phi gamma: A coliphage coliphage related to, but distinct from the phi 80 virion

The coliphage phi gamma, though capable of genetic recombination with phi 80, is morphologically distinct from the phi 80 virion. It has a prolate head (58.4 X 46.7 nm) bearing a tail (143 nm) which is strikingly flexible. On the basis of their buoyant density in CsC1, both infectious and transducing phi gamma particles form a single population. This density value is slightly higher than that of the phi 80 virion. The phi gamma chromosome is a double-stranded linear DNA molecule of 13.4 mum in length (corresponding mol. wt.: 27.6 X 10(6)). From its melting temperature and its buoyant density in CsC1, phi gamma DNA appears to have a base composition very close to that of Escherichia coli DNA.

[Differential ultrastructural elements in human cytomegalovirus and Herpes simplex virus replication in cultures of human cells]

Differential ultrastructural features in the replicative cycle between a strain of human cytomegalovirus (CMV) and two strains (types 1 and 2) of herpes simplex virus (HSV) have been studied by electron microscopy. Either on the same or different host cell system four differential aspects have been constantly observed: a) presence in CMV infected cells of a large nuclear inclusion, lacking in HSV infected cells; b) envelopment of CMV capsids by microvescicular systems near the nuclear membrane, whereas HSV (types 1 and 2) takes envelope from the inner lamina of the nuclear membrane; c) presence in the cytoplasm of CMV infected cells of homogeneous dense material and dense microbodies, lacking in HSV infected cells; d) in extracellular space homogenous dense microbodies are present only in CMV infected cell cultures. Diagnostic usefulness of the above reported ultrastructural differences and their meaning on the basis of most recent data of the literature are discussed, with special concern to envelopment of two viruses and to the nature of homogeneous dense material observed in CMV infected cells.

Cytomegalovirus: nucleocapsid assembly and core structure

New ultrastructual aspects of cytomegalovirus nucleocapsid assembly are illustrated in cells from a Kaposi sarcoma. The occurrence of viral deoxyribonucleoproteins in the form of strands and penetration of these strands into open capsids is illustrated. The geometrical arrangement of the core material of the nucleocapsid is aslo emphasized.

Morphological components of herpesvirus. I. Intercapsomeric fibrils and the geometry of the capsid

Highly purified equine herpesvirus type 1 (EHV-1) and herpes simplex virus type 1 (HSV-1) were observed by electron microscopy in various stages of disintegration. Under the conditions used, envelopes of virions usually were fragmented, and virus capsids collapsed in situ into flattened sheets of capsomeres. A matrix of intercapsomeric fibrils was observed. Evidence suggesting that the capsid hexamer has threefold structural symmetry is presented.

Bacteriophage: An Unusual Hybrid of Serologically Unrelated Phages P22 and P221

Serologically unrelated bacteriophages P22 and P221 that grow on Salmonella typhimurium are described. The phage P22 and a mutant P22h have short tails with hexagonal base plates, whereas P221 has a long, flexible tail without a base plate. P22h and P221 can recombine to exchange genetic markers. In the course of the recombination experiment, an unusual hybrid, P22-221Hy, was found. It mutates to P221 and P22S at a frequency of 10(-4) and 1O(-5), respectively. Unlike P22h, P22S gives clear plaques on both S. typhimurium, St, and its mutant, St/22, but is morphologically and serologically indistinguishable from P22 and P22h. The use of single-clone technique on P22-221Hy proved that a P22-221Hy genome consists of a P22h and a P221 genome and is carried by the P22h capsid. However, it seems probable that the information for synthesizing the P221 capsid may be suppressed by the information for synthesizing the P22h capsid. P22-221Hy is a stable hybrid rather than a heterozygote, because it does not segregate by passing through host cells. Thus,, one bacteriophage can carry the genetic information for two distinct bacteriophages.

Icosahedral Models and Viruses: A Critical Evaluation

The evidence for a 42 capsomere structure for the capsid of the papova viruses and 92 for reovirus and woundtumor viruses is corroborated. Some of the difficulties inherent in comparing large-scale icosahedral models with high-resolution electron micrographs of virus particles displaying cubic symmetry are discussed.

On the identity of the cotton capsid of Uganda

For some years prior to 1935, the cotton Capsid of Uganda, which is now known to occur in several other parts of Africa also, was called Lygus vosseleri, Popp. In 1935, Mr. W. E. China of the British Museum (Natural History), after examining type material, published a note synonymising vosseleri of Poppius with simonyi of Reuter and concluded that the cotton Capsid previously identified by him as L. vosseleri, Popp., must therefore be called L. simonyi, Reut. This latter name has been in general use for the cotton Capsid since 1935 and is very widely known because of the great importance of the insect as a pest of cotton.