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Biomedical subjects

R Mahalingam

Publications and source records attributed to R Mahalingam.

At least 55 records · Page 3Linked to original sources
PubMed1992

Molecular analysis of simian varicella virus DNA.

Clinical and pathological studies indicate that simian varicella virus (SVV) infection in primates is the counterpart of human varicella zoster virus (VZV) infection. The SVV and VZV genomes are also similar in size and structure. To extend studies of SVV DNA, we analyzed virus DNA from African green monkey kidney cells infected with the Delta-herpes-virus strain of SVV. The infectivity of SVV DNA was 88 PFU/micrograms. The buoyant density of SVV DNA, determined by isopycnic banding in CsCl gradients, was 1.700 +/- 0.002 g/ml, corresponding to a G + C molar ratio of 40.8%. The size of SVV DNA, estimated by analysis of restriction endonuclease digestion products and pulsed-field gel electrophoresis was 125.1 and 124.9 kbp, respectively. Electron microscopy of SVV DNA revealed a long region of 110.0 kbp, a unique short (Us) region of 5.1 kbp, and inverted repeat regions of 7.5 kbp flanking the Us. An EcoRI map of SVV DNA revealed two fragments not previously reported; our complete Pstl map also shows some differences. Mapping of SVV DNA with an additional restriction enzyme, measurement of full-length SVV DNA molecules, and the first use of pulsed-field electrophoresis to size SVV DNA, confirm and extend Gray's recent finding that SVV DNA has the same size and molecular configuration as VZV. We also show for the first time that the density of SVV DNA is similar to that of VZV DNA and that SVV DNA is infectious.

Animals↗
PubMed1992

Peripheral blood mononuclear cells of the elderly contain varicella-zoster virus DNA.

Peripheral blood mononuclear cells (PBMC) from humans of different ages were analyzed for DNA sequences specific for varicella-zoster virus (VZV) genes 29 and 62 by polymerase chain reaction (PCR). Neither VZV gene was detected in DNA from umbilical cord blood PBMC of 10 infants or from blood PBMC of two 3-year-old children. In 22 humans less than 60 years old, gene 29 was not detected, and gene 62 was detected in only one subject. In 33 humans greater than 60 years old, including patients with postherpetic neuralgia, PBMC from 4 subjects contained gene 29, 4 contained gene 62, and 1 contained both genes. The presence of VZV DNA correlated significantly with age (P less than .05, chi 2 and logistic regression analysis), but not with gender or postherpetic neuralgia.

Adult↗
PubMed1992

Restricted transcription of varicella-zoster virus in latently infected human trigeminal and thoracic ganglia.

Normal human trigeminal and thoracic ganglia latently infected with varicella-zoster virus (VZV) were identified by polymerase chain reaction (PCR). Total RNA was extracted from these ganglia and treated with DNase until ganglionic RNA was free of VZV DNA as determined by PCR. Radiolabeled cDNA synthesized by priming with random oligonucleotides was hybridized to Southern blots containing recombinant clones that spanned greater than 95% of the VZV genome. The single region of the VZV genome detected was the 12.5-kb SalI C fragment located in the unique long segment of the viral genome. Two additional regions of the VZV genome, EcoRI G and SalI B, were detected in RNA from adult dorsal root ganglia and infant nervous system tissue.

Adult↗
PubMed1992

Varicella-zoster virus reactivation without rash.

Reactivation of varicella-zoster virus (VZV) leads to localized zoster (shingles), a syndrome characterized by pain and a vesicular rash. Rarely, patients experience radicular pain without zosteriform rash, cases that have been regarded as zoster sine herpete (zoster without rash). Virologic evidence for zoster sine herpete is sparse. However, VZV can produce other neurologic and visceral diseases in the absence of rash or radicular pain. The clinical and virologic features of zoster sine herpete and other disorders produced by VZV without rash are reviewed. Evidence is also presented for the detection of VZV DNA in human blood mononuclear cells of elderly individuals in the absence of skin lesions or other VZV-associated neurologic or systemic disease.

Aged↗
PubMed1992

Specific lysis of targets expressing varicella-zoster virus gpI or gpIV by CD4+ human T-cell clones.

Varicella-zoster virus (VZV)-specific CD4-positive T cells are known to lyse targets expressing VZV antigen, but little is known of the glycoprotein specificity or phenotype of these cells. To test the ability of T cells to distinguish between gpI and gpIV (which share an antibody-defined epitope), we prepared clones from blood from four healthy individuals by limiting dilution. Among 68 T-cell clones from four donors which were VZV specific in tests of proliferation, 30 lysed autologous Epstein-Barr virus-transformed lymphoblasts which had been superinfected with a recombinant vaccinia virus which included the whole VZV gpI sequence. These clones were characterized as major histocompatibility complex class II restricted by inhibition of their cytotoxicity with HLA-DR and CD4 monoclonal antibodies. Twenty-one clones lysed targets expressing gpIV. Fifteen of these clones lysed targets expressing gpI and gpIV. Four clones with gpI-gpIV specificity were examined in detail, and their dual specificity was confirmed by cold target inhibition. These four clones failed to kill target cells infected with a mutant gpIV recombinant vaccinia virus from which amino acid residues 212 to 354 had been deleted. This region includes one of the two gpIV decapeptides which have 50% homology with amino acids 111 to 121 of gpI. Our data confirm that T-cell-receptor-associated structures are required for specific lysis of VZV targets and indicate that (i) gpI-specific CD4 cytotoxic T cells outnumber gpIV-specific T cells in blood and (ii) 50% of gpI-specific T-cell clones also lyse gpIV-expressing targets.

CD4-Positive T-Lymphocytes↗
PubMed1992

Acute simian varicella infection. Clinical, laboratory, pathologic, and virologic features.

Five African green monkeys inoculated intratracheally with 7.5 x 10(3) to 1.4 x 10(5) plaque-forming units of simian varicella virus (SVV) were subjected to clinical, laboratory, pathologic, and virologic analyses to study the pathogenesis of acute varicella. All animals developed viremia and rash and were sacrificed 8 to 11 days post-infection. No serum was available for postmortem serologic studies. Examination of multiple organs for pathologic changes and for SVV-specific antigen and nucleic acid revealed inflammation, hemorrhagic necrosis, and intranuclear Cowdry A inclusions in liver, lung, lymph node, and spleen; mild inflammation without necrosis in adrenal gland, kidney, and bone marrow, and SVV-specific antigen and nucleic acids in all viscera examined. No pathologic changes, SVV antigen or nucleic acids were detected in the spinal cord or in the brain from any of the monkeys. Ganglia revealed mild inflammation but no necrosis, and intranuclear inclusion bodies in non-neuronal cells of one trigeminal ganglion; SVV antigen and nucleic acids were detected in both non-neuronal and neuronal cells in ganglia. The pathologic and virologic findings in viscera are consistent with those described in viscera of humans with disseminated zoster, but the mild inflammatory changes in ganglia during acute simian varicella infection contrast with the extensive hemorrhagic necrosis and intranuclear inclusion bodies seen in human ganglia after disseminated varicella or zoster. Nevertheless, these studies show that ganglia become infected with varicella virus during primary infection, although the route of primary ganglionic infection remains to be determined, and indicate the possible usefulness of the SVV model to study varicella pathogenesis in humans.

Acute Disease↗
PubMed1991

Simian varicella virus DNA in dorsal root ganglia.

Clinical, pathological, immunological, and virological evidence suggests that simian varicella virus (SVV) infection of primates is the counterpart of varicella-zoster virus infection of humans. To determine whether these two viruses share similarities in their properties during latency, we analyzed ganglia and brain of an African green monkey experimentally infected with SVV for the presence of viral nucleic acid using the polymerase chain reaction technique. We detected SVV DNA in dorsal root ganglia but not in brain of this monkey, which demonstrated no apparent clinical signs of SVV infection. Our results suggest that SVV becomes latent in monkey ganglia and that latency can develop in the absence of clinical varicella (chickenpox). These studies provide an animal model system to study varicella virus latency.

Animals↗
PubMed1991

Fatal varicella-zoster virus meningoradiculitis without skin involvement.

A 77-year-old man with T-cell lymphoma developed an acute fatal meningoradiculitis of cranial nerve roots and cauda equina, pathologically and virologically confirmed to be caused by varicella-zoster virus. This is the first report of fatal varicella-zoster virus-induced neurological disease in the absence of skin lesions. Varicella-zoster virus should be included in the differential diagnosis of acute radiculoneuropathy in the immunocompromised patient, particularly because antiviral treatment for varicella-zoster virus exists.

Aged↗
PubMed1991

Preherpetic neuralgia.

We have encountered six zoster patients whose pain preceded rash by 7 to more than 100 days. Pain was severe, burning, and radicular, and located both in dermatomes different from, as well as in, the area of eventual rash. Two patients ultimately developed disseminated zoster with neurologic complications, one of zoster paresis, and the other, a fatal zoster encephalitis; both had been taking long-term, low-dose steroids. A third case of preherpetic neuralgia developed in a patient with prior metastatic carcinoma, and another case in a patient with an earlier episode of brachial neuritis. The final two cases of preherpetic neuralgia developed in individuals with no underlying disease. An extended period of pain before the onset of zoster rash has gone largely unrecognized.

Antigens, Viral↗
PubMed1990

Latent varicella-zoster viral DNA in human trigeminal and thoracic ganglia.

BACKGROUND: Some human herpesviruses become latent in dorsal-root ganglia. Primary infection with the varicella-zoster virus causes chickenpox, followed by latency, and subsequent reactivation leading to shingles (zoster), but the frequency and distribution of latent virus have not been established. METHODS: Using the polymerase chain reaction, we performed postmortem examinations of trigeminal and thoracic ganglia of 23 subjects 33 to 88 years old who had not recently had chickenpox or shingles to identify the presence of latent varicella-zoster viral DNA. Oligonucleotide primers representing the origin of replication of the varicella-zoster virus and varicella-zoster virus gene 29 were used for amplification. RESULTS: Among the 22 subjects seropositive for the antibody to the virus, both the viral origin-of-replication and gene-29 sequences were detected in 13 of 15 subjects (87 percent) in whom trigeminal ganglia were examined and in 9 of 17 (53 percent) in whom thoracic ganglia were examined. Viral DNA was not detected in brain or mononuclear cells from the seropositive subjects. None of three thoracic ganglia from the one seronegative subject contained varicella-zoster viral DNA. CONCLUSIONS: These findings indicate that after primary infection with varicella-zoster virus (varicella), the virus becomes latent in many ganglia--more often in the trigeminal ganglia than in any thoracic ganglion--and that more than one region of the viral genome is present during latency.

Adult↗
PubMed1990

Nucleotide sequence of the mitochondrial genome of Paramecium.

The nucleotide sequence for 40,469 bp of the linear Paramecium aurelia mitochondrial (mt) genome is presented with the locations of the known genes, presumed ORFs, and their transcripts. Many of the genes commonly encoded in mt DNA of other organisms have been identified in the Paramecium mt genome but several unusual genes have been found. Ribosomal protein genes rps14, rps12, and rpl2 are clustered in a region that also contains two other genes usually found in chloroplasts, but rpl14 is over 16 kbp away. The ATP synthase gene, atp9, is encoded in this mt genome, but the atp6, atp8, and COIII genes have not been identified. All of the identified genes are transcribed. Many mono- and poly- cistronic transcripts have been detected which cover most of the genome, including large regions where genes have yet to be identified. Based on sequence comparisons with known tRNAs, only those for phe, trp, and tyr are encoded in Paramecium mt DNA.

Animals↗
PubMed1990

In-vitro synthesis of functional varicella zoster and herpes simplex viral thymidine kinase.

The varicella zoster virus (VZV) and herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) genes were cloned into the transcription vector pGEM4. In-vitro translation (ivt) of RNA transcribed from these genes showed prominent expression of functional TK proteins with the expected molecular weights of 36 kD for VZV and 43, 39, and 38 kD for HSV-1. The TK proteins were recognized by rabbit anti-VZV and anti-HSV-1 antibodies, respectively. Analysis of the ivt products by thin-layer chromatography revealed the conversion of thymidine to its phosphorylated forms (TMP, TDP, and TTP) by both the VZV and HSV-1 TK genes. The estimated specific activities of the in-vitro translated VZV and HSV-1 TKs were comparable. VZV TK templates were linearized at internal restriction sites and RNAs transcribed from these templates directed the synthesis of polypeptides with sizes consistent with the colinearity of the VZV TK gene. Deletion of 107 amino acids at the carboxy terminus of the VZV TK gene abolished the in-vitro TK activity. In addition, immunoprecipitation of truncated proteins synthesized in vitro suggested the possible involvement of the region between amino acid residues 101 and 168 from the amino terminus of the VZV TK molecule in the formation of structures necessary for antigenicity.

Amino Acid Sequence↗
PubMed1990

Trans-activation of viral tk promoters by proteins encoded by varicella zoster virus open reading frames 61 and 62.

Plasmids containing the varicella zoster virus (VZV) open reading frames (ORFs) 61 and 62 were used in a transient co-transfection assay to test for trans-activation of the VZV and herpes simplex virus type 1 (HSV-1) thymidine kinase (tk) promoters. The trans-activating potential of the polypeptides encoded by these VZV ORFs, designated p51 and p140, was compared to that of their HSV-1 homologs ICP0 and ICP4, respectively. VZV p51 was functionally inactive in this system while p140 appeared to be a much stronger transcriptional activator than ICP4. Co-transfection of plasmids encoding VZV p140 and HSV-1 ICP0 resulted in a synergistic activation of the reporter gene as has been shown for the combination of ICP4 and ICP0.

Herpesvirus 3, Human↗
PubMed1990

Monoclonal antibody to immediate early protein encoded by varicella-zoster virus gene 62.

Monoclonal antibodies (mAbs) were prepared against varicella-zoster virus (VZV)-infected cell proteins, and 10 mAbs which reacted with nuclear antigens were selected. These mAbs recognized a major 175-180 kDa and three minor VZV-specific phosphoprotein species. Immunofluorescence staining of VZV-infected cells showed that the 175-180 kDa protein was synthesized within 6 h after infection. The synthesis of this protein was inhibited by cycloheximide (CH); however, reversal of CH treatment and addition of actinomycin D (ActD) resulted in the synthesis of the 175-180 kDa protein. To determine whether the 175-180 kDa protein seen in the infected cells is encoded by VZV immediate early (IE) gene 62, the predicted open reading frames of VZV genes 61 and 62 were cloned into pGEM transcription vectors. RNA was transcribed from each gene, translated in vitro and immunoprecipitated with a mAb which recognizes a major 175-180 kDa and three minor proteins. The reactivity of the in vitro translation products encoded by gene 62 with this mAb suggested that the 175-180 kDa protein is encoded by VZV IE gene 62.

Animals↗
PubMed1988

Regulation of varicella zoster virus gene 27 translation in vitro by upstream sequences.

Northern blot analysis revealed the presence of varicella-zoster virus (VZV) gene 27 transcripts in infected cells. The Sal I-G DNA fragment, located in the unique long segment of the VZV genome and containing overlapping genes 26 and 27, was analyzed in an in vitro transcription-translation system. Translation of RNA transcribed from these open reading frames showed prominent expression of gene 27. Four different subclones were constructed to contain gene 27 with and without 100 base pairs (bp) of upstream sequences. Translation of RNA from these constructs using wheat germ extract or rabbit reticulocyte lysate indicated that the sequences upstream from the predicted initiation codon (AUG) of gene 27 downregulated the expression of this gene at the level of translation and that the predicted AUG within gene 27 was preferentially used.

Animals↗
PubMed1988

Recognition of similar epitopes on varicella-zoster virus gpI and gpIV by monoclonal antibodies.

Two monoclonal antibodies, MAb43.2 and MAb79.0, prepared against varicella-zoster virus (VZV) proteins were selected to analyze VZV gpIV and gpI, respectively. MAb43.2 reacted only with cytoplasmic antigens, whereas MAb79.0 recognized both cytoplasmic and membrane antigens in VZV-infected cells. Immunoprecipitation of in vitro translation products with MAb43.2 revealed only proteins encoded by the gpIV gene, whereas MAb79.0 precipitated proteins encoded by the gpIV and gpI genes. Pulse-chase analysis followed by immunoprecipitation of VZV-infected cells indicated reactivity of MAb43.2 with three phosphorylated precursor species of gpIV and reactivity of MAb79.0 with the precursor and mature forms of gpI and gpIV. These results indicated that (i) MAb43.2 and MAb79.0 recognize different epitopes on VZV gpIV, (ii) glycosylation of gpIV ablates recognition by MAb43.2, and (iii) gpIV is phosphorylated. To map the binding site of MAb79.0 on gpI, the pGEM transcription vector, containing the coding region of the gpI gene, was linearized, and three truncated gpI DNA fragments were generated. RNA was transcribed from each truncated fragment by using SP6 RNA polymerase, translated in vitro in a rabbit reticulocyte lysate, and immunoprecipitated with MAb79.0 and human sera. The results revealed the existence of an antibody-binding site within 14 amino acid residues located between residues 109 to 123 on the predicted amino acid sequences of gpI. From the predicted amino acid sequences, 14 residues on gpI (residues 107 to 121) displayed a degree of similarity (36%) to two regions (residues 55 to 69 and 245 to 259) of gp IV. Such similarities may account for the binding of MAb79.0 to both VZV gpI and gpIV.

Amino Acid Sequence↗
PubMed1988

Detection of antibodies to varicella-zoster virus proteins in sera from the elderly.

Sera from 40 elderly individuals ranging in age from 60 to 94 years were tested for the presence of antibodies to varicella-zoster virus (VZV)-specific proteins. Sodium dodecylsulfate polyacrylamide gel electrophoresis analysis of lysates of VZV-infected BSC-1 cells labeled with either [35S]methionine or [3H]mannose and immunoprecipitated with human sera revealed the variable presence of VZV-specific antibodies to four VZV glycoproteins (gpI, gpII, gpIII, and gpIV), and three nonglycosylated proteins (155, 140, 32 kilodaltons, kDa). The predominant antibody response in the sera from the elderly was to VZV gpII and the 155-kDa species. In addition, some sera from elderly individuals without an identifiable history of varicella or zoster contained antibodies to VZV proteins, suggesting a possible subclinical infection in these patients. Finally a history of zoster in the elderly was significantly correlated (p = 0.02) with the presence of antibody to gpIV.

Aged↗