Nonencapsidated infectious DNA of adeno-satellite virus in cells coinfected with herpesvirus.

Adeno-associated satellite viruses produce antigen detectable by immunofluorescence but not infectious virus in tissue culture cells coinfected with herpes simplex virus. Analysis of DNA extracts from these infected cells shows that large amounts of infectious satellite virus DNA are produced but not encapsidated in the system. This result indicates that satellite virus may be defective at the maturation step.

Molecular weight of base plates of bacteriophage T4D.

Highly purified base plates of bacteriophage T4D were obtained from lysate of gene 19 am mutant of this phage by differential centrifugation and sucrose gradient. Base plates were studied by means of high speed sedimentation equilibrium. The molecular weight determined by this method is (6.7 plus or minus 0.2)-10-6.

Subunit arrangement in the extended sheath of pyocin R.

An optical diffraction study has been made of electron micrographs of extended sheaths of pyocin R. It has been demonstrated that the extended sheath consists of annuli of six subunits, which are arranged in a helix of 3.57 annuli per one turn. The annulus repeat in the helix direction is 35A. The dimensions and probably the helical parameters of pyocin R sheath are different from those of T4 phage tail, but a structural correlation appears to exist between the extended sheath of pyocin R and that of the phage tail.

Hepatitis B-DNA replication and histological patterns in liver biopsy specimens of chronic HBsAg positive patients with and without hepatitis delta virus superinfection.

The role of active hepatitis B virus (HBV) infection in chronic HBsAg positive hepatitis with and without hepatitis delta virus (HDV) superinfection was analysed in percutaneous liver biopsy specimens from 50 patients. Each specimen was divided into two--one part for histological evaluation and for the detection of HBcAg and delta antigen; the other part was tested for HBV-DNA using Southern blotting. Ten cases were of chronic lobular hepatitis, 10 of chronic persistent hepatitis, and 30 of chronic active hepatitis. Ten cases were delta antigen positive and showed high grade lobular activity but no evidence of HBV-DNA episomal forms or HBcAg reactivity. Twenty one cases showed HBV-DNA replicative intermediate forms; 19 had high grade lobular activity, which occurred in five cases without evidence of free viral DNA. Of the 21 biopsy specimens with HBV-DNA episomal forms, 14 were positive for HBcAg; only one of the 19 cases without detectable viral DNA was positive for such antigen. These data indicate that the presence of HBV or HDV active infection correlates with the histological finding of prominent lobular necrosis. Moreover, intrahepatic HBV-DNA seems to be a more sensitive marker than the presence of viral antigens for indicating HBV replication.

Ultrastructural, protein composition, and antigenic comparison of psittacine beak and feather disease virus purified from four genera of psittacine birds.

Psittacine beak and feather disease (PBFD) virus, was purified from diseased tissues of a lesser sulphur-crested cockatoo (Cacatua sulphurea), a black palm cockatoo (Probosiger aterrimus), a red-lored Amazon parrot (Amazona autumnalis), and a peach-faced lovebird (Agapornis roseicollis). The histopathology of diseased feathers and follicular epithelium from the different species was compared; basophilic intranuclear inclusion bodies were identified in the follicular epithelium and intracytoplasmic globular inclusions were observed within macrophages located in the feather pulp from the four species. Psittacine beak and feather disease virus antigen was specifically detected by colloidal gold immunoelectron microscopy. The different preparations of purified virions displayed an icosahedral symmetry, were non-enveloped, and had a mean diameter that varied from 12 to 15 nm when negatively stained. Two major viral-associated proteins with approximate molecular weights of 26 and 23 kilodaltons (kd) were consistently demonstrated from the four viral preparations. Purified virions from the four genera were antigenically related. These findings suggest that the PBFD virus purified from numerous genera of diseased birds is similar based on ultrastructural characteristics, protein composition and antigenic reactivity.

[Nature of the easily melted portions of DNA with a quasi-random base sequence]. / O prirode legkoplavkikh uchastkov DNK s kvazisluchainoi posledovatel'nost'iu osnovanii.

The influence of denaturation conditions upon the character of partial denaturation of DNA with random base distribution were thoroughly studied. Maps of partial DNA denaturation were obtained at T less than TAT for phage phiB DNA at pH 10.7 and 5.5; Tg9 DNA at pH 8.8; at T less than TAT for phiB DNA at pH 10.9 and Tg9 DNA at pH 8.8. The map quality was better when obtained at higher pH values; the peaks became sharper and higher against the background. We failed to obtain maps of partial denaturation at pH 5.5, T less than TAT. The improvement of the map quality and existence of the partial denaturation maps at T less than TAT at pH 10.9 were explained by the increase of primary melting probability of AT-rich DNA regions. At high pH the denaturation map quality was temperature independent. This was explained by a very weak temperature dependence of primary melting probability for all maps of equal quality. The map quality became worse, when the quantity of loops was increased.

[Biological and physicochemical properties of virus PBV-1, isolated from Penicillium brevi compactum]. / Nekotorye biologicheskie i fiziko-khimicheskie svoistva virusa PBV-1, vydelennogo iz Penicillium brevi compactum

High infectivity of PBV-1 virus for different strains of E. coli has been demonstrated. Sizes of the virus particle are; head diameter 513 angstrom, length of the process 1500 angstrom, diameter of the process 60 angstrom. The buoyant density of the virus in cesium chloride density gradient is 1.49 g/cm3, in cesium sulphate-1.39 g/cm3, the sedimentation constant of the virus particle is 380S; molecular weight is 52.8 plus or minus 1.9 times 10-6 daltons. The PBV-1 virus contains double-stranded DNA with the melting temperature in 1 SSC (0.15 M NaCl plus 0.0015 M sodium citrate, pH 7.0) and in 0.1 SSC-88.5 degrees C, respectively. The buoyant density of DNA in cesium chloride gradient is 1.7058 g/cm3 and in cesium sulphate 1.424 g/cm3. The content of GC-pairs calculated by the melting temperature is 46.5% and by the buoyant density 46.7%. On the basis of DNA sedimentation constant value (30S) the average molecular weight of DNA has been calculated to be 23.7 times 10-6 daltons.