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PubMed1994

[Sjögren's syndrome and virus].

Virus are suspected to play a role in triggering lymphoid proliferation observed in Sjögren's syndrome (SS). In this paper, attention is focused on the potential role of herpes virus, retrovirus and hepatitis C virus (HCV) in the pathogenesis of SS. Genes and proteins of Epstein-Barr virus (EBV) are detected in epithelial cells of salivary or lacrymal glands more often in SS patients than in controls. However, it could just be a consequence of the destruction of the glands by another mechanism. Endogenous retroviral sequences are detected with a high frequency in salivary glands of SS patients, than in controls. Sicca syndrome may occur in HIV, HTLV-I and HCV-infected patients. We found the expression of the tax gene of HTLV-I in epithelial cells of salivary glands from two patients without any evidence of HTLV-I-associated disease and without any seric anti-HTLV-I antibodies. Anti-SSA and anti-SSB antibodies are usually not detected in serum of patients with sicca syndrome occurring during evolution of recognized viral diseases. Thus, this kind of sicca syndrome could be a little different from classical auto-immune SS. However, it is tempting to consider oropharynx like a site of latency of a lot of virus which could infect salivary epithelial cells. In some people with a particular genetic background, this could lead to a lymphoid proliferation and, secondary, to the destruction of the glands.

Animals↗
PubMed1998

A prophylactic and therapeutic AIDS vaccine containing as a component the innocuous Tat toxoid.

Extracellular Tat can act as a viral toxin on uninfected cells of different tissues, including the CNS and the immune system, thus in order to immunize humans against Tat we have prepared a biologically inactivated but immunogenic Tat (Tat Toxoid). Tat Toxoid is not toxic in mice even at high doses. It triggers high levels of specific Tat Abs in the mouse and rabbit. Furthermore, in humans Tat Toxoid immunization was safe and induced in seronegatives persistent high levels of Tat Abs and in immunodeficient patients a significant rise of these specific Abs. Facing acute HIV-1 infection, the presence of high level of circulating Tat Abs promoted by Tat Toxoid vaccine should prevent Tat-induced immunosuppression and allow anti-HIV-1 cellular response to develop. As a consequence, early release of beta-chemokines could enhance host resistance towards HIV-1, and, in infected people, inhibit viral replication and evolution towards AIDS.

AIDS Vaccines↗
PubMed2000

Nitric oxide and virus infection.

Nitric oxide (NO) has complex and diverse functions in physiological and pathophysiological phenomena. The mechanisms of many events induced by NO are now well defined, so that a fundamental understanding of NO biology is almost established. Accumulated evidence suggests that NO and oxygen radicals such as superoxide are key molecules in the pathogenesis of various infectious diseases. NO biosynthesis, particularly through expression of an inducible NO synthase (iNOS), occurs in a variety of microbial infections. Although antimicrobial activity of NO is appreciated for bacteria and protozoa, NO has opposing effects in virus infections such as influenza virus pneumonia and certain other neurotropic virus infections. iNOS produces an excessive amount of NO for long periods, which allows generation of a highly reactive nitrogen oxide species, peroxynitrite, via a radical coupling reaction of NO with superoxide. Thus, peroxynitrite causes oxidative tissue injury through potent oxidation and nitration reactions of various biomolecules. NO also appears to affect a host's immune response, with immunopathological consequences. For example, overproduction of NO in virus infections in mice is reported to suppress type 1 helper T-cell-dependent immune responses, leading to type 2 helper T-cell-biased immunological host responses. Thus, NO may be a host response modulator rather than a simple antiviral agent. The unique biological properties of NO are further illustrated by our recent data suggesting that viral mutation and evolution may be accelerated by NO-induced oxidative stress. Here, we discuss these multiple roles of NO in pathogenesis of virus infections as related to both non-specific inflammatory responses and immunological host reactions modulated by NO during infections in vivo.

Humans↗
PubMed1991

Characterization of bovine papillomavirus E1 region deletion mutants associated with neoplastic transformation in a murine cell line.

Spontaneous focus formation in the contact-inhibited C127 cell line, cl.2, harbouring multiple copies of a bovine papillomavirus type 1 deletion mutant, was associated with the evolution of further viral genomic deletions in addition to an amplification of the viral genome copy number. Three simple frameshift deletions of 308, 605 and 1291 bp, associated with separate transformation events, were mapped within the E1 open reading frame, implying a common mechanism of spontaneous transformation in this cell line. Furthermore, each transformed cell line also retained multiple copies of the intact E1 gene, suggesting that these novel deletion mutants might function by a dominant-negative mechanism to disrupt the normal control of viral DNA replication or viral transcription. These mutants had the potential to encode truncated E1 polypeptides with a common N-terminal region encoded by the 5' end of E1, i.e. overlapping the previously described E1 modulator gene. A possible role for these mutants in diverting a lethal type of virus-cell interaction is discussed.

Animals↗
PubMed2000

Isolation and complete nucleotide sequence of a Chinese Sindbis-like virus.

Infection with alphaviruses is common in the Chinese population. Here we report the isolation of a Sindbis-like virus from a pool of Anopheles mosquitoes collected in Xinjiang, China during an arbovirus survey. This virus, designated XJ-160, rapidly produced cytopathic effects on mosquito and hamster cells. In addition, it was lethal to neonatal mice if inoculated intracerebrally. Serologically, XJ-160 reacted with and was neutralized by an anti-Sindbis antibody. Anti-XJ-160 antibodies were found in several cohorts of Chinese subjects. The complete 11626-base nucleotide sequence of XJ-160 was determined. XJ-160 has diverged significantly from the prototype Sindbis virus, with an 18% difference in nucleotide sequence and an 8.6% difference in amino acids; there are 11 deletions and 2 insertions, involving 99 nucleotides in total. XJ-160 is most closely linked to Kyzylagach virus isolated in Azerbaijan. Both belong to the African/European genetic lineage of Sindbis virus, albeit more distantly related to other members.

Alphavirus Infections↗
PubMed1981

Distribution of bacteriophage phi 3T homologous deoxyribonucleic acid sequences in Bacillus subtilis 168, related bacteriophages, and other Bacillus species.

The Bacillus subtilis 168 chromosome was found to share extensive homology with the genome of bacteriophage phi 3T. At least three different regions of the bacterial genome hydridized to ribonucleic acid complementary to phi 3T deoxyribonucleic acid (DNA). The thymidylate synthetase gene, thyA, of B. subtilis and the sequences adjacent to it were shown to be homologous to the region in the phi 3T DNA containing the phage-encoded thymidylate synthetase gene, thyP3. SP beta, a temperate bacteriophage known to be integrated into the B. subtilis 168 chromosome, was demonstrated to be closely related to phi 3T. Other regions of the bacterial genome were also found to hybridize to the phi 3T probe. The nature and location of these sequences in the bacterial and phage chromosomes were not identified. It was shown however, that they were not homologous to either the thyP3 gene or the DNA surrounding the thyP3 gene. The chromosomes of other Bacillus species were also screened for the presence of phi 3T homologous sequences, and the thyP3 gene was localized in the linear genomes of phages phi 3T and rho 11 by heteroduplex mapping. It is suggested that the presence of sequences of phage origin in the B. subtilis 168 chromosome might contribute to the restructuring and evolution of the viral and bacterial DNAs.

Bacillus↗
PubMed1981

Enhanced mutability associated with a temperature-sensitive mutant of vesicular stomatitis virus.

Temperature-sensitive (ts) mutant tsD1 of vesicular stomatitis virus, New Jersey serotype, is the sole representative of complementation group D. Clones derived from this mutant exhibited three different phenotypes with respect to electrophoretic mobility of the G and N polypeptides of the virion in sodium dodecyl sulfate-polyacrylamide gel. Analysis of non-ts pseudorevertants showed that none of the three phenotypes was associated with the temperature sensitivity of mutant tsD1. Additional phenotypes, some also involving the NS polypeptide, appeared during sequential cloning, indicating that mutations were generated at high frequency during replication of tsD1. Furthermore, mutations altering the electrophoretic mobility of the G, N, NS, and M polypeptides were induced in heterologous viruses multiplying in the same cells as tsD1. These heterologous viruses included another complementing ts mutant of vesicular stomatitis virus New Jersey and ts mutants of vesicular stomatitis virus Indiana and Chandipura virus. Complete or incomplete virions of tsD1 appeared to be equally efficient inducers of mutations in heterologous viruses. Analysis of the progeny of a mixed infection of two complementing ts mutants of vesicular stomatitis virus New Jersey with electrophoretically distinguishable G, N, NS, and M proteins yielded no recombinants and excluded recombination as a factor in the generation of the electrophoretic mobility variants. In vitro translation of total cytoplasmic RNA from BHK cells indicated that post-translational processing was not responsible for the aberrant electrophoretic mobility of the N, NS, and M protein mutants. Aberrant glycosylation could account for three of four G protein mutants, however. Some clones of tsD1 had an N polypeptide which migrated faster in sodium dodecyl sulfate-polyacrylamide gel than did the wild type, suggesting that the polypeptide might be shorter by about 10 amino acids. Determination of the nucleotide sequence to about 200 residues from each terminus of the N gene of one of these clones, a revertant, and the wild-type parent revealed no changes compatible with synthesis of a shorter polypeptide by premature termination or late initiation of translation. The sequence data indicated, however, that the N-protein mutant and its revertant differed from the parental wild type in two of the 399 nucleotides determined. These sequencing results and the phenomenon of enhanced mutability associated with mutant tsD1 reveal that rapid and extensive evolution of the viral genome can occur during the course of normal cytolytic infection of cultured cells.

Animals↗
PubMed1997

Genetic exchange by recombination or reassortment is infrequent in natural populations of a tripartite RNA plant virus.

Two hundred seventeen field isolates of cucumber mosaic cucumovirus (CMV), sampled from 11 natural populations, were typed by RNase protection assay (RPA) using probes from the genomic RNAs of strains in subgroup I and in subgroup II of CMV strains. Most (85%) of the analyzed isolates belonged to subgroup I. For these subgroup I isolates, only two clearly different RPA patterns, A and B, were found for each of four probes representing RNA1, RNA2, and each of the two open reading frames in RNA3. On the basis of these RPA patterns for each probe, different haplotypes were defined. The frequency composition for these haplotypes differed for the various analyzed populations, with no correlation with place or year of sampling. This genetic structure corresponds to a metapopulation with local extinctions and recolonizations. Most subgroup I isolates (73%) belonged to haplotypes with RPA pattern A (type 1) or B (type 2) for all four probes. A significant fraction of subgroup I isolates (16%) gave evidence of mixed infections with these two main types, from which genetic exchange could occur. Genetic exchange by segment reassortment was seen to occur: the fraction of reassortant isolates was 4%, reassortment did not occur at random, and reassortants did not become established in the population. Thus, there is evidence of selection against reassortment between types 1 and 2 of subgroup I isolates. Aphid transmission experiments with plants doubly infected with type 1 and type 2 isolates gave further evidence that reassortment is selected against in CMV. Genetic exchange by recombination was detected for RNA3, for which two RPA probes were used. Recombinant isolates amounted to 7% and also did not become established in CMV populations. Sequence analyses of regions of RNA1, RNA2, and RNA3 showed that there are strong constraints to maintain the encoded sequence and also gave evidence that these constraints may have been different during divergence of types 1 and 2 and, later on, during diversification of these two types. Constraints to the evolution of encoded proteins may be related to selection against genetic exchange. Our data, thus, do not favor current hypotheses that explain the evolution of multipartite viral genomes to promote genetic exchange.

Genome, Viral↗
PubMed1999

Human herpesvirus 6 open reading frame U83 encodes a functional chemokine.

Some viruses including herpesviruses have undergone evolution to benefit viral infection and propagation by pirating and modifying host genes such as chemokine genes. Human herpesvirus 6 (HHV-6), acutely or persistently infects mononuclear cells in vitro. DNA sequence analysis of HHV-6 has revealed that the putative protein encoded by an open reading frame (ORF) of the U83 gene in HHV-6 variant B resembled a human chemokine. We have cloned the U83 gene and analyzed the biological function of this gene. The U83 gene contained an ORF encoding a 113-amino-acid peptide, starting at the first methionine and containing a possible signal peptide and the typical cysteine residues characteristic of the chemokines. Reverse transcription-PCR analysis of mRNA and immunofluorescent-antibody testing of infected cells both indicated that the encoded protein was a late protein. The ORF U83 gene fused to the Fc gene was expressed as a fusion protein in COS-7 cells by transfection, and the fusion protein was purified from the supernatant of transfected cells to test its biological function. The purified protein was capable of inducing transient calcium mobilization in THP-1 cells and of chemotactically activating THP-1 cells. These findings suggested that the U83 protein might play an important role in HHV-6 propagation in vivo by activating and trafficking mononuclear cells to sites of viral replication, thus aiding the development of superbly efficient virus production mechanisms.

Amino Acid Sequence↗
PubMed2004

Genomically intact endogenous feline leukemia viruses of recent origin.

We isolated and sequenced two complete endogenous feline leukemia viruses (enFeLVs), designated enFeLV-AGTT and enFeLV-GGAG. In enFeLV-AGTT, the open reading frames are reminiscent of a functioning FeLV genome, and the 5' and 3' long terminal repeat sequences are identical. Neither endogenous provirus is genetically fixed in cats but polymorphic, with 8.9 and 15.2% prevalence for enFeLV-AGTT and enFeLV-GGAG, respectively, among a survey of domestic cats. Neither provirus was found in the genomes of related species of the Felis genus, previously shown to harbor enFeLVs. The absence of mutational divergence, polymorphic incidence in cats, and absence in related species suggest that these enFeLVs may have entered the germ line more recently than previously believed, perhaps coincident with domestication, and reopens the question of whether some enFeLVs might be replication competent.

Animals↗
PubMed2025

Whole genome sequencing and phylogenetic classification accelerate the implementation of respiratory syncytial virus genomic surveillance in Canada: a pilot study.

UNLABELLED: Whole genome sequencing (WGS) has emerged as a powerful tool to facilitate the study of existing and emerging infectious diseases. WGS-based genomic surveillance provides information on the genetic diversity and tracks the evolution of important viral pathogens, including respiratory syncytial virus (RSV). Multiplex tiling polymerase chain reaction (PCR) assays have been used to facilitate sequencing of a variety of pathogens in support of genomics-based surveillance initiatives. We developed, optimized, and implemented multiplex tiling PCR assays for RSVA and RSVB capable of generating near-complete genomes in the majority of contemporaneous specimens tested. A pilot data set comprising 52 RSVA and 37 RSVB genomes derived from Canadian clinical specimens during the 2022-2023 respiratory virus season was used to perform phylogenetic analyses using both near-complete genome and glycoprotein (G) sequences. Overall, the RSV phylogenetic tree built with whole genomes showed identical lineage clusters as compared to the G gene but was more discriminatory. Moreover, the availability of complete genomes enables the identification of a broader range of mutations. For instance, mutations identified in the fusion protein among Canadian isolates tested here, including S377N, K272M, S276N, S211N, S206I, and S209Q, could affect the efficacy of current vaccines or antiviral-based therapeutics. In conclusion, our work reinforces other recent studies demonstrating the utility of multiplex tiling PCR assays to facilitate high-throughput WGS of RSV, which is capable of supporting enhanced genomic surveillance initiatives, as well as the more comprehensive genomic analyses required to inform public health strategies for the development and usage of vaccines and antiviral drugs. IMPORTANCE: We present assays to efficiently sequence genomes of RSVA and RSVB. This enables researchers and public health agencies to acquire high-quality genomic data using rapid and cost-effective approaches. Genomic data-based comparative analysis can be used to conduct surveillance and monitor circulating isolates for efficacy of vaccines and antiviral therapeutics.

Humans↗
PubMed1992

Acute sensory and autonomic neuropathy: possible association with coxsackie B virus infection.

This report describes a 26 year old woman with a Coxsackie B virus infection complicated by an acute pandysautonomic and sensory neuropathy. Electrophysiological studies suggested an axonal neuropathy. A sural nerve biopsy performed early in the disease showed axonal degeneration with a virtual absence of unmyelinated fibres and moderate loss of myelinated fibres, mainly affecting the small fibres; this differs from previous reports. An immune-mediated or direct virus action might explain the pathogenesis of this unusual evolution of a viral infection.

Adult↗
PubMedDate not supplied

[Fulminant acute hepatitis treated by immunologic therapy (author's transl)].

Following the most recent results on immunological pathogenetic mechanism, on which seems to be based the malignant evolution of acute viral hepatitis the AA. have treated a patient affected of acute fulminant hepatitis by means of immunologic therapy with specific globulins anti-HBsAg. The result of this personal experience and the analysis of the data from the literature suggest the opportunity to use specific antibodies (HBsAb) associated with syntomatic and depurative therapies, with obvious limits of single experience.

Acute Disease↗
PubMedDate not supplied

Approximate formulae (deduced from a mathematical model) for the characteristics of the interepidemic and epidemic periods of some virus diseases.

By a qualitative analysis of the solutions of the mathematical model equations (describing the morbidity and susceptibility evolution in a viral epidemics), approximate formulae for the extreme values of the variables and for the duration of the main phases of a multiannual cycle are deduced. These formulae were validated by numerical simulation of the solutions, leading to the exact values of the mentioned essential characteristics of the diseases propagation.

Disease Outbreaks↗
PubMedDate not supplied

[Distribution of subtypes of viral hepatitis B antigen in areas of Rumania].

The results of subtyping the B antigen in 551 sera from patients with viral hepatitis, chronic evolutive hepatitis and cirrhosis, chronic carriers, donors and healthy subjects, were confirmed as positive HBAg by diffusion in agar, counterelectrophoresis and radioimmunology, and characterized by the d-y and w-r determinants by rheophoresis. The high incidence of the y determinant in all nine counties investigated probably reflects the prevalence of this serotype in Romania, recalling the distribution of subtypes observed in the south of Europe.

Adolescent↗
PubMed2004

[Emergence of new viruses in Asia: is climate change involved?].

Tropical Africa is not the only area where deadly viruses have recently emerged. In South-East Asia severe epidemics of dengue hemorrhagic fever started in 1954 and flu pandemics have originated from China such as the Asian flu (H2N2) in 1957, the Hong-Kong flu (H3N2) in 1968, and the Russian flu (H1N1) in 1977. However, it is especially during the last ten years that very dangerous viruses for mankind have repeatedly developed in Asia, with the occurrence of Alkhurma hemorrhagic fever in Saudi Arabia (1995), avian flu (H5N1) in Hong-Kong (1997), Nipah virus encephalitis in Malaysia (1998,) and, above all, the SARS pandemic fever from Southern China (2002). The evolution of these viral diseases was probably not directly affected by climate change. In fact, their emergential success may be better explained by the development of large industry poultry flocks increasing the risks of epizootics, dietary habits, economic and demographic constraints, and negligence in the surveillance and reporting of the first cases.

Africa↗
PubMedDate not supplied

[Cellular mediated immunity in virus infections].

The intervention of cellular immunity in the course of specific antiviral defence is suggested or confirmed by a series of clinical and experimental findings, i.e. the evolution of certain viral diseases following a second contact with viral antigens; discrepancy between the level of antiviral serum antibodies and the clinical course of some viral diseases; pathohistological alterations in some viral diseases, suggesting the intervention of cellular immunity; the clinical aspects of natural or experimental viral diseases in primary and secondary immunodeficiency. Investigations were likewise carried out on certain indices of cellular immunity in human or experimental viral diseases, such as delayed hypersensitivity skin tests; the transfer of immune lymphocytes; lymphocytic blastic transformation; inhibition of macrophage migration; specific cytotoxicity test. The problems concerning the role of cellular immunity in the specific defence against viruses may be grouped as follows: mechanisms of induction of the immune cellular response in viral infections; relationship between cellular and humoral immunity in antiviral resistance; relative independance of systemic and local cellular immunity in the course of viral diseases; the cellular basis of cellular mediated immunity in viral diseases.

Animals↗