A defective HIV-1 helper virus DNA, pHyPC, was assembled by deleting the RNA packaging signal, env, nef and the 3'LTR sequences. HIV-1 like virus particles that carry the HIV-1 receptor, CD4 were generated by coexpression of pHyPC and plasmid DNAs encoding different chimeric CD4 proteins. The CD4 particles, sharing the CD4 ectodomain, precisely fused to different membrane anchors. CD4(+) particles specifically bound to HIV-1 Env expressing cells, but any signs of infection into these cells were not detected. Binding was only partially blocked by either polyclonal anti-CD4 antibodies or by high concentrations of soluble CD4. Suprisingly, CD4(+) particles also adsorbed to HeLa, CHO, NIH3T3 and COS-7 cells in the absence of HIV-1 Env expression. Adsorption was comparable in strength and speed to the highly specific CD4-Env interaction. CD4(-) particles exhibited only background levels of binding. Cell binding was CD4- dependent, but it was independent of the cell type from which the CD4(+) particles originated. Interestingly, CD4-dependent/Env-independent binding was only found when CD4 was present on virus particles. This suggests that the micro-environment of CD4 on virus particles uniquely expose this new cell binding activity. Its high affinity could explain in part why infection of Env(+) cells by CD4(+) particles was not detected. Further experiments will be required to evlauate whether this strong membrane interaction could represent one step in the multiple-step viral entry process.
Adsorption ; Animals ; Antibodies ; COS Cells ; DNA ; Helper Viruses ; HIV-1* ; Membranes ; Plasmids ; Product Packaging ; RNA ; Virion

We have determined and analyzed the full-length cDNA sequence of a coxsackievirus B3 (CVB3) Korean isolate (CVB3-Korea/97) which has been known as a general human pathogen. The whole genome contains 7,400 nucleotides and has a single large open reading frame with 6,555 nucleotides that encodes a potential polyprotein precursor of 2,185 amino acids. The genome also contains a 5' non-coding region (NCR) of 741 bases and a 3' NCR of 104 bases followed by poly(A) tail. Sequence homologies of nucleotides and deduced amino acids between the CVB3-Korea/97 strain and the prototype (Nancy strain) were 81.7% and 91.5%, respectively. The genes encoding the functional proteins including viral protease and RNA dependent RNA polymerase showed higher homology than those encoding the structural proteins. We have further analyzed the sequences of 5' NCR, VP1 and VP2 of CVB3-Korea/97, which are known as cardiovirulent determining factors at the nucleotide and amino acid levels. Although the CVB 3-Korea/97 strain was isolated from an aseptic meningitis patient without cardiomyopathy, its 234th nucleotide and 165th amino acid were uracil and Asn as same as those of other cardiovirulent strains one. However, the 155th amino acid of VR1, which closely associated with cardiovirulence, was replaced with Arg155 by single nucleoptide substitution from A2916 to T2916. Moreover, additional amino acid substitutions were observed in the flanking region of Asp155. Taken together, aminoacid(s) substitution in VP1 may play a critical role in determining cardiovirulence of the CVB3-Korea/97 strain rather than individual nucleotide replacements in the 5' NCR and/or an amino acid substitution in VP2.
Amino Acid Substitution ; Amino Acids ; Cardiomyopathies ; Clone Cells* ; Cloning, Organism* ; DNA, Complementary* ; Genome ; Humans ; Korea* ; Meningitis, Aseptic ; Nucleotides ; Open Reading Frames ; RNA Replicase ; RNA, Messenger ; Sequence Analysis* ; Sequence Homology ; Uracil

Standard plaque assay using agarose-overlay has long been used for titration of many infectious virus particle. Plaque assay for the titration of varicella-zoster virus and its live vaccine requires three intermittent agarose overlay to visualize plaques. Overall procedure of the assay takes at least nine days from virus inoculation and microbe contamination including fungi is frequently accompanied during incubation period. We studied whether an immunofocus assay in conjunction with peroxidase-mediated immunohistochemical reaction may replace the standard plaque assay for the virus titration by comparing the two methods. A linear relationship was observed between number of foci and virus dilution. The number of foci in a given dilution of virus appeared a little higher than counted plaques formed in standard plaque assay. Independent titration results obtained from two assay methods for a given dilution of virus demonstrated a strong correlation (r2=0.99). Foci of virus infected cells as revealed by the enzyme reaction could be counted either 4 days post-infection (p.i.) under low magnification (40X) microscopy, or 6 days p.i. by naked eye observation. Larger size of cell cuture plate, virus adsorption at 35 degrees C, and 10% FBS in diluent appeared to be better conditions for the assay. Immunofocus assay will be an effective and dependable titration method for varicella-zoster virus and its live vaccine in place of the standard plaque assay in respect to accuracy, costs, and experimental convenience.
Adsorption ; Fungi ; Herpesvirus 3, Human* ; Microscopy ; Sepharose ; Virion

No Abstract Available.
Hepacivirus* ; Hepatitis C* ; Hepatitis*

No Abstract Available.

No Abstract Available.
Genes, pol* ; Korea* ; Leukemia Virus, Bovine* ; Proviruses*

No Abstract Available.
Cytomegalovirus* ; Enzyme-Linked Immunosorbent Assay* ; Humans*

No Abstract Available.
Korea* ; Mumps virus* ; Mumps*

No Abstract Available.
Humans ; Infant* ; Korea* ; Rotavirus* ; Sequence Analysis*

No Abstract Available.
HIV-1* ; Transcription Factors*