[Processing of vaccinia genome terminal: initiation of DNA synthesis and concatemer resolution].
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Biomedical subjects
Publications and source records attributed to M Oie.
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Although some other organizations encourage staff input into employee selection, the advanced care department at Bellin Hospital in Green Bay, Wisconsin has taken this concept to a new level by implementing an autonomous interview team. This team is empowered to make hiring decisions for all positions within the department without management influence or interference.
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The vaccinia virus hemagglutinin (HA) has specific affinity for the structural protein, VP37K. The nature of this affinity and its relationship to the function of the HA were analyzed using HA mutants. The VP37K reactive site of the HA molecule is located in its transmembrane region, and the vaccinia virus HA associates with the viral particle via the VP37K-HA affinity. The viruses possessing an HA with fusion inhibitor activity were largely of the low infectivity form, whereas the viruses that associated mutant HAs defective in the activity were of the high infectivity form. D1 mutant virus does not produce HA. When it was incubated with the HA of the IHD-J strain, the HA associated with the virus particle. The HA-loaded D1 mutant virus acquired a high affinity not only for chick erythrocytes but also for KB and Vero cells. At the same time, the infectivity for Vero cells was decreased. The original high infectivity was recovered by treatment with trypsin. The virion-associated vaccinia HA has two functions; the HA protects the infectivity of the virus by the fusion inhibitor activity and exhibits affinity against host cells. Vaccinia virus first adsorbs to the cell via HA, and then proteolysis of the HA activates the second adsorption site which seems to be the fusogenic site of the virus. Proteolytic activation represents removal of the fusion inhibitor activity of the HA.
Vaccinia virus IHD-J strain induces hemagglutinin (HA) on the surface membrane of infected cells and does not elicit cell-cell fusion (F-). We isolated 21 independent hemadsorption-negative (HAD-) mutant viruses from IHD-J and five HAD+ revertants from one of these mutants. Of the 21 mutants, 19 that synthesized either no or little HA at the cell surface caused cell-cell fusion (F+), whereas none of the five revertants that synthesized HA at the cell surface induced cell-cell fusion. Furthermore, anti-HA monoclonal antibody B2D10 induced extensive polykaryocytosis of IHD-J-infected cells and suppressed the ability of the IHD-J-infected cell extract to inhibit the polykaryocytosis induced by IHD-W. The other 2 of the 21 HAD- mutants, B1 and A2, which induced HAs at the cell surface, showed F- and F+ phenotype, respectively. The HA molecule of mutant B1 had a single amino acid substitution of Lys for Glu-121 in its extracellular domain, whereas that of mutant A2 had a single substitution mutation of Tyr for Cys-103. We conclude that the vaccinia HA is a fusion inhibition protein, that the active sites for the two activities reside separately in its extracellular domain, and that cysteine-103 is important in forming the proper tertiary structure of the protein to exert both activities.
Epitopes on the surface components of orthopoxviruses were analyzed with monoclonal antibodies (MAbs) against monkeypox and vaccinia viruses by enzyme-linked immunosorbent assay (ELISA), Western blotting (WB), radioimmunoprecipitation (RIP), and competitive binding inhibition assay (CBIA). When compared by ELISA, three vaccinia virus strains exhibited a similar reactivity to 99 tested MAbs despite their remote passage history. All five isolates of monkeypox virus closely resembled one another, irrespective of the host species (human, monkey, squirrel) from which they were isolated. Taterapox virus reacted similar to vaccinia virus against 97 of the 99 tested MAbs, and reacted with 2 MAbs which were cross-reactive with monkeypox and mousepox. Mousepox and cowpox viruses reacted with these MAbs in a species-specific manner: MAbs reactive to cowpox virus distinctly differ from those reactive to mousepox virus. Of the 99 tested MAbs, 32 reacted with all the 11 tested orthopoxviruses, indicating that the corresponding epitopes existed in all the viruses. Fifty-four MAbs reacted with two or more virus species and were classified as partially common MAbs. Eight MAbs were apparently type-specific for monkeypox, and five were specific for vaccinia and taterapox viruses. No strain-specific epitope was detected. Sera of monkeypox-infected patients, when analyzed by CBIA, interfered with the binding of monkeypox-specific MAb H12C1 but not of vaccinia-specific MAb G6C6. Sera of monkeypox-infected patients who had been vaccinated competed against both MAbs, demonstrating the original antigenic sin phenomenon. The two MAbs could distinguish between the sera of monkeypox patients and those of vaccinated persons. However, the serum of a smallpox patient was competitive against these apparently vaccinia- or monkeypox-specific MAbs. Three of the eight monkeypox-specific epitopes were recognized by the above CBIA test, which suggests that they also exist in smallpox virus. The mosaic-like combination of common epitopes and the small number of type-specific epitopes manifested the antigenic characteristics of orthopox viruses. The species boundary was obscured due to the partially common epitopes, but the total composition of epitopes was stable enough to maintain the antigenic species-specificity. The mutual relationship of the orthopoxviruses was visualized in a three-dimensional network.
Modifications induced in structural vaccinia virus proteins that elicit the high infectious state by virus activating treatments involving trypsin and phosphatidylserine were analyzed using antivaccinia monoclonal antibodies (MABs). MABs reactive against each of the five outer layer proteins (VP54K, 34K, 32K, 29K, and 17K-25K) neutralized infectivity. VP54K possesses at least two neutralizing epitopes. Treatment with trypsin or with isolated plasma membrane cleaved VP54K into TVP41K carrying epitope A and removed a fragment containing epitope B from the virus. MABs against either of the epitopes could neutralize the virus. The exposure of epitope A concomitantly activated virus infectivity, and it was an essential step of penetration. MABs against VP17K-25K reacted more efficiently with trypsin-treated virus than with untreated virus, but the size of VP17K-25K was not affected by trypsin; this finding indicated that trypsin treatment rendered the VP17K-25K epitopes more accessible to antibody and hence to neutralization. MABs against VP32K and VP29K neutralized infectivity to the same extent irrespective of the state of activation. Virus treated with phosphatidylserine (PS) was neutralized more efficiently by MAB against VP34K than untreated virus, but the amount of antibody that reacted with the virus was the same before and after treatment with PS. Phosphatidylserine did not modify epitope structure itself, but it activated the function of VP34K. It was concluded that blocking of the functions attributed to any of the five proteins resulted in neutralization of virus infectivity, and treatment with trypsin and phosphatidylserine activates infectivity of vaccinia virus by modifying three of them (VP54K, VP34K, VP17K-25K) with characteristic behavior for each protein.