Single Virus Strain Research Articles

Antigenic relationships of selected strains of infectious pancreatic necrosis virus and European eel virus

Abstract. An antigenic comparison of ten strains of infectious pancreatic necrosis virus (IPNV) and a single strain of European eel virus (EEV) revealed the presence of three distinct groups separable by cross‐neutralization. The 1/r value calculated from the formula r=√r1× r2 (Archetti & Horsfall 1950) was used to divide the virus strains into: group I, which included all six U.S.A. strains: Buhl, Idaho; Reno, Nevada; ATCC VR 299; Powder Mill, New Hampshire; West Buxton, Maine; and Cascade Locks, Oregon: group II, the European strains: ?Honnincthun, France; Sp Denmark; and Bonnamy, France: group III, Ab Denmark and EEV. The group II European strains of IPNV were more closely related to the group I U.S.A. strains than to those viruses in group III. European eel virus (EEV) was antigenically most closely related to the Ab strain of IPNV.

The Polypeptide and the DNA Restriction Enzyme Profiles of Spontaneous Isolates of Herpes Simplex Virus Type 1 from Explants of Human Trigeminal, Superior Cervical and Vagus Ganglia

Analysis of the infected cell polypeptides and the DNA restriction profiles of 31 HSV-1 isolates from the trigeminal, superior cervical and vagus ganglia from 17 individuals (12 U.S.A., 2 Japanese, 3 Norwegian) could be classified as 15 different virus strains. With the exception of the three Norwegian isolates which gave identical profiles, virus isolates from the ganglia of different individuals could all be distinguished from one another. In contrast virus isolates from the trigeminal, superior cervical and vagus ganglia of the same individual, or virus isolates from the left and right ganglia of the same individual or multiple isolates from different explants of a single ganglion were indistinguishable. In conclusion, a single virus strain infects each individual initially and virus descended from this event subsequently infects and becomes latent in different cells of the same ganglion as well as in different ganglia.

Comparative Effects of Host and Viral Factors on Early Pathogenesis of Marek's Disease

A series of experiments on the early pathogenesis of Marek's disease was conducted according to a uniform scheme. In each experiment, there was a single variable-age, genetic strain, or virus strain. Virus assays from spleen, buffy coat, and bone marrow, and fluorescent antibody tests on spleen, bursa of Fabricius, and thymus were conducted on five birds per group daily from the 3rd through the 10th day postinoculation. From these data, it was apparent that the response could be divided into two periods: 4 to 6 days = early; 8 to 10 days = late. Serological tests showed all groups except the 1-day-old group to have neutralizing antibody by the end of the 10-day period. With few exceptions, none of the variables tested exerted any appreciable influence on the level of virus growth in spleen, bursa, or thymus during the early period. High levels of infection occurred in all birds during that period. Changes in infection pattern which occurred during the late period were significant and could be correlated with occurrence of Marek's disease in test samples of birds held until 7 weeks after infection. Infectivity levels dropped appreciably in the case of resistant N-line birds given JM virus, and, during the late period, infection levels were significantly higher in GA-infected birds than in those given viruses of lower virulence. Whereas the virus titers during the 8- to 10-day period usually reflected the eventual clinical pattern of Marek's disease, the levels of viral antigen (fluorescent antibody tests) were much less consistent. One further experiment conducted by the same uniform scheme demonstrated no significant effects on early pathogenesis or course of Marek's disease in birds given continuous oral medication with amino-ureido-sulfone.

Role of virus strains and leaf ontogeny in the production of mosaic patterns by turnip yellow mosaic virus

The production of islands of different types of tissue containing virus in Chinese cabbage plants systemically infected with TYMV is dependent on the existence of various strains of the virus which are present in the inoculum or arise by mutation in the plant. Different virus strains which cause recognizably distinct pathological changes in the chloroplasts are localized in various islands of tissue. Examination by light microscopy shows that in many parts of a leaf showing a macroscopic mosaic there is also a microscopic mosaic in which different cell layers within the leaf are affected differently by the virus. The close parallels between the distribution of cell types in TYMV infection and in leaves containing plastid mutants lend support to the view that the various islands of tissue in the mosaic induced by TYMV represent clones of cells originating from a dividing cell infected by a single strain of virus. Disks of dark green tissue from leaves showing mosaic and floated on water or various media did not produce virus, but were capable of massive synthesis of 83 S ribosomes under the influence of kinetin.

Further studies on the kinetic serum-neutralization (McBride) test for polioviruses.

Groups of 12 roosters were immunized with four type 1 poliovirus strains, Sabin's reference, one "vaccinee", one "vaccine-contact", and one "wild" strain, respectively. Sera were collected 1 week after the third, the fifth, and the seventh immunizing dose and tested simultaneously in the McBride antigenic test against the four virus strains used for immunization and against another "wild" strain. The immunization schedules of five or seven doses of virus inoculum resulted in specific sera of high antibody titers and were found suitable for kinetic neutralization studies. The statistical analysis of the test results demonstrated that antigenic differences among virus strains accounted for the largest single source of variation, and although the variation attributable to individual roosters was significant, it was small in comparison with that due to virus strain differences. These data indicated that a group of four roosters should be immunized with a single virus strain using five or seven doses; the mean value of the neutralization rate constants of the four individual antisera will well characterize the intratypic antigenic differences between virus strains.

Combination of characters (drug resistance) in a single strain of psittacosis virus.

Combination of characters (drug resistance) in a single strain of psittacosis virus.

The Titration of Poliomyelitic Virus Containing Tissue

Abstract There is reason to believe that during the serial transmission of a single strain of poliomyelitis virus through monkeys, periodic changes in its infectivity occur (Flexner and Lewis (1), Flexner et al. (2), Flexner and Amoss (3)). It is not surprising, therefore, that the infectivity of the different strains in common use show no agreement. This is revealed in the experiences of various workers. Amoss (4), for example, states that as little as 0.001 cc. of a 5 per cent emulsion can infect monkeys, while Fair-brother (5), infected with 0.003 cc. and Stewart and Rhoads (6) with 0.005 cc. of a 5 per cent emulsion. On the other hand, Shaughnessy, et al. (7) and Rosenow (8) failed to infect monkeys with as much as 1 cc. of a 5 per cent emulsion. Furthermore, as is shown in an accompanying paper, poliomyelitis virus is not uniformly distributed throughout the brain and cord.