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At least 235 records · Page 13Linked to original sources
PubMed1986

Geographic classification of dengue-2 virus strains by antigen signature analysis.

Dengue-2 virus strains from different locations were compared by T1-RNAse-resistant oligonucleotide fingerprinting and antigen signature analysis. The latter technique involved construction of radioimmunoassays using monoclonal antibodies that recognize nine distinct dengue-2 type-specific and flavivirus cross-reactive epitopes over a range of antigen concentrations. A statistical method was used to align unknown dengue antigen concentrations in different strain preparations, allowing comparison of binding profiles. Twenty-six dengue-2 virus strains were separated into five distinct groups (topotypes) on the basis of unique RNA fingerprints. Two of these were represented by New Guinea C, the prototype virus isolated in 1944, and a Philippine strain; others were segregated on the basis of greater than or equal to 80% shared oligonucleotides into similarity groups representing Burma/Thailand (8 strains), Puerto Rico (12 strains), and Jamaica (4 strains). Signature analysis of the prototype and four geographic topotype strains revealed striking antigenic differences. In contrast, a high degree of antigenic similarity was found among strains from the same geographic region. Variation between antigenically distinct strains occurred at both type-specific and group-reactive epitopes, but the widest differences appeared at group-reactive determinants. Signature analysis provides a more rapid and simpler means than RNA fingerprinting of monitoring changes or new introductions of dengue virus populations in a geographic region.

Antibodies, Monoclonal↗
PubMed1992

Functional classification of simian immunodeficiency virus isolated from a chimpanzee by transactivators.

In reporter-based transient expression systems, we characterized simian immunodeficiency virus from a chimpanzee (SIVCPZ), with special reference to the human immunodeficiency virus type 1 (HIV-1). SIVCPZ was not equally activated by tat and rev transactivators derived from representative primate lentiviruses. HIV-1 alone activated SIVCPZ to the full extent in both tat and rev assays. The tat and rev gene products of SIVCPZ, as well as those of HIV-1, efficiently transactivated the other viruses. These results indicate that SIVCPZ is identical to HIV-1 with regard to the compatibility of tat and rev gene activities among four subgroups of primate lentiviruses.

Amino Acid Sequence↗
PubMed1995

Classification of hepatitis C virus into major types and subtypes based on molecular evolutionary analysis.

Molecular evolutionary analysis was applied to determine the number of hepatitis C virus (HCV) types and subtypes based on all the HCV nucleotide sequences available from the DNA data banks (DDBJ, GenBank (NCBI), EMBL) and the literature. There was an excellent concordance among the types and subtypes assigned based on different HCV genomic regions. Only one HCV isolate was assigned to different HCV types based on the 5' non-coding (NC) and envelope 1 (E1) regions. The 5' NC region was well conserved and could be used to assign only types and not subtypes. From the sequence data available there were 13 subtypes based on the core region and 14 subtypes based on the E1 and non-structural protein 5 (NS5) regions.

Biological Evolution↗
PubMed1992

Properties and classification of hepatitis A virus.

Hepatitis A virus (HAV) is a member of the picornavirus family. It was first provisionally classified as enterovirus 72, but subsequent determinations of its nucleotide and amino acid sequences showed them to be sufficiently distinct to assign the virus to a new genus. Heparna-virus (Hep-A-RNA-virus) has been suggested as the genus name. HAV shares the key properties of the picornavirus family: an icosahedral particle 28 nm in diameter with cubic symmetry, composed of 30% RNA and 70% protein. The genome is single-stranded 7.48 kb RNA, linear and positive-sense. Like other picornaviruses, HAV possesses four major polypeptides cleaved from a large precursor polyprotein. The surface proteins VP1 and VP3 are major antibody-binding sites. The internal protein VP4 is much smaller than the VP4s of other picornaviruses. As other picornaviruses, HAV has no envelope and replicates in the cytoplasm. HAV is stable to treatment with either and acid, and is much more heat-resistant than other picornaviruses. It withstands 60 degrees C for 1 h. MgCl2 stabilizes the virus to withstand temperatures up to 80 degrees C. The relative resistance of HAV to disinfection indicates a need for extra precautions in dealing with hepatitis patients and their products. Only one serotype is known. There is no antigenic cross-reactivity with other hepatitis viruses. HAV initially was identified in stool and liver preparations by employing immune electron microscopy as the detection system. Chimpanzees and marmoset monkeys are susceptible to HAV. HAV has been cultivated serially in primary explant cultures of adult marmoset livers and in cell lines of primate origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Classification of hepatitis B virus genotypes by the PCR-Invader method with genotype-specific probes.

Hepatitis B virus is a worldwide public health problem. A simple and effective test to identify viral genotypes would greatly aid efforts to understand and control the spread of this disease. A serial invasive signal amplification reaction assay (PCR-Invader assay) was developed for distinguishing the known eight genotypes (A-H) and four subgenotypes (Aa, Ae, Ba, Bj) of hepatitis B virus (HBV). The preS/S and core regions were amplified by multiplex PCR and delivered to 12 wells containing genotype-specific Invader probes. By observing the fluorescence patterns in the wells, HBV sub/genotypes can be assigned. A total of 505 serum samples containing HBV/HBsAg in Japan was examined by PCR-Invader and compared the results with those from ELISA assays with monoclonal antibodies against epitopes on gene products of the preS2 region and with a genotype-specific probe assay (GSPA) based on the preS1 region. Genotypes determined by the PCR-Invader agreed with those of the ELISA method in 98.2% of cases and with the GSPA method in 97.1% of cases. Co-infection with two distinct genotypes was correctly identified by the PCR-Invader in four serum samples, as determined by GSPA. Thus, the PCR-Invader assay is a useful tool for detecting the 10 known HBV sub/genotypes.

Base Sequence↗
PubMed1986

Classification of Barmah Forest virus as an alphavirus using cytotoxic T cell assays.

Barmah Forest virus, an arbovirus, does not cross-react convincingly with alpha-, flavi- or bunyavirus immune sera. Secondary cytotoxic T cells generated in vitro immune to a number of alphaviruses cross-lyse Barmah Forest virus-infected target cells. Flavivirus (West Nile and Kunjin)- and Bunyamwera virus-immune Tc cells lyse homologous virus-infected target cells, but not alphavirus-infected targets. Using cytotoxic T cell assays Barmah Forest virus can be classified as an alphavirus.

Alphavirus↗
PubMed1999

Evolutionary pattern of the G glycoprotein of human respiratory syncytial viruses from antigenic group B: the use of alternative termination codons and lineage diversification.

Partial sequences of the G protein gene of 33 isolates from antigenic group B of human respiratory syncytial virus were determined. Phylogenetic analysis indicated that the evolutionary pattern of group B viruses is similar to that previously described for isolates of antigenic group A, including worldwide distribution of related viruses and co-circulation of viruses from different lineages during the same epidemic. Dominance of AG+GA over UC+CU transitions was observed when G sequences of group B viruses were compared, as previously found in viruses from antigenic group A. Interestingly, differences in protein length, determined by the usage of alternative termination codons, were more pronounced in group B than in group A viruses. Changes in protein length correlated with the classification of viruses in different lineages. Thus, mutations that determined termination codon usage seem to have played an important role in the diversification of group B viruses.

Alternative Splicing↗