Electron microscopical study of initial and final stages of fowl plague virus-replication in chick embryo cells

Total viral genome copies and virus-Ig complexes after infection with influenza virus in the nasal secretions of immunized mice

The kinetics of infectious virus (p.f.u.), total virus and virus-Ig complex formation following influenza A/PR8 (H1N1) viral infection was examined in the nasal secretions of naive mice and mice immunized with A/PR8, A/Yamagata (H1N1), A/Guizhou (H3N2) and B/Ibaraki influenza viruses. The total number of virus particles and the number within virus-Ig complexes, captured in advance using an anti-mouse Ig-coated plate, were determined on the basis of viral genome copy number using quantitative RT-PCR. The kinetics of infectious and total virus particle formation, the latter of which increased by 10(3)-10(4)-fold above infectious virus numbers, showed that virus elimination from the nasal area was earlier in A/PR8, A/Yamagata and A/Guizhou-X virus-immunized mice, in decreasing order, compared with naive mice. Early virus elimination correlated with the level of A/PR8 virus-reactive antibodies in immunized mice. Virus elimination coincided with the appearance of virus-Ig complexes shortly after infection. This result suggested that antibodies led to the formation of immune complexes in a dose-dependent manner together with a reduction in number of infectious virus particles. The fact that a large number of virus particles was observed in immune complexes for a wide range antibody levels made it difficult to detect slight differences in virus number within the immune complexes, depending on antibody level. These results suggested that the formation of virus-Ig complexes in virus-immunized mice shortly after infection is involved in early virus elimination, which is determined by the strength of protective immunity against challenge viruses.

Ruthenium red preserves glycoprotein peplomers of C-type retroviruses for transmission electron microscopy

Peplomers, the glycoprotein projections of the outer viral envelope, are distinctive for many viruses. Peplomers of retroviral C-type particles are fragile and are not preserved in standard preparations for transmission electron microscopy of thin sections, whereas the peplomers of B- and D- type retroviruses are usually preserved. Ruthenium red, extensively used in transmission electron microscopy to enhance the preservation of glycosylated proteins, was used in the preparation of three retrovirus-producing lymphoblastoid cell lines: murine SC-1 cells producing the C-type murine leukemia retrovirus LP-BM5 that causes immunodeficiency, human DG-75 cells producing a murine leukemia retrovirus, and human C5/MJ cells producing human T-cell lymphotropic virus type I (HTLV-I). Fixation of cells was carried out with ruthenium red present in the glutaraldehyde, osmium tetroxide, and the ethanol dehydration through the 70% ethanol step. The detailed structure of peplomers of these three different viruses was well preserved.

[Electronoptical studies of the effect of 1-[p-(methylnitrosamino)-benzylidenamino]-adamantane on the fowl plague virus (FPV) in cell culture]

The adamantanamine derivative 1-[p-(methylnitrosamino)-benzylidenamino]-adamantane (MBAA) at a concentration of 40 microgram/ml demonstrated no effect on adsorption of fowl plague virus (FPV) on chick embryonal cells. The penetration of the virions took place by means of pinocytosis. In the final stages of penetration the virions became gradually disintegrated. Under the influence of MBAA, after break-down of the membrane of pinocytic vesicles a swollen part of the virus core remained in cytoplasm. The morphologically visible replication stages were completely blocked by MBAA. From these results it was concluded that the antiviral action of MBAA most probably depends on a block of virus replication between the final stages of the penetration process and the beginning of production of virus specific structural antigens.