Biomedical subjects

R Mahalingam

Publications and source records attributed to R Mahalingam.

At least 37 records · Page 2Linked to original sources

PubMed1998

Localization of varicella-zoster virus gene 21 protein in virus-infected cells in culture.

Although four varicella-zoster virus (VZV) genes have been shown to be transcribed in latently infected human ganglia, their role in the development and maintenance of latency is unknown. To study these VZV transcripts, we decided first to localize their expression products in productively infected cells. We began with VZV gene 21, whose open reading frame (ORF) is 3,113 bp. We cloned the 5' and 3' ends and the predicted antigenic segments of the ORF as 1292-, 1280-, and 880-bp DNA fragments, respectively, into the prokaryotic expression vector pGEX-2T. The three VZV 21 ORFs were expressed as approximately 75-, 73-, and 59-kDa glutathione S-transferase fusion proteins in Escherichia coli. To prepare polyclonal antibodies that would recognize all potential epitopes on the VZV gene 21 protein, rabbits were inoculated with a mixture of the three fusion proteins, and antisera were obtained and affinity purified. Immunohistochemical and immunoelectron microscopic analyses using these antibodies revealed VZV ORF 21 protein in both the nucleus and cytoplasm of VZV-infected cells. When these antibodies were applied to purified VZV nucleocapsids, intense staining was seen in their central cores.

Animals↗

PubMed1998

Infectious simian varicella virus expressing the green fluorescent protein.

Clinical, pathologic, immunologic and virologic features of simian varicella virus (SVV) infection in primates closely resemble varicella-zoster virus (VZV) infection in humans. Such similarities provide a rationale to analyze SVV infection in primates as a model of varicella pathogenesis and latency. Thus, we constructed an SVV-expressing green fluorescent protein (SVV-GFP) by inserting the GFP gene into the unique short segment of the virus genome by homologous recombination. Analysis of recombinant viral DNA and the expressed proteins of plaque-purified SVV-GFP confirmed the location of the GFP insert and that the recombinant SVV expressed the 27 kDa GFP. Infection of monkey kidney cells in tissue culture with SVV-GFP revealed bright green fluorescence associated with the characteristic focal cytopathic effect produced by SVV infection. Microscopic examination of lung from a 3-month-old African green monkey 10 days after infection with SVV-GFP revealed bright green fluorescence in areas of acute necrotizing pneumonitis. SVV-GFP allows ready identification of cells infected with SVV both in vitro and in vivo, and will be useful for further analysis of varicella pathogenesis and latency in experimentally infected animals--studies not possible in humans.

Animals↗

PubMed1997

Identification of simian varicella virus homologues of varicella zoster virus genes.

Clinical, pathologic, immunologic and virologic features of simian varicella virus (SVV) infection in primates resemble human varicella-zoster virus (VZV) infection. Further, the SVV and VZV genomes are similar in size and structure, show striking homology in their configuration and DNA sequences, and encode antigenically related polypeptides. Although the entire VZV genome is present during latency in human ganglia, transcription is limited. VZV genes 21, 29, 62 and 63 are transcribed during latency, while genes 4, 10, 40, 51 and 61 are not transcribed. The entire VZV genome has been sequenced, but the SVV genome has not. Thus, to analyze SVV genes transcribed during latency, we have begun to identify SVV homologues of the above VZV genes. We used nick-translated [32p]-labeled-VZV open reading frame (ORF)-specific probes to screen Southern blots containing EcoRI-digested SVV genomic DNA and recombinant clones of SVV EcoRI and BamHI DNA fragments spanning approximately 97% of the virus genome. We showed that SVV homologues of VZV ORFs 4, 10, 29, 40, 51 and 61 mapped to SVV DNA fragments EcoRI I, A, N, BamHI E, EcoRI D and E, respectively. We also confirmed earlier reports that SVV homologues of VZV genes 21 and 63 mapped to SVV EcoRI DNA fragments H and C, respectively. Viral genes on the SVV and VZV genomes seem to be collinear.

Animals↗

PubMed1996

Expression of protein encoded by varicella-zoster virus open reading frame 63 in latently infected human ganglionic neurons.

The ganglionic cell type in which varicella-zoster virus (VZV) is latent in humans was analyzed by using antibodies raised against in vitro-expressed VZV open reading frame 63 protein. VZV open reading frame 63 protein was detected exclusively in the cytoplasm of neurons of latently infected human trigeminal and thoracic ganglia. This is, to our knowledge, the first identification of a herpesvirus protein expressed during latency in the human nervous system.

Adult↗

PubMed1996

Epstein-Barr virus--associated acute autonomic neuropathy.

A 44-year-old man developed blurry vision, photosensitivity, orthostasis, constipation, and acrodysesthesias after a febrile illness. The neurologic examination and ancillary studies were consistent with a dysautonomic small fiber neuropathy. The cerebrospinal fluid (CSF) contained both Epstein-Barr virus (EBV) DNA and antibody to EBV. This is the first report of an acute autonomic neuropathy with documented EBV infection in CSF.

Adult↗

PubMed1996

Zoster myelitis: improvement with antiviral therapy in two cases.

This report describes two patients with acquired immunodeficiency syndrome (AIDS) and herpes zoster myelopathy. Patient one had a T-8 myelitis that preceded the onset of T-8-distribution zoster and was followed by cervical myelopathy. Antibody to varicella zoster virus (VZV) was present in the CSF. He never received steroids or other immunosuppressive drugs, and his condition improved dramatically after treatment with intravenous acyclovir. The second patient had a rapidly progressive myelitis with paralysis of both legs. Detection of VZV DNA and antibody to VZV in his CSF led to successful treatment with famciclovir despite discontinuation of dexamethasone and earlier treatment failure with acyclovir. These cases support the idea that VZV myelopathy in the immunosuppressed host is caused by virus invasion. CSF analysis for antiviral antibody and for VZV DNA by polymerase chain reaction are helpful in establishing the diagnosis. Aggressive antiviral therapy is advised.

Acquired Immunodeficiency Syndrome↗

PubMed1996

Varicella zoster virus, a cause of waxing and waning vasculitis: the New England Journal of Medicine case 5-1995 revisited.

A 73-year-old man developed an ill-defined fatal vasculitis involving the central nervous system. The case report was published as a clinicopathologic exercise in February 1995 in The New England Journal of Medicine. We restudied the pathologic material and found both varicella zoster virus (VZV) DNA and VZV-specific antigen, but not herpes simplex virus (HSV) or cytomegalovirus (CMV) DNA or HSV- or CMV-specific antigen, in three of the five cerebral arteries examined. The inflammatory response, disruption of the internal elastic lamina, and detection of viral antigen were patchy from one artery to another, as well as within a given artery. A search for VZV should be conducted in cases of vasculitis when both the central and peripheral nervous systems are involved, when focal narrowing is present in large arteries, when brain imaging reveals infarction in gray and white matter, both deep and superficial, and when white matter is disproportionally involved. Zosteriform rash is not required for diagnosis.

Aged↗

PubMed1996

Another case of virologically confirmed zoster sine herpete, with electrophysiologic correlation.

A third virologically-confirmed case of thoracic-distribution zoster sine herpete is reported. Electromyography (EMG) of paraspinal muscles demonstrated frequent fibrillation potentials restricted to chronically painful thoracic root segments. Treatment with intravenous acyclovir and oral famciclovir were ineffective. These findings suggest the usefulness of EMG of muscles corresponding to painful dermatomes, combined with virologic studies, to support the diagnosis of zoster sine herpete.

Aged↗

PubMed1995

The vasculopathy of varicella-zoster virus encephalitis.

Varicella-zoster virus (VZV) encephalitis has become more prevalent in the era of acquired immunodeficiency syndrome and other immunosuppressive diseases and poses diagnostic and therapeutic challenges for clinicians, radiologists, and pathologists. Six cases studied at our institutions shed light on the patterns and pathogenesis of the disease. VZV encephalitis is predominantly a vasculopathy, involving small and large vessels, that generates seizures, mental changes, and focal deficits. Brain imaging reveals large and small ischemic or hemorrhagic infarcts, often both, of cortex and subcortical gray and white matter. Deep-seated white matter lesions often predominate and are ischemic and/or demyelinative, depending on the size of blood vessels involved and the amount of additional demyelination caused by infection of oligodendrocytes. The demyelinative lesions are smaller and less coalescent than those seen in progressive multifocal leukoencephalopathy.

Adult↗

PubMed1995

In situ polymerase chain reaction detection of varicella zoster virus in infected cells in culture.

Polymerase chain reaction (PCR) technology provides a means of identifying genes and studying their expression with specificity and precision. Combined with in situ hybridization (ISH), the amplified gene can be localized within cells. Cell gene sequences (human alpha-tubulin) were identified by PCR-ISH first in uninfected cells in culture, then in human blood mononuclear cells, and finally in sections of human liver. Varicella zoster virus (VZV) DNA was detected for the first time in virus-infected cells in culture by PCR-ISH, and compared to ISH alone. Efficient PCR-ISH was achieved by fixation of cells or tissue sections with 2% paraformaldehyde, by amplification under conditions of complete exposure of the samples to the reagents, and by detection of amplified products using non-radioactive digoxigenin-labeled oligonucleotide probes internal to the amplified DNA segment. PCR-ISH increased the detection of VZV DNA in infected cells 5-fold compared to ISH alone. Compared to ISH alone, PCR-ISH enhances significantly the detection of virus DNA in infected cells.

Animals↗

PubMed1995

Varicella-zoster virus (VZV) transcription during latency in human ganglia: prevalence of VZV gene 21 transcripts in latently infected human ganglia.

Reverse transcriptase-linked PCR was used to determine the prevalence of varicella-zoster virus (VZV) gene 21 transcription in latently infected human ganglia. Under conditions wherein reverse transcriptase-linked PCR detected > or = 1,000 transcripts, VZV gene 21 RNA, but not VZV gene 40 RNA, was found in ganglia but not other tissues from five of seven humans.

Base Sequence↗

PubMed1995

Persistence of varicella-zoster virus DNA in elderly patients with postherpetic neuralgia.

The most common complication of zoster in the elderly is postherpetic neuralgia, operationally defined as pain persisting longer than 1-2 months after rash. The cause of postherpetic neuralgia is unknown. Using polymerase chain reaction, we detected varicella zoster virus DNA in blood mononuclear cells from 11 of 51 postherpetic neuralgia patients, but not in any of 19 zoster patients without postherpetic neuralgia, or in any of 11 elderly individuals without a history of zoster. Blood mononuclear cells from nine of 27 serially-bled postherpetic neuralgia patients were positive for varicella zoster virus DNA; six were positive once, and three patients were positive more than once. Our results indicated that postherpetic neuralgia may be related to persistence of varicella zoster virus.

Aged↗

PubMed1994

Zoster sine herpete, a clinical variant.

Two otherwise healthy immunocompetent men, ages 62 and 66 years, experienced years of radicular pain without zoster rash. An extensive search for systemic disease and malignancy was negative. Varicella-zoster virus DNA, but not herpes simplex virus DNA, was found in the cerebrospinal fluid of the first patient 5 months after the onset of pain, and in the second patient 8 months after the onset of pain. Prolonged radicular pain without zoster rash combined with the presence of varicella-zoster virus in the cerebrospinal fluid indicates that both men had zoster sine herpete, and strongly supports this syndrome as a clinical variant.

Acyclovir↗

PubMed1994

Varicella-zoster virus (VZV) transcription during latency in human ganglia: construction of a cDNA library from latently infected human trigeminal ganglia and detection of a VZV transcript.

The entire varicella-zoster virus (VZV) genome appears to be present in latently infected human ganglia, but the extent of virus DNA transcription is unknown. Conventional methods to study virus gene transcripts by Northern (RNA) blotting are not feasible, since ganglia are small and VZV DNA is not abundant. To circumvent this problem, we prepared radiolabeled cDNA from ganglionic RNA, hybridized it to Southern blots containing VZV DNA, and demonstrated the presence of a transcript within the SalI C fragment of the virus genome (R. Cohrs, R. Mahalingam, A. N. Dueland, W. Wolf, M. Wellish, and D. H. Gilden, J. Infect. Dis. 166:S24-S29, 1992). To further map VZV transcripts, in the work described here we constructed a cDNA library from poly(A)+ RNA obtained from latently infected human ganglia. Phage DNA isolated from the library was used in PCR amplifications to detect VZV-specific inserts. The specificity of the PCRs was provided by selection of a primer specific for VZV gene 17, 18, 19, 20, or 21 and a second vector-specific primer. VZV gene 21-specific sequences were identified by PCR amplification. The PCR product contained the XhoI cloning site and poly(A)+ sequences between vector and VZV gene 21 sequences. The sequence motif at the 3' end of VZV gene 21, determined by cloning and sequencing of the PCR product, consisted of 49 to 51 nucleotide bases of 3'-untranslated DNA, the termination codon for the VZV gene 21 open reading frame, and DNA sequences reading into the VZV gene 21 open reading frame.

Aged↗

PubMed1994

Varicella-zoster virus myelitis: an expanding spectrum.

We report four cases of varicella-zoster virus (VZV)-associated myelopathy in adults. Myelopathy was remitting-exacerbating in two remarkable instances, once acute and once chronic. VZV myelopathy was diagnosed based on the close temporal relationship between rash and onset of myelopathy, and for the first time, by polymerase chain reaction, which revealed VZV DNA in the cerebral spinal fluid of three patients with pleocytosis weeks to months later. Magnetic resonance imaging was abnormal in three of four patients. Although all four patients were treated at some time with intravenous acyclovir, concomitant treatment with steroids and the presence of acquired immunodeficiency syndrome in one patient prevented conclusions about a favorable response to therapy. Myelopathy after VZV infection may be remitting-exacerbating in addition to acute or chronic. Detection of VZV DNA in cerebral spinal fluid months after rash was useful for diagnosis and suggests a role for virus in the pathogenesis of myelopathy.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Quantitation of latent varicella-zoster virus DNA in human trigeminal ganglia by polymerase chain reaction.

Competitive polymerase chain reaction was used to quantitate latent varicella-zoster virus (VZV) DNA in human trigeminal ganglia. Ganglionic DNA from five subjects was amplified with oligonucleotide primers specific for VZV gene 28. Two of the samples were also analyzed with primers specific for VZV gene 62. Our results indicated that there are 6 to 31 copies of the VZV genome in every 100,000 ganglionic cells.

Adult↗

PubMed1992

Localization of herpes simplex virus and varicella zoster virus DNA in human ganglia.

Human dorsal root ganglia from 14 randomly autopsied adults and 1 infant (all seropositive for both herpes simplex virus [HSV] and varicella zoster virus [VZV]) were examined for latent HSV-1 and VZV DNA by polymerase chain reaction. Thoracic ganglionic DNA from all subjects and trigeminal ganglionic DNA from 11 adults were analyzed. HSV-1 DNA was detected in trigeminal ganglia from 8 of 11 (73%) adults and in thoracic ganglia from 2 of 14 (14%) adults. VZV DNA was detected in trigeminal ganglia from 10 of 11 (91%) adults and in thoracic ganglia from 12 of 14 (86%) adults. None of the DNA samples were positive with primers specific for HSV-2. These findings indicate the presence of latent HSV-1 and VZV DNA in trigeminal ganglia and latent VZV DNA in thoracic ganglia of most seropositive adults. Furthermore, although HSV-1 latency most commonly develops in trigeminal ganglia, we also show for the first time the presence of HSV-1 latency in thoracic ganglia. Finally, both viruses can become latent in the same trigeminal ganglion.

Base Sequence↗

PubMed1992

Prevalence and distribution of latent simian varicella virus DNA in monkey ganglia.

We used polymerase chain reaction to analyze the prevalence and distribution of latent simian varicella virus (SVV) in ganglionic and nonganglionic tissues from nine African green monkeys experimentally infected with SVV. Primers specific for three different regions of the SVV genome were used for amplification. SVV DNA sequences were detected in trigeminal ganglia from seven of nine monkeys and in thoracic ganglia from seven of nine monkeys. Analysis of DNA from nonneuronal tissues of three monkeys and from adrenal glands of nine monkeys revealed the presence of SVV-specific sequences in the adrenal gland of one monkey. The results indicate that, like human varicella, SVV becomes latent primarily in ganglia at multiple levels of the neuraxis, and more than one region of the SVV genome is present in latently infected ganglia. SVV latency in primates may be a useful model for varicella latency in humans.

Animals↗