The titration of vaccinial neutralizing antibody on chorio-allantoic membranes

A study has been made of various factors involved in performing neutralization tests with vaccinia virus on chorio-allantoic membranes.

The common practice of using a single serum concentration has been shown to result in a test which is qualitative only. The linear relationship between the logarithm of the pock count of the surviving virus and the logarithm of the serum dilution can be used to determine the dilution of serum which will neutralize 50% of a virus suspension. By this method it is possible to distinguish between sera whose potencies vary by about fourfold.

I gratefully acknowledge the advice and criticism given by Dr J. C. N. Westwood and Dr I. A. Macpherson, as well as the help given by Mr S. Peto with the statistical treatment of results. My thanks are also due to Mr H. B. Maber and Corporal M. Fitzpatrick, R.A.M.C., for their technical assistance.

HYBRIDS DERIVED FROM THE VIRUSES OF VARIOLA MAJOR AND COWPOX

The characterization of 16 clones of virus derived from mixed infections with variola major and cowpox has been described. This work has involved the description of the plaques produced by variola major in chick embryo monolayers, and a more detailed study of the effects of raised temperature on pock production by pox viruses on the C.A.M.

Two of the variola major—cowpox clones were found to correspond to cowpox virus, while the other 14 shared various combinations of parental characters. Among them there were 10 distinct new types of virus. Evidence of the stability of these viruses has been presented.

Analysis of the combination of characters encountered among the hybrids has given good evidence that all the eight marker characters used segregate independently. A particular instance of this was the character of chick embryo virulence which, among the hybrid viruses, was shown to be unrelated either to ceiling temperature or speed of plaque formation.

The significance of these findings in relation to the general problem of virulence has been briefly discussed. The possibility that vaccinia may have originated as a hybrid of variola and cowpox has lso been considered.

Arabinofuranosyl Thymine Derivatives-Potential Candidates against Cowpox Virus: A Computational Screening Study

Cowpox is caused by a DNA virus known as the cowpox virus (CPXV) belonging to the Orthopoxvirus genus in the family Poxviridae. Cowpox is a zoonotic disease with the broadest host range among the known poxviruses. The natural reservoir hosts of CPXV are wild rodents. Recently, the cases of orthopoxviral infections have been increasing worldwide, and cowpox is considered the most common orthopoxviral infection in Europe. Cowpox is often a self-limiting disease, although cidofovir or anti-vaccinia gammaglobulin can be used in severe and disseminated cases of human cowpox. In this computational study, a molecular docking analysis of thymine- and arabinofuranosyl-thymine-related structures (1-21) on two cowpox-encoded proteins was performed with respect to the cidofovir standard and a 3D ligand-based pharmacophore model was generated. Three chemical structures (PubChem IDs: 123370001, 154137224, and 90413364) were identified as potential candidates for anti-cowpox agents. Further studies combining in vitro and in silico molecular dynamics simulations to test the stability of these promising compounds could effectively improve the future design of cowpox virus inhibitors, as molecular docking studies are not sufficient to consider a ligand a potential drug.

Smallpox--a retrospect

Smallpox has been known as a disease of man since the earliest times. However, its severity increased greatly during the eighteenth century, stimulating physicians and others to find methods of protection against it. Variolation (the inoculation of smallpox material into the skin) was tried, and for a while found general approval, although its practice was not without danger. In 1796, Edward Jenner began his investigations into the use of cow-pox material (vaccination) as a prophylactic against smallpox, and later showed that vaccination could confer protection. Although vaccination centres were first set up in Canada early in the nineteenth century, the disease on occasion assumed epidemic proportions, such as occurred in Montreal in 1885. Sporadic outbreaks have occurred since then, including the recent case in Toronto. From the public health point of view, maintenance of a high level of immunity to smallpox throughout the general population is necessary if serious epidemics are to be avoided.

[Two hundred years ago: the first smallpox vaccinations in Vienna]

The first successful smallpox vaccination with cowpox lymph outside of England was carried out in Vienna--only ten months after the publication of Edward Jenner's book "An Inquiry into the Causes and Effects of the Variolae Vaccinae, a Disease ... known by the Name of the Cow Pox", and only a little more than three months after the first vaccinations in London: Two hundred years ago, on 30 April 1799, the medical service chief of Lower Austria, Dr. Paskal Joseph Ferro, born in Bonn, vaccinated his three children with vaccine which had come in a letter from London. Subsequently the vaccination was introduced in Austria. Before 1800 effective prophylactic immunizations against smallpox were carried out, apart from England, only in Vienna and environs. The first efficient vaccine to reach India also came from Vienna.