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Biomedical subjects

K Venugopal

Publications and source records attributed to K Venugopal.

71 records · Page 4Linked to original sources
PubMed1993

Nucleotide and deduced amino acid sequence of the envelope gene of the Vasilchenko strain of TBE virus; comparison with other flaviviruses.

A strain of tick-borne encephalitis virus known as Vasilchenko (Vs) exhibits relatively low virulence characteristics in monkeys, Syrian hamsters and humans. The gene encoding the envelope glycoprotein of this virus was cloned and sequenced. Alignment of the sequence with those of other known tick-borne flaviviruses and identification of the recognised amino acid genetic marker EHLPTA confirmed its identity as a member of the TBE complex. However, Vs virus was distinguishable from eastern and western tick-borne serotypes by the presence of the sequence AQQ at amino acid positions 232-234 and also by the presence of other specific amino acid substitutions which may be genetic markers for these viruses and could determine their pathogenetic characteristics. When compared with other tick-borne flaviviruses, Vs virus had 12 unique amino acid substitutions including an additional potential glycosylation site at position (315-317). The Vs virus strain shared closest nucleotide and amino acid homology (84.5% and 95.5% respectively) with western and far eastern strains of tick-borne encephalitis virus. Comparison with the far eastern serotype of tick-borne encephalitis virus, by cross-immunoelectrophoresis of Vs virions and PAGE analysis of the extracted virion proteins, revealed differences in surface charge and virus stability that may account for the different virulence characteristics of Vs virus. These results support and enlarge upon previous data obtained from molecular and serological analysis.

Amino Acid Sequence↗
PubMed1993

Sequencing and antigenic studies of a Norwegian virus isolated from encephalomyelitic sheep confirm the existence of louping ill virus outside Great Britain and Ireland.

We have carried out an antigenic analysis and nucleotide sequence comparison of the envelope glycoprotein of recognized louping ill virus strains isolated from Scotland with that of a Norwegian virus known to cause encephalomyelitis in sheep. Monoclonal antibodies with defined specificity for the louping ill virus envelope glycoprotein failed to distinguish between the Norwegian virus and prototype louping ill virus in indirect immunofluorescence, haemagglutination inhibition and neutralization tests. Nucleotide sequencing of the envelope glycoprotein and alignment of the deduced amino acid sequence with other known sequences revealed that the Norwegian virus closely resembles (> 95% identity for nucleotide and > 98% identity for amino acid sequences) louping ill virus. Maximum variation in identities among four strains of louping ill virus were 4.4% and 1.8% respectively for nucleotide and amino acid alignments. We conclude that sheep encephalomyelitis in Norway is caused by louping ill virus. These results imply that other viruses present in Europe and known to cause encephalitis/encephalomyelitis of sheep could be caused by louping ill virus.

Animals↗
PubMed1992

Heterologous resistance to superinfection by louping ill virus persistently infected cell cultures.

Louping ill virus, a tick-borne arbovirus readily established a persistent infection in porcine kidney (PS) cells after initially inducing minor cytopathic changes. Nucleotide sequence analysis of the envelope glycoprotein of the viral RNA recovered from the persistently infected cells showed no changes as compared with the virus used to establish persistent infections. More than 80 per cent of the cells contained virus specific antigen when analysed by indirect immunofluorescence microscopy. This persistently infected cell line resisted superinfection with either homologous or most heterologous flaviviruses. However, the yellow fever French neurotropic virus (YF FNV) multiplied in the persistently infected cells and evidence of dual infections in these cells was obtained using specific monoclonal antibodies in double labelling immunofluorescence tests. The relevance of these observations is discussed in the light of other evidence that tick-borne viruses can survive for long periods in wild animal species.

Animals↗
PubMed1992

Nucleotide sequence of the envelope glycoprotein of Negishi virus shows very close homology to louping ill virus.

Negishi virus, a member of the family Flaviviridae, was originally isolated in Japan, during an outbreak of Japanese encephalitis. Antigenically, however, Negishi virus resembles the tick-borne rather than the mosquito-borne flaviviruses. Monoclonal antibodies that bind louping ill virus showed a close antigenic relationship between louping ill and Negishi virus. The genes encoding the envelope glycoprotein of Negishi virus (strain 3248/49/P10) and louping ill virus (strain SB526) were cloned and sequenced. They showed a very close homology at both the nucleotide and deduced amino acid levels. Comparison with the known sequence of another strain of louping ill virus (strain 369/T2) and with other tick-borne flaviviruses showed that Negishi virus was more closely related to louping ill virus than to the other tick-borne viruses. The significance of this observation for virus evolution, virus distribution in the environment, and the potential use of nucleotide sequencing for rapid and precise identification of flaviviruses are discussed.

Amino Acid Sequence↗
PubMed1990

Lesions and immune responses produced in hamsters and guinea pigs inoculated with some strains of leptospira.

Pathogenic lesions and immune responses in hamsters and guinea pigs produced by three leptospiral serovars, viz. autumnalis, grippotyphosa, and pomona, and their pool were experimentally studied. Hepatic lesions precede renal localisation. The infections were documented by the demonstration of leptospires and histopathological study. The 2-Me sensitive IgM was responsible for MAT titres in the early immune response.

Animals↗
PubMed1979

Effect of pancuronium on intraocular pressure changes induced by succinylcholine.

The study was undertaken to evaluate the influence of pretreatment with a small dose of pancuronium on intraocular pressure changes associated with administration of succinylcholine and tracheal intubation. Thirty patients divided into control and study groups were anaesthetized with sodium thiopentone (3-5 mg mg.kg-1) and intubation with the aid of succinylcholine (1 mg.kg-1). The control group received saline pretreatment while the study group received pancuronium 1 mg three minutes before succinylcholine. Anaesthesia was maintained with nitrous oxide and oxygen (70:30). A Schiotz tonometer was used to measure intraocular pressure before induction of anaesthesia, one minute after succinylcholine and immediately after intubation. Patients in the control group demonstrated significant elevation of intraocular pressure at one minute after succinylcholine and immediately after intubation, while the study group showed no significant change at the same observation periods. These findings indicate that pretreatment with pancuronium 1 mg three minutes before succinylcholine may be beneficial in patients with high intraocular pressure and penetrating injuries of the eye.

Adolescent↗
PubMedDate not supplied

Molecular characteristics of very virulent European MDV isolates.

Marek's disease virus (MDV) strains with increasing virulence have been reported from many parts of the world. Many of these recent MDV isolates produce an acute early cytolytic disease with high mortality and severe atrophy of the lymphoid organs, thymus and the bursa of Fabricius. Although the degree of the atrophic changes and the virulence of the virus are correlated, the molecular basis of the increased virulence is not known. We examined the characteristics of the disease induced by 3 such MDV isolates, C12/130, MR36 and MR48, isolated from Europe. All the three viruses produce high early mortality and atrophy of the lymphoid organs. As a first step in understanding the determinants of the increased virulence of these isolates, we have compared the sequences of MEQ and the ICP4 genes of these three viruses with that of the published sequences. Some of the amino acid changes seen within the Meq and ICP4 proteins were conserved in all the three isolates and could account for the increased virulence characteristics.

Animals↗
PubMedDate not supplied

Autonomic dysfunction in extra-hepatic portal vein obstruction: correlation with cardiovascular haemodynamics.

Various autonomic dysfunctions (AD) are known to occur in cirrhosis of the liver. The haemodynamic abnormalities of cirrhosis have been correlated with AD and have prognostic implications. The relevance of AD in extrahepatic portal vein obstruction (EHPVO) is not well established. We evaluated AD and cardiac indices in 30 patients, 19 male and 11 female and compared the results with those of 10 controls. The mean age of the patients and controls was 23.77 +/- 1.33 and 20.5 +/- 2.51 years, respectively. Five standard autonomic function tests were done in all the patients. Cardiac output (CO) was measured by echocardiography. Anthropometric measurements were done to determine the cardiac index (CI = Cardiac output/Body surface area) and indicized peripheral vascular resistance (iPVR) was calculated using the formula: mean arterial pressure (MAP) x 80/CI. Each autonomic function test was given a score and the results were interpreted as normal, early or definite, according to the score. AD was recorded as normal in 5, early in 11 and definite in 14 patients. None of the controls had any abnormality in autonomic function. There was a significant difference in the baseline heart rate of controls and patients (76 +/- 2.55 v. 98.9 +/- 2.96 beats/min). There was no difference in the MAP (92.65 +/- 1.71 v. 81.7 +/- 1.99 mmHg), CI (2.99 +/- 0.15 v. 3.23 +/- 0.08), iPVR (2533.59 +/- 124 v. 2176 + 104). CI, iPVR and MAP were also calculated separately in patients in the normal (N), early (E) and definite (D) AD groups. Their respective values were as follows CI: N 3.44 +/- 0.19, E 3.44 +/- 0.19, D 3.23 +/- 0.6; iPVR: N 2150 +/- 75.4, E 2140 +/- 180, D 2372 +/- 142; MAP: N 86 +/- 3.01, E 85.8 +/- 3.59, D 90.79 +/- 3.09. Results are expressed as mean +/- SE. Unlike in cirrhotics, cardiovascular haemodynamics are not altered in patients with EHPVO, even in the presence of AD.

Adolescent↗
PubMedDate not supplied

Recombinant env-gp85 of HPRS-103 (subgroup J) avian leukosis virus: antigenic characteristics and usefulness as a diagnostic reagent.

We describe the construction of a recombinant baculovirus containing the cloned DNA encoding the gp85 envelope glycoprotein of HPRS-103 (subgroup J) avian leukosis virus fused to the carboxy-terminus of the affinity tag glutathione-S-transferase. The fusion protein was efficiently secreted into the supernatant medium of the infected insect cell culture and could be purified in a single step using immobilized glutathione. An enzyme-linked immunosorbent assay using the recombinant protein was found to be specific and sensitive for detection of HPRS-103 virus-specific antibodies in the sera of infected birds.

Animals↗