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At least 703 records · Page 39Linked to original sources
PubMed2003

Mapping epitopes in equine rhinitis A virus VP1 recognized by antibodies elicited in response to infection of the natural host.

Equine rhinitis A virus (ERAV) is an important respiratory pathogen of horses and is of additional interest because of its close relationship and common classification with foot-and-mouth disease virus (FMDV). As is the case with FMDV, the VP1 capsid protein of ERAV has been shown to be a target of neutralizing antibodies. In FMDV VP1, such antibodies commonly recognize linear epitopes present in the betaG-betaH loop region. To map linear B cell epitopes in ERAV VP1, overlapping fragments spanning its length were expressed in Escherichia coli as glutathione S-transferase (GST) fusion proteins. These fusion proteins were tested for reactivity with sera from ERAV-infected horses and with polyclonal sera from ERAV-immunized rabbits and mice. Regions at the N- and C-termini as well as the betaE-betaF and the betaG-betaH loop regions contained B cell epitopes that elicited antibodies in the natural host. GST fusion proteins of these regions also elicited antibodies following immunization of rabbits and mice, which, in general, strongly recognized native ERAV VP1 but which were non-neutralizing. It is concluded that the N-terminal region of ERAV VP1, in particular, contains strong B cell epitopes.

Amino Acid Sequence↗
PubMed2005

Review of the temporal and geographical distribution of measles virus genotypes in the prevaccine and postvaccine eras.

Molecular epidemiological investigation of measles outbreaks can document the interruption of endemic measles transmission and is useful for establishing and clarifying epidemiological links between cases in geographically distinct clusters. To determine the distribution of measles virus genotypes in the prevaccine and postvaccine eras, a literature search of biomedical databases, measles surveillance websites and other electronic sources was conducted for English language reports of measles outbreaks or genetic characterization of measles virus isolates. Genotype assignments based on classification systems other than the currently accepted WHO nomenclature were reassigned using the current criteria. This review gives a comprehensive overview of the distribution of MV genotypes in the prevaccine and postvaccine eras and describes the geographically diverse distribution of some measles virus genotypes and the localized distributions of other genotypes.

Genotype↗
PubMed2006

Control and eradication strategies of avian influenza in Mexico.

In December 1994, a highly pathogenic (HP) avian influenza (AI) outbreak occurred in Mexico, caused by the subtype H5N2, affecting two main regions of egg and poultry-meat production. At that time, governmental actions included immediate stamping out of the affected flocks, disinfection of affected premises, quarantine measures in the region, strict movement controls on poultry and their products and vaccination. With these policies, the disease was eradicated in a relatively short time. The last case of HPAI was detected in June 1995 and the country was declared as free of HPAI virus in January 1996 to the World Animal Health Organisation (OIE). Since then, Mexico has maintained a control programme against low pathogenic (LP) AI virus that is based on a zoning classification, movement controls and other strategies.

Animals↗
PubMed2006

TBE incidence versus virus prevalence and increased prevalence of the TBE virus in Ixodes ricinus removed from humans.

Traditionally, the classification of risk areas of tick-borne encephalitis (TBE) is based on the recording of autochthonous cases of the disease. In Germany, an extension of these areas over the years and an increasing virus prevalence in ticks have been observed in recent years. Registration of foci with autochthonous TBE cases, recording of disease incidence and virus prevalence in ticks are all proven epidemiological methods to characterize TBE risk areas. These data are necessary for a scientifically proven recommendation of TBE vaccines, and they need to be updated regularly. These epidemiological methods have advantages and disadvantages with respect to the risk assessment of TBE areas. Despite the fact that these methods are suitable for risk assessment in practice, disease incidence (new cases per year/100,000 inhabitants) and virus prevalence in questing ticks did not correlate. Using nested RT-PCR we were able to demonstrate that the prevalence of TBE virus (TBEV) in ticks removed from humans was significantly higher than in unfed, free-living Ixodes ricinus of the same area. The 561 ticks collected from humans in doctors' surgeries in Bavaria in 2002 were examined by nRT-PCR. The estimated overall virus prevalence in tested ticks was 8.8% (95% CI: 6.45-11.57%). The removed ticks examined were classified according to the sites of exposure of the patients in the individual districts. Peak values were measured in the district of Regen with 20.6% and in the district of Freyung-Grafenau with 18.3%. In recent studies on unfed I. ricinus (nymphs, adults), the average TBEV prevalence in ticks in Bavarian risk areas was between 0.5% and 2%.

Animals↗
PubMed1982

Types of avian infectious bronchitis strains isolated in Quebec.

Between 1976 and 1980, 24 isolates of infectious bronchitis virus were obtained from Quebec flocks. The serological classification of these isolates was demonstrated by cross neutralization tests using antisera to 13 different reference virus strains. Of the 24 isolates, ten were identified as Connecticut, six Holland and one SE-17 types. Seven strains did not react with any of the specific antisera.

Animals↗
PubMed2004

Distinctive sequence characteristics of subgenotype A1 isolates of hepatitis B virus from South Africa.

Phylogenetic analysis of hepatitis B virus (HBV) has led to its classification into eight genotypes, A to H. The dominant genotype in South Africa is genotype A, which consists of two subgenotypes, A1 and A2. Subgenotype A1 (previously subgroup A') predominates over subgenotype A2 (previously subgroup A minus A'). The complete genome of HBV isolated from 18 asymptomatic carriers of the virus and five acute hepatitis B patients was amplified; the resulting amplicons were cloned and sequenced. All acute hepatitis isolates belonged to subgenotype A1 and had no distinguishing mutations relative to the isolates from asymptomatic carriers, which had a distribution of ten subgenotype A1, two subgenotype A2 and six genotype D. The presence of the previously described amino acid residues that distinguish subgenotype A1 (subgroup A') from the remainder of genotype A in the S and polymerase genes was confirmed. Moreover, the large number of subgenotype A1 isolates sequenced allowed identification in the other open reading frames of additional nucleotide and amino acid changes that are characteristic of subgenotype A1. In particular, nucleotide mutations at positions 1809-1812 that alter the Kozak sequence of the precore/core open reading frame, and A(1888) in the precore region, were found exclusively in subgenotype A1 isolates. Unique sequence alterations of the transcriptional regulatory elements were also found in subgenotype A1 isolates. The mean nucleotide divergence of subgenotype A1 was greater than that of subgenotype A2, suggesting that this subgenotype has been endemic for a longer time in the South African black population than had subgenotype A2.

Carrier State↗
PubMed1996

Bovine adenovirus type 10: properties of viruses isolated from cases of bovine haemorrhagic enterocolitis.

The isolation, serological classification and growth properties of adenoviruses isolated from fatal cases of haemorrhagic enterocolitis in calves are described. Four viruses, from different submissions, were isolated in cultures of calf testis cells and were identified as adenoviruses by electron microscopy. The four isolates were serologically identical and were classified as bovine adenovirus type 10 in cross-neutralisation tests with other bovine, ovine and porcine adenovirus species. Their growth in the nucleus of infected cells was accompanied by the production of typical adenovirus-associated inclusions. A serological survey to determine the incidence of infection with the virus in cattle in Northern Ireland demonstrated the presence of low levels of neutralising antibodies in 55 per cent of cattle over two years old, although only 8 per cent were positive at a 1/500 dilution of serum.

Adenoviridae↗
PubMed1999

Analysis of the nucleoprotein gene identifies distinct lineages of viral haemorrhagic septicaemia virus within the European marine environment.

A ribonuclease (RNase) protection assay (RPA) has been used to detect nucleotide sequence variation within the nucleoprotein gene of 39 viral haemorrhagic septicaemia virus (VHSV) isolates of European marine origin. The classification of VHSV isolates based on RPA cleavage patterns permitted the identification of ten distinct groups of viruses based on differences at the molecular level. The nucleotide sequence of representatives of each of these groupings was determined and subjected to phylogenetic analysis. This revealed grouping of the European marine isolates of VHSV into three genotypes circulating within distinct geographic areas. A fourth genotype was identified comprising isolates originating from North America. Phylogenetic analyses indicated that VHSV isolates recovered from wild caught fish around the British Isles were genetically related to isolates responsible for losses in farmed turbot. Furthermore, a relationship between naturally occurring marine isolates and VHSV isolates causing mortality among rainbow trout in continental Europe was demonstrated.

Animals↗
PubMed1989

Specificity of the murine T helper cell immune response to various alphaviruses.

We investigated the specificity of the T helper (Th) cell immune response to three alphaviruses: Venezuelan equine encephalomyelitis (VEE), eastern equine encephalitis (EEE) and western equine encephalitis (WEE). Single cell suspensions were prepared from spleens of virus-primed C3H mice, and T lymphocyte populations were enriched by nylon wool chromatography. T cells were incubated in vitro with irradiated, syngeneic splenic stimulator cells previously exposed to purified virus. Cellular proliferation was measured by [3H]thymidine uptake 5 days post-stimulation. The predominant proliferating cell type secreted interleukin-2 and was of the Th cell phenotype Thy-1+, Lyt-1+,2-, L3T4+. Stimulation of VEE, EEE and WEE virus-primed Th cells with homologous and heterologous virus resulted primarily in a proliferative response specific for the immunizing virus. The corresponding antibody response, as measured by ELISA using purified virus as antigen, was also specific for the immunizing virus. The magnitude of the blastogenic response of VEE TC-83 virus-primed lymphocytes to a battery of VEE subtype viruses was remarkably similar to schemes of antigenic classification. The results indicate that the dominant Th cell epitopes on these alphaviruses represent regions largely virus-specific and lead to a virus-specific B cell response which does not change over time after primary inoculations of mice with VEE and WEE viruses and multiple inoculations of mice with EEE virus.

Alphavirus↗
PubMed1981

Antigenic relationships among Simbu serogroup (Bunyaviridae) viruses.

Antigenic relationships among 24 bunyaviruses of the Simbu serogroup were determined by complement-fixation (CF), serum dilution-plaque reduction neutralization (N) and, where possible, hemagglutination-inhibition (HI) tests. By CF, three distinct complexes of closely related viruses were identified within the serogroup. Nola and Thimiri viruses, which showed little relationship with other members of the serogroup, may represent two additional complexes. N tests in Vero cells showed that individual viruses generally were distinguishable with little difficulty. Aino and Kaikalur viruses were indistinguishable by CF or N. Seven viruses showed hemagglutination activity, and antigenic relationships among these viruses by HI paralleled those established by N tests. A classification scheme, based on both CF and N test results, for the viruses of the Simbu serogroup is proposed.

Antigens, Viral↗
PubMed2002

Composition of alphavirus-like replication complexes: involvement of virus and host encoded proteins.

The RNA-dependent RNA polymerases (RdRp's) of plus-strand RNA viruses contain one or more viral proteins. These proteins contain polymerase (POL) motifs corresponding to the active sites of the polymerase proteins. Additionally, domains corresponding to RNA helicase (HEL), methyltransferase (MT) or proteinase activity of the RdRp may be present. Comparison of available sequence data showed that each class of domain can be subdivided into two or three subclasses, and resulted in the classification of plus-strand RNA viruses into three supergroups. Here, we review our current knowledge on the composition of the RdRp's of alpha-like viruses from supergroup III. The strategy for the expression of viral replicase proteins, their stoichiometry in the enzyme complex, their mutual interactions and their possible functions in RNA synthesis are discussed. Moreover, the review covers host proteins that have been identified in viral RdRp's and their possible role in RNA synthesis.

Alphavirus↗
PubMedDate not supplied

[Monoclonal antibodies to flavivirus antigens induced by a vaccinal strain of yellow fever].

Monoclonal antibodies (MABs) YEL-2 induced by the vaccine FNS Dakar yellow fever (YF) virus were characterized for their capacity to enter into serological reactions and to react with heterologous flaviviruses. YEL-2 MABs belong to the IgG2a class of immunoglobulins, possess the antihemagglutination properties, are active in indirect IF test but do not activate complement and have no neutralizing properties. The inability to enter into CFT in the presence of antihemagglutinating properties suggests that YEL-2 MABs are directed for the structural E glycoprotein. YEL-2 MABs reacted similarly with the vaccine 17D strain and the FNS Dakar strain by which they had been induced. In addition to YF virus, YEL-2 MABs reacted with Tyuleniy, Rosio, Ilhéus, Uganda S, Karshi, and Sokuluk viruses, the reaction with Tyuleniy virus reaching the same titer as with the homologous virus but was of one-way nature. No reaction of YEL-2 MABs was observed with the viruses of the tick-borne encephalitis complex, Japanese encephalitis, West Nile, Dengue 2 and 4 viruses. These results specify the antigenic classification of flaviviruses.

Animals↗
PubMed2025

Genomics insight on passion fruit viral disease complexity.

Passion fruit viral diseases pose a significant threat to Kenya's passion fruit industry. To unravel the complexity of these diseases, comprehensive virus surveys were conducted across major passion fruit-growing counties. Passion fruit woodiness disease symptoms, like fruit hardening, chlorotic mottling, and leaf distortion, were prevalent. The study unveiled the first 23 complete genomes of Ugandan passiflora virus (UPV) and two East Asian passiflora distortion virus (EAPDV) in Kenya. UPV showed 99% nucleotide (nt) match to a UPV genome from Uganda and 66% nt identity match to EAPDV. In addition, UPV variants and two partial passion fruit green spot virus sequences and partial (passiflora emaravirus) segment RNA1-5 (novel allexivirus and an emaravirus, respectively) were detected. Phylogenetic analysis revealed distinct lineages (I-III), indicating potential multiple introductions into Kenya. Recombination analysis detected no significant breakpoints. However, the study proposed the renaming of EAPDV to passiflora distortion virus (PDV) and UPV to passiflora virus (PV) for neutral nomenclature, without geographical association. Additionally, the study highlighted the role of coinfections in symptom expression, suggesting a potential synergistic relationship between PV, PDV, and other viruses. The results recommend stringent management strategies and enhanced surveillance to mitigate the economic impact of these viruses on the Kenyan passion fruit industry. The findings from this study underscore the need to strengthen nursery certification programs and pest diagnostic protocols in Kenya. Additionally, enhanced pest surveillance and import regulations are critical to preventing the introduction and spread of emerging plant viral diseases, thereby safeguarding the country's horticultural productivity and biosecurity. To our knowledge, this is the first comprehensive study of viral diseases of passion fruit in Kenya.IMPORTANCEThis study presents the first comprehensive survey of viral pathogens affecting passion fruit in Kenya, identifying Ugandan passiflora virus (UPV) and East Asian passiflora distortion virus (EAPDV) as major contributors. Through genomic sequencing, 23 complete genomes of UPV and two of EAPDV were characterized, revealing a 99% nucleotide (nt) similarity between UPV strains from Uganda and Kenya, and 66% nt match with EAPDV. Phylogenetic analysis identified distinct lineages, suggesting possible multiple viral introductions in Kenya. The study also highlights potential synergistic coinfections between UPV, EAPDV, and other viruses, leading to more severe disease symptoms. In light of these findings, the study proposes renaming EAPDV as passiflora distortion virus and UPV as passiflora virus for a more neutral name classification. The research underscores the urgent need for enhanced surveillance, stringent phytosanitary measures, and improved management strategies to mitigate the threat of viral diseases, to safeguard the Kenyan passion fruit industry, and elsewhere.

Plant Diseases↗