Biomedical subjects

M S Oberste

Publications and source records attributed to M S Oberste.

30 records · Page 2Linked to original sources

PubMed1997

Repeated emergence of epidemic/epizootic Venezuelan equine encephalitis from a single genotype of enzootic subtype ID virus.

Venezuelan equine encephalitis (VEE) epidemics and equine epizootics occurred periodically in the Americas from the 1920s until the early 1970s, when the causative viruses, subtypes IAB and IC, were postulated to have become extinct. Recent outbreaks in Columbia and Venezuela have renewed interest in the source of epidemic/epizootic viruses and their mechanism of interepizootic maintenance. We performed phylogenetic analyses of VEE virus isolates spanning the entire temporal and geographic range of strains available, using 857-nucleotide reverse transcription-PCR products including the E3 and E2 genes. Analyses indicated that epidemic/epizootic viruses are closely related to four distinct, enzootic subtype ID-like lineages. One of these lineages, which occurs in Columbia, Peru, and Venezuela, also included all of the epidemic/epizootic isolates; the remaining three ID-like lineages, which occur in Panama, Peru, Florida, coastal Ecuador, and southwestern Columbia, were apparently not associated with epizootic VEE emergence. Within the Columbia/Peru/Venezuela lineage, three distinct monophyletic groups of epidemic/epizootic viruses were delineated, indicating that VEE emergence has occurred independently at least three times (convergent evolution). Representative, complete E2 amino acid sequences were compared to identify potential determinants of equine virulence and epizootic emergence. Amino acids implicated previously in laboratory mouse attenuation generally did not vary among the natural isolates that we examined, indicating that they probably are not involved in equine virulence changes associated with VEE emergence. Most informative amino acids correlated with phylogenetic relationships rather than phenotypic characteristics, suggesting that VEE emergence has resulted from several distinct combinations of mutations that generate viruses with similar antigenic and equine virulence phenotypes.

Amino Acid Sequence↗

PubMed1997

Venezuelan equine encephalitis and Oropouche virus infections among Peruvian army troops in the Amazon region of Peru.

An outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during June 1994 among Peruvian army troops in Northern Peru. On June 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. A follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. Serum samples were tested for dengue (DEN), Oropouche (ORO), and Venezuelan equine encephalitis (VEE) IgM and IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). Virus isolation was performed by inoculation of newborn mice and Vero cell cultures. Viral isolates were identified by immunofluorescence, ELISA, and nucleotide sequencing. A VEE virus infection was confirmed in three of the eight febrile soldiers, two by virus isolation, and one by serology. Antigenic analysis indicated that one of the virus isolates was similar to VEE subtype I, variety ID, viruses previously isolated in Colombia and Venezuela. Nucleotide sequence data showed that both viral isolates were identical to one another and closely related to VEE ID viruses previously isolated in Peru, Colombia, and Venezuela. Serologic results showed that two of 26 afebrile soldiers had IgM antibody to VEE and four had IgG antibody to VEE; two febrile soldiers had IgG antibody in their first serum samples. Oropouche-specific IgM antibody was detected in one of the eight febrile and five of the afebrile soldiers, and 18 of the 34 soldiers had low titers of ORO IgG antibody titers, which did not meet the diagnostic criteria for confirmed cases. All soldiers were negative for DEN IgM antibody, and 10 had flavivirus IgG antibody that reacted with DEN antigens. These data indicated that VEE ID virus was one of the causes of illness among Peruvians soldiers and that this was the first association of this VEE subtype with human disease in Peru.

Adolescent↗

PubMed1996

Re-emergence of epidemic Venezuelan equine encephalomyelitis in South America. VEE Study Group.

BACKGROUND: Venezuelan equine encephalomyelitis (VEE) virus has caused periodic epidemics among human beings and equines in Latin America from the 1920s to the early 1970s. The first major outbreak since 1973 occurred in Venezuela and Colombia during 1995, and involved an estimated 75,000 to 100,000 people. We report an epidemiological and virological investigation of this epidemic. METHODS: Virus isolates were made in cell culture from human serum, human throat swabs, and brain tissue from aborted and stillborn human fetuses, as well as from horse brain tissue and pooled mosquito collections. Human sera were also tested for VEE-specific antibodies. The serotypes of VEE isolates were identified by antigen assays, and viruses were characterised genetically by sequencing PCR products generated from the E3 and E2 genes. Phylogenetic analyses were done to determine evolutionary relations with respect to previous epidemic/epizootic and enzootic VEE virus isolates. Mosquito collections were made to identify possible vectors, and clinical findings were determined by direct observation of patients visiting hospitals and clinics in affected regions, and by inspecting patient records. Equine vaccination and vector control were used in an attempt to halt the spread of the outbreak. FINDINGS: Most affected people had an acute, self-limited febrile illness of 3 to 4 days duration. However, convulsions were often seen in children, and abortions and fetal deaths occurred in pregnant women infected with VEE virus. Antigenic characterisation of 12 virus isolates spanning the temporal and spatial range of the outbreak indicated that all are VEE serotype IC. Phylogenetic analysis revealed that all of the 1995 viruses were closely related to serotype IC viruses isolated during a large VEE outbreak that occurred in the same regions of Colombia and Venezuela from 1962-1964. A 1983 mosquito isolate from north central Venezuela was also closely related to the 1995 isolates. INTERPRETATION: This outbreak was remarkably similar to one that occurred in same regions of Venezuela and Colombia during 1962-1964. Symptoms of infected patients, estimated mortality rates, meteorological conditions preceding the epidemic, and seasonal patterns of transmission were all very similar to those reported in the previous outbreak. In addition, viruses isolated during 1995 were antigenically and genetically nearly identifical to those obtained during 1962-1964. These findings suggest that the epidemic resulted from the re-emergence of an epizootic serotype IC VEE virus. Identification of a similar virus isolate in mosquitoes in Venezuela in 1983, 10 years after epidemic/epizootic VEE activity ceased, raises the possibility of a serotype IC enzootic transmission cycle in northern Venezuela.

Adolescent↗

PubMed1996

Complete sequence of Venezuelan equine encephalitis virus subtype IE reveals conserved and hypervariable domains within the C terminus of nsP3.

The complete nuleotide and predicted amino acid sequences of Venezuelan equine encephalitis (VEE) virus subtype IE (isolate 68U201) were determined and compared to those of other antigenic variants within the VEE complex, strains IAB-TrD, IC-P676, ID-3880, IE-Menall, and II-Fe3-7c. The 68U201 structural proteins were most closely related to their Menall counterparts (97--100% identity) and more distantly related to VEE strains of other antigenic varieties (83--93% identity). With the exception of nsP3, the 68U201 nonstructural proteins were 94--95% identical to those of TrD, P676, and 3880 (nonstructural gene sequences are not available for Menall and Fe3-7c). The amino-terminal region of nsP3 (aa 1--329), which is highly conserved among all alphaviruses, was 93--94% identical for all VEE strains. The nsP3 carboxyl region is highly divergent among alphaviruses in general, but well conserved among previously sequenced VEE strains (>90% identity). Surprisingly, the carboxyl region of 68U201 nsP3 (aa 330--563) was only 59--61% identical to that of subtype IAB, IC, and ID viruses, with large insertions and deletions in addition to numerous substitutions. The differences between the 68U201 and other VEE nsP3 carboxyl regions were not randomly distributed, as there were four domains of high similarity within the nonconserved region. To examine this divergence more closely, we sequenced a portion of the Menall ns3 gene. The 68U201 and Menall nsP3 nonconserved regions were 85.3% identical and had the same basic domain structure, which was distinct from the IAB, IC, and ID nsP3 proteins, suggesting that the domain structure of nsP3 may be subtype/variety-specific. VEE nsP3 sequence diversity may reflect ecological differences such as adaptation to different mosquito vectors or vertebrate hosts.

Amino Acid Sequence↗

PubMed1993

Characterization of bovine immunodeficiency virus rev cDNAs and identification and subcellular localization of the Rev protein.

One of the six putative accessory genes of bovine immunodeficiency virus (BIV) is similar to those identified as rev in the human immunodeficiency virus and visna virus genomes. To further analyze the BIV rev gene locus, protein, and function, rev cDNAs were cloned and characterized. BIV rev mRNA is derived from the full-length transcript by multiple splicing events and consists of three exons, including the untranslated leader sequence and two coding exons. BIV rev cDNA was expressed in bacteria and in a mammalian in vitro translation expression system. A 23-kDa Rev protein (p23rev) was immunologically detected in lysates from both systems by using an antiserum made to a synthetic Rev peptide. Recombinant p23rev made in bacteria was purified and used to make a polyvalent antiserum. Antisera to Rev peptide and recombinant p23rev immunoprecipitated p23rev from BIV-infected mammalian cells but not from virions. A mammalian expression vector using the BIV rev cDNA was constructed; p23rev was immunoprecipitated with anti-Rev serum from 32P-labeled lysates of monkey cells transfected with this plasmid, demonstrating that BIV Rev is phosphorylated. Immunofluorescence and immunoelectron microscopy with anti-BIV Rev antisera localized Rev in the nucleus and, particularly, in the nucleoli of BIV-infected cells. In functional studies, the expression of BIV Rev was shown to positively regulate the appearance both of Gag protein, which is translated from the unspliced primary viral transcript, and of singly spliced env mRNA but not that of the multiply spliced tat mRNA. These results demonstrate that BIV Rev activity correlates with the known function of lentivirus Rev proteins.

Amino Acid Sequence↗

PubMed1992

Conservation of amino-acid sequence motifs in lentivirus Vif proteins.

The nonstructural/regulatory genes of human immunodeficiency virus type 1 (HIV-1) and other lentiviruses are believed to play an important role in the replication and pathogenesis of these viruses. In HIV-1 and other lentiviruses, the vif (viral infectivity factor) open reading frame (ORF) (also termed sor or Q in some lentivirus genomes) is located in the central region, overlapping the 3' end of the pol ORF, but in a different reading frame. Among the lentiviruses, only equine infectious anemia virus lacks a vif ORF. The predicted Vif protein sequences from 38 lentiviruses were analyzed for the presence of global and local sequence similarity. The Vif proteins of closely related lentiviruses are highly conserved (HIV-1HXB2:HIV-1mn = 91% identity), while those of more distantly related lentirviruses have diverged significantly (HIV-1HXB2:simian immunodeficiency virusmax = 30% identity). A search for local sequence similarity revealed that a unifying feature of predicted lentivirus Vif proteins is the presence of at least one of two short, highly conserved sequence motifs, SL(I/V)X4YX9Y and SLQXLA. SLQXLA was present in 34 of 38 lentiviruses examined, while the remaining four lentiviruses had one (three viruses) or two (one virus) substitutions in this motif (of five total substitutions, three were conservative changes). The SL(I/V)X4YX9Y motif was found only in primate lentiviruses and in bovine immunodeficiency-like virus. Based on these findings, we suggest that the locus designation vif be used to denote all lentivirus ORFs previously called vif, Q, or sor.

Amino Acid Sequence↗

PubMed1992

Persistent infection of rabbits with bovine immunodeficiency-like virus.

Chronic infection of rabbits was induced by a single intraperitoneal injection of bovine immunodeficiency-like virus (BIV)-infected cells. Ten BIV-infected animals were monitored serologically for up to 2 years. Results of serologic and virus rescue assays indicated that all animals became infected and demonstrated a rapid and sustained BIV-specific humoral response. BIV was rescued by cocultivation from spleen, lymph nodes, and peripheral blood leukocytes of infected animals. Viral DNA in immune tissues was confirmed by polymerase chain reaction amplification of BIV sequences. These data and specific immunohistochemical staining of mononuclear cells of the spleen for BIV antigen suggest that the infection is targeted to immune system cells.

Animals↗

PubMed1991

Analysis of the transcription pattern and mapping of the putative rev and env splice junctions of bovine immunodeficiency-like virus.

The bovine immunodeficiency-like virus (BIV) genome contains the obligatory structural genes of all retroviruses and, in addition, the complex central region of lentiviruses; this novel region may code for at least five nonstructural/regulatory genes in BIV (K.J.Garvey, M.S. Oberste, J.E. Elser, M.J. Braun, and M.A. Gonda, Virology 175:391-409, 1990). As a prelude to determining the function of these novel open reading frames, the transcriptional pattern of BIV was studied by Northern analysis of RNA from BIV-infected cells. Five size classes of BIV-specific RNAs of 8.5, 4.1, 3.8, 1.7, and 1.4 kb were detected. The 8.5-kb RNA contains sequences from all regions of the genome; it is the virion RNA and probably serves as the gag-pol transcript as well. By using gene-specific probes, subgenomic viral RNAs of 3.8, 1.7, and 1.4 kb were tentatively identified as the env, tat, and rev spliced messages, respectively. The 4.1-kb RNA could not be unambiguously identified but may encode vif. The hybridization patterns of the putative tat and rev mRNAs suggest that they are the products of multiple splicing events. Discrete transcripts for the BIV W and Y central region open reading frames were not defined. The characterization of partial cDNA clones has permitted the mapping of the env and putative rev splice junctions.

Amino Acid Sequence↗

PubMed1990

Nucleotide sequence and genome organization of biologically active proviruses of the bovine immunodeficiency-like virus.

The complete nucleotide sequences and translations of major open reading frames (ORF) of two distinct, infectious, proviral molecular clones (106 and 127) of the bovine immunodeficiency-like virus (BIV), obtained from a single virus isolation, were determined and compared. The genomes of BIV 127 and 106 are 8482 and 8391 nucleotides (nt), respectively, in the form predicted for the viral RNA. The structural organization of the genomes of BIV 127 and 106 are identical to one another and most similar to that of the lentivirus subfamily of retroviruses. In addition to gag, pol, and env genes, the BIV genome contains five short ORFs between and overlapping pol and env in the "central region," a hallmark of the lentiviruses which is believed to play an important role in their pathogenesis. Three of the short ORFs in the central region of BIV have been identified by location and structural similarity to the nonstructural/regulatory genes (vif, tat, and rev) of other lentiviruses; we also discovered two unique ORFs, termed W and Y, which may serve as exons for novel genes. BIV does not have the nef gene found in primate lentivirus genomes. The proviral LTR of BIV 127 is 589 nt, contains regulatory signals for initiation, enhancement, and termination of viral transcription, and has sequences related to the Sp1 and NF-kappa B binding sites. A major deletion (87 nt) in the env gene and 2 minor deletions (2 nt each) in the R regions of the LTRs account for the smaller size of clone 106. Numerous point mutations were also present; some caused coding substitutions that were most prevalent in the env encoding ORF. These data suggest that, within a single virus isolate, BIV displays extensive genomic variation. These infectious clones of BIV represent well-defined tools with which to analyze the function of the various ORFs and to dissect the molecular mechanisms of replication and pathogenesis.

Amino Acid Sequence↗

PubMed1990

Development of the bovine immunodeficiency-like virus as a model of lentivirus disease.

The bovine immunodeficiency-like virus (BIV) is morphologically, serologically, and genetically related to the lentivirus subfamily of retroviruses which includes human and simian immunodeficiency viruses and other lentiviruses causally associated with debilitating diseases of domestic animals. There are many parallels in the biology and pathologic characteristics of BIV infections with those of HIV that make its development as a model of HIV-like infection and disease potentially attractive. In order to obtain a better understanding of the molecular basis of BIV-induced disease, two biologically active proviruses of BIV were molecularly cloned and sequenced. The BIV genome is 9.0 kilobases in the form of the proviral DNA. It contains the obligate retroviral structural genes, gag, pol, and env. In addition, in the BIV central region, between and overlapping pol and env, there are five potential coding regions for non-structural/regulatory genes; three are analogous to vif, tat, and rev in HIV and two, called W and Y, are unique to BIV. There is no coding region analogous to nef in BIV. Sequence comparisons of two functional proviruses obtained from the DNA of cells carrying an infection from a single virus isolation indicate that the genome of BIV is highly variable within a single biological isolate. Moreover, the greatest number of substitutions occur in the env gene. The results suggest the presence of multiple genotypes which may be of significance in defining the disease potential of a BIV isolate. These clones will be useful in dissecting the replicative cycle and mechanisms of pathogenesis of BIV in various animal models.

Amino Acid Sequence↗

PubMed1988

Measurement of poliovirus RNA polymerase binding to poliovirion and nonviral RNAs using a filter-binding assay.

The binding of the purified poliovirus RNA-dependent RNA polymerase to viral and nonviral RNAs was studied using a protein-RNA nitrocellulose filter binding assay. A cellular poly(A)-binding protein was found in viral polymerase preparations, but was easily separated from the polymerase by chromatography on poly(A) Sepharose. Optimal conditions for the binding of purified polymerase (fraction 5-PAS) to 32P-labeled poliovirion RNA were determined. The binding of purified polymerase to 32P-labeled ribohomopolymeric RNAs was examined, and the order of binding observed was poly(G) much much greater than poly(U) greater than poly(C) greater than poly(A). In competitive binding studies, the polymerase bound with equal efficiency to virion RNA and to a subgenomic transcript which contained the 3' end of the genome. The polymerase bound to 18S ribosomal RNA and to globin mRNA equally well, but with a five-fold lower affinity than to virus-specific RNAs. The results suggest that the polymerase exhibits sequence specificity in binding and that polymerase binding sites in poliovirus RNA may contain (G- and/or U)-rich sequences.

DNA-Directed RNA Polymerases↗

PubMedDate not supplied

A cluster of fulminant myocarditis cases in children, Baltimore, Maryland, 1997.

The true incidence of myocarditis in children is difficult to estimate because many mild cases go undetected. This study describes an unusual cluster of myocarditis cases that occurred in young children living in the greater Baltimore area between May and October 1997. A search of multiple comprehensive databases and interviews with area pediatric cardiologists were conducted to identify unreported cases and determine the background rate of myocarditis in the area. Seven cases of myocarditis were found as well as two with a similar clinical picture and myocardial fibrosis on tissue examination. Six case patients with active myocarditis and one child with fibrosis died. The case children were predominantly black (eight of nine) and male (seven of nine), with no identifiable risk factors. The disease was characterized by a fulminant course with malignant arrhythmias. The greatest number of pediatric myocarditis deaths reported in 1 year prior to 1997 was three. Myocardial tissues were examined using immunohistochemistry, in situ hybridization, and polymerase chain reaction but no etiologic agent was identified. This outbreak is unusual because of both the number of cases and the fulminant course of the disease in this group of children.

Arrhythmias, Cardiac↗