Gradocol Membranes Research Articles

A NEW VIRUS DISEASE OF THE TOMATO

Summary.A new virus disease of the tomato plant is described. An account is given of the symptoms produced on a variety of host plants, mostly in the Solanaceae. Some of the physical properties of the virus have been investigated and its particle size measured by ultrafiltration through Gradocol membranes. The size as measured by filtration in plant sap is approximately 17–25 mμ. The virus is compared with other viruses commonly affecting tomato and tobacco and methods of differentiating them are discussed.

The Preparation of Gradocol Membranes and their Application in the Study of Plant Viruses

An account is given of the preparation of Elford's gradocol membranes and their application in the study of plant viruses. The technique is discussed step by step and the chief sources of error are indicated. It is shown that plant virus suspensions clog the membranes, and suggestions are made for the preparation of those suspensions for filtration. The effect of virus content, purification and pH of virus fluids upon their filtration is discussed.

A Virus from Influenza Patients

The causation of epidemic influenza has proved a perplexing problem for the bacteriologist. Of the bacterial organisms associated with the disease, Pfeiffers influenza bacillus, the most frequent, and others do not appear to be capable of reproducing the cardinal features of the disease, but only some of the secondary symptoms. Another difficulty encountered is the insusceptibility of most animals to human influenza, the so-called influenzas of animals being distinct from the human. Latterly, attempts have been made to detect a virus in the disease, hitherto with little or no success, but in a recent communication, Smith, Andrewes and Laidlaw describe results obtained with ferrets (Lancet, July 8, p. 66). A febrile disease is produced in ferrets by the intranasal instillation of filtrates of throat washings obtained from influenza patients, which is transmissible serially in ferrets either by contact or by intranasal instillation of virus material from infected ferrets. Filtration was conducted through Gradocol membranes so that the filtrate is bacteria free. Throat-washings from healthy persons and influenza convalescents caused no illness in ferrets. The disease in ferrets has some likeness to human influenza, with nasal and pulmonary catarrh and occasionally a relapse. The blood-serum of a ferret that has recovered, and also that of recovered human cases, neutralises the virus. The virus of swine influenza, described by Shope, has a close antigenic relationship with the influenza virus, and induces a disease in ferrets very like that produced with the influenza virus. A prima facie case has indirectly been made out for an attempt to transfer the ferret disease back again to man, and a technique has been discovered which can be exploited fruitfully when the next human epidemic occurs.