enzyme-linked immunosorbent assay. The possibility of Asiatic-type NDV causing outbreaks in commercially vaccinated flocks is discussed in this paper.
    The Journal of Applied Poultry Research 06/2003; 12(2). DOI:10.1093/japr/12.2.169 · 0.59 Impact Factor
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    ABSTRACT: The pathogenicity of one isolate of Salmonella typhimurium, four isolates of Salmonella heidelberg, three isolates of Salmonella kentucky, two isolates of Salmonella montevideo, one isolate of Salmonella hadar, and two isolates of Salmonella enteritidis (SE), one belonging to phage type (PT)13a and the other to PT34, was investigated in specific-pathogen-free chicks. Three hundred eighty-four chicks were separated into 16 equal groups of 24 chicks. Thirteen groups were inoculated individually with 0.5 ml of broth culture containing 1 x 10(7) colony-forming units (CFU) of either S. typhimurium (one source), S. heidelberg (four sources), S. montevideo (two sources), S. hadar (one source), S. kentucky (three sources), SE PT 13a (one source) or SE PT 34 (one source) by crop gavage. Two groups of 24 chicks were inoculated in the same way with 1 x 10(7) CFU of SE PT4 (chicken-CA) and Salmonella pullorum. Another group of 24 chicks was kept as an uninoculated control group. The chicks were observed daily for clinical signs and mortality. Isolation of salmonella was done from different organs at 7 and 28 days postinoculation (DPI). All the chicks were weighed individually at 7, 14, 21, and 28 DPI. Two chicks chosen at random from each group were euthanatized and necropsied at 7 and 14 DPI and all the remaining live chickens, at 28 DPI. Selected tissues were taken for histopathology at 7 and 14 DPI. Dead chicks were examined for gross lesions and tissues were collected for histopathology. Chicks inoculated with S. pullorum had the highest mortality (66.66%), followed by S. typhimurium (33.33%). Chicks inoculated with S. heidelberg (00-1105-2) and SE PT4 (chicken-CA) had 12.5% mortality and 8.3% mortality, respectively, with SE PT 13a. Ceca were 100% positive for salmonellae at acute or chronic infection compared with other organs. Mean body weight reduction ranged from 0.67% (inoculated with S. kentucky 00-926-2) to 33.23% (inoculated with S. typhimurium 00-372) in the inoculated groups at different weeks compared with uninoculated controls. Gross and microscopic lesions included peritonitis, perihepatitis, yolk sac infection, typhilitis, pneumonia, and enteritis in some groups, especially those inoculated with S. typhimurium, S. heidelberg (00-1 105-2), SE PT4 (chicken-CA), and S. pullorum.
    Avian Diseases 10/2001; 45(4):922-37. DOI:10.2307/1592871 · 1.11 Impact Factor
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    ABSTRACT: Newcastle disease virus isolated from an outbreak in racing pigeons in India was found to be velogenic, based on the mean time to death in 10-day-old embryonated hen's eggs, the intravenous pathogenicity index in 6-week-old chickens and the pathogenesis in chickens and pigeons. The virus induced disease in chickens without prior adaptation in chickens. The virus was antigenically unusual since it could not be grouped with the available panel of monoclonal antibodies at the World Reference Laboratory for Newcastle disease, UK. However, commercially available lentogenic and mesogenic vaccines provided 100% protection to chickens against this antigenically unusual NDV.
    Tropical Animal Health and Production 07/2000; 32(3):183-8. DOI:10.1023/A:1005291800355 · 0.97 Impact Factor
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    ABSTRACT: During 1993, outbreaks of Newcastle disease occurred on many farms in Tamilnadu, India. Six Newcastle disease virus (NDV) isolates were obtained from the chickens on five different farms and from the birds on one duck farm during outbreaks of the disease. All the isolates were characterized as velogenic, based on the mean death time, intravenous pathogenicity index, intracerebral pathogenicity index (ICPI), stability of haemagglutinin at 56 degrees C, agglutination of equine erythrocytes, haemagglutination elution pattern and adsorption of haemagglutinin by chick brain cells. The isolate obtained from ducks resembled a group D strain, based on its ICPI and its reaction with a panel of monoclonal antibodies. The other five NDV isolates obtained from chickens were placed in groups B(1), C1(2) and D(2) on the basis of their binding patterns with the panel of monoclonal antibodies. In challenge experiments, it was found that LaSota vaccine provided 100% protection against each of these field isolates and against a local NDV strain obtained from the Institute of Veterinary Preventive Medicine, Tamilnadu, India, while unvaccinated chickens succumbed to challenge. The possible origin of epizootic viruses causing outbreaks in vaccinated flocks is discussed.
    Veterinary Research Communications 04/2000; 24(2):135-42. DOI:10.1023/A:1006416724050 · 1.36 Impact Factor
  • Tropical Animal Health and Production 03/2000; 32(1):19-22. DOI:10.1023/A:1005236901834 · 0.97 Impact Factor
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    ABSTRACT: Two inactivated vaccines were prepared against hydropericardium syndrome. The vaccine prepared from liver homogenate extracted with chloroform, inactivated with formalin and adjuvanted with liquid paraffin was highly effective against challenge in chickens aged three, five and seven weeks. Seroconversion following vaccination and challenge was assessed by the agar gel immunodiffusion test. The inactivated oil emulsion vaccine was highly effective against the syndrome in both experimental trials and field trials.
    The Veterinary record 11/1999; 145(16):458-9. DOI:10.1136/vr.145.16.458 · 1.63 Impact Factor
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    ABSTRACT: 120 white leghorn chickens primed with a lentogenic Newcastle disease (ND) live vaccine at 7 days of age were divided into three equal groups of 8 weeks of age and vaccinated with a live mesogenic ND vaccine (NDV). One group received only Newcastle disease mesogenic vaccine (RDVK) in normal saline, the second group received RDVK with groundnut oil as adjuvant and the third group received RDVK with liquid paraffin as adjuvant. Sera were collected at different time points for the assessment of antibody level against ND virus (NDV) by the haemagglutination inhibition (HI) test. The commonly used non-adjuvanted RDVK could not evince 100% protective HI titre beyond 11 weeks of age but in both the adjuvanted groups 100% protective HI titre was evident up to 20 weeks of age. On challenge at 20 weeks of age both the adjuvanted groups withstood challenge but in the non-adjuvanted group 80% of chickens withstood the challenge. A significant difference in immune response between the adjuvanted and non-adjuvanted groups was seen but not between both the adjuvanted groups. The advantage of vegetable oil (groundnut oil) as an adjuvant for live mesogenic ND vaccine has been discussed.
    Vaccine 07/1999; 17(20-21):2674-6. · 3.49 Impact Factor
  • The Veterinary record 04/1999; 144(11):299-300. · 1.63 Impact Factor
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    ABSTRACT: Newcastle disease virus (NDV) was isolated from the faeces of seven different species of clinically healthy captive wild birds. All seven NDV isolates were characterized as velogenic based on the mean death time in embryonated hens' eggs and the intracerebral pathogenicity index in day-old chicks. Three of the isolates were placed in group C1 based on the reactions with monoclonal antibodies. The role of captive wild birds in the epidemiology of Newcastle disease is briefly discussed.
    Tropical Animal Health and Production 11/1998; 30(5):299-303. DOI:10.1023/A:1005051106271 · 0.97 Impact Factor
  • Tropical Animal Health and Production 07/1998; 30(3):177-8. DOI:10.1023/A:1005011703895 · 0.97 Impact Factor
  • Tropical Animal Health and Production 03/1998; 30(1):37-9. DOI:10.1023/A:1005061326335 · 0.97 Impact Factor
  • Tropical Animal Health and Production 03/1998; 30(1):41-4. DOI:10.1023/A:1005013510406 · 0.97 Impact Factor
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    ABSTRACT: Seroconversion of 3 lentogenic commercial Newcastle disease (ND) vaccines and experimental V4 vaccines was compared based on the haemagglutination inhibition (HI) test against ND. It was found that for primary vaccination all the vaccines produced similar response but for vaccinations V4 and LaSota were better than RDVF. Eight-five samples each of serum, tears and feather pulp were collected from respective birds and antibody assessment was done against ND by HI test. The geometric mean HI titres (GMT) of serum samples were highest followed by tears and feather pulp samples before vaccination and 3 weeks after vaccination by oculonasal route and the difference was statistically significant (p < 0.01). Three weeks after booster vaccination by oculonasal route, however, the GMT of serum samples were highest followed by feather pulp and tear samples. The ease of collection of feather pulp samples and their role in ND serology is discussed.
    Tropical Animal Health and Production 02/1998; 30(1):31-5. DOI:10.1023/A:1005009309497 · 0.97 Impact Factor
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    ABSTRACT: Chickens were experimentally infected with Newcastle disease virus (NDV) and different organs were collected at point of death. Demonstration of NDV specific antigen in tissue samples were detected by haemagglutination (HA), agar-gel-immunodiffusion (AGID) and counterimmunoelectrophoresis (CIE) tests. Out of 51 samples tested 44, 27 and 37 were positive by HA, AGID and CIE respectively. The usefulness of AGID and CIE in Newcastle disease diagnosis is discussed.
    Tropical Animal Health and Production 12/1997; 29(4):231-4. · 0.97 Impact Factor
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    ABSTRACT: Seven hundred and ten blood samples were collected at random from commercial layers in Tamil Nadu on Whatman filter paper No. 1 instead of the conventional method of serum collection. The birds were subjected to different Newcastle disease (ND) vaccination schedules and samples were collected to study the vaccinal response to ND at field level. Eluates were obtained from sample areas of filter paper using Brij-35 solution [detergent] and subjected to the micro haemagglutination inhibition (HI) test for ND antibodies. The HI titre ranged from less than 2(4) to 2(9). The possible causes of poor immune response to ND vaccinations are discussed.
    Tropical Animal Health and Production 03/1997; 29(1):20-4. DOI:10.1007/BF02632339 · 0.97 Impact Factor

Publication Stats

109 Citations
26.72 Total Impact Points

Institutions

  • 1992–2008
    • Tamil Nadu Veterinary and Animal Sciences University
      • • Vaccine Research Centre
      • • Department of Animal Biotechnology
      Chennai, Tamil Nadu, India
  • 2003–2006
    • Washington State University
      Pullman, Washington, United States
  • 2001
    • California State University, Fresno
      Fresno, California, United States
  • 1994–2000
    • Kerala Veterinary and Animal Sciences University
      Kalpatta, Kerala, India