Presence of type C virus particles and their aberrant form in mammary carcinoma of a

Acta Medica Okayama

Volume20,Issue4 1966 Article2

A

^UGUST

1966

Presence of type C virus particles and their aberrant form in mammary carcinoma of a

strain C58 mouse

Shinya Suzuki

^∗

Zensuke Ota

^†

Kiyoshi Hiraki

^‡

∗Okayama University,

†Okayama University,

‡Okayama University,

Copyright c1999 OKAYAMA UNIVERSITY MEDICAL SCHOOL. All rights reserved.

strain C58 mouse ^∗

Shinya Suzuki, Zensuke Ota, and Kiyoshi Hiraki

Abstract

Detailed morphologic characteristics of type C virus particles observed in an X-ray-induced C58 mammary tumor and its transplants have been described. The particles are round and 75 to 100 mµin diameter, containing an electrondense nucleoid 60 to 70 mµin diameter. By the negative staining, they do not show obvious spines. Two abnormal types of particles, i. e. cylindrical and aberrant forms have been observed.

∗PMID: 4292109 [PubMed - indexed for MEDLINE] Copyright cOKAYAMA UNIVERSITY MEDICAL SCHOOL

Acta Merl. Okayama 20, 155-158 (1966)

PRESENCE OF TYPE C VIRUS PARTICLES AND THEIR ABERRANT FORM IN MAMMARY CARCINOMA OF

A STRAIN C58 MOUSE

Shinya SUZUKI, ?:ensuke OTA and Kiyoshi HIRAKI

Department of Internal Medicine, Okoyama University Medical School Okayoma, Japan (Director: Prof. K. Hiraki)

Received for publication, May 20, 1966

Type B virus particles have been demonstrated in mammary tumors of various inbred mouse strains by electron microscopy and considered to be the causative agents of the tumors. Authors¹ have recently reported that type C virus particles, resembling mouse leukemia particles were found in mammary carcinoma arising in a high leukemic strain C58 mouse after X-ray irradiation.

HAIRSTONE and associates² have observed similar virus particles in mammary tumors of strain A mice. They have, however, assumed that particles in the strain A tumors represent an immature form of the standard B particle, since the size of the total particle is larger than leukemia particles and it has 100

A

spines on the envelope as revealed by negative staining. The present paper is concerned with further detailed morphologic study on virus particles in the strain C58 mammary tumors.

MATERIALS AND METHODS

The origin of the present tumor has been described in the previous paper^1• The tumor has been maintained by serial subcutaneous cell-graft in C58 mice less than 4 months old. Tissues from the original tumor and its transplants of the 1st to 7th generation were prepared for electron microscopy. They were fixed in buffered 1

%

osmium tetroxide solution, dehydrated in graded alcohol solutions, embedded in a mixture of methyl and butyl methacrylates and sectioned with a Leitz ultramicrotome. Thin sections were double stained in saturated uranyl acetate solution and in Raynold's solutionS. For negative con- trast electron micrographs, virus particles were examined ~ccording to the method described by PARSONS^6•

RESULTS

Figure 1 illustrates an acinar space of the original tumor filled with nume- rous virus particles and fibrils. An epithelial cell with microvilli lies at lower

155

1 Suzuki et al.: Presence of type C virus particles and their aberrant form in

Produced by The Berkeley Electronic Press, 1966

156 ^{S. SUZUKI, Z. OTA and K. HIRAKI}

Type C Virus in Mammary Carcinoma 157 portion of the field. The particles consist of a moderately electron-dense, centrally located nucleoid 60 to 70mp. in diameter, contained within a dense shell ranging 75 to 100mf!. in diameter. Similar virus particles have been observed in transplants of all generations. However, neither extracellular type B or intracellular type A virus particles have been encountered.

Figure 2 shows virus particles at higher magnification. A few spines 100

A

long are seen covering the external coat of the particles.

When negatively stained, the particles are round, ranging 100 to 190 m,l.

in diameter and do not show obvious spines on the envelope (Fig. 3). Some of them display an empty center corresponding to the nucleoid.

Figure 4 illustrates the profiles of cylindrical forms of the virus present in a degenerated portion of the transplant of the 3rd generation. They are com- posed of an outer membrane approximately 90mll.in diameter and an internal dense structure about 60mll.in diameter. They extend to more than 400m,fl in length.

Figure 5 shows virus particles with an unusual internal structure. These particles contain a few dense fibrils instead of the nucleoid. A similar particle is seen in Fig. 1.

DISCUSSION

The morphologic characteristics of virus particles in the C58 mammary tumors have led us to conclude that they are type C virus particles and not a variant of the type B particles. The size and internal structure of the particles observed in thin sections are consistent with the type C virus particle and when negatively stained, they do not show obvious spines. The cylindrical form of type B particles has not been described in the literature to our best knowledge. Although the spines on the envelope are reported to be obscure in most of papers concerning type C particles, they have been observed in leuke- mia viruses⁵•6

•

The fibrils within virus particles can be abnormally-arranged nucleoprotein complex, but we rather presume that they are the same fibrils as seen in the acinar space (Fig. 1) and that they are accidentally inserted into some of the particles in the process of budding at the microvilli. Similar aberrantly-formed

Fig. 1 Portion of an acinar space containing type C virus particles and fibrils. Arrow in- dicates an aberrant type C virus particle. Magnification: X70,000

Fig. 2 Type C virus particles at higher magnification. Particles are covered with spines.

Magnification: X150, 000

Fig. 3 Negative contrast micrograph of type C virus particles. Magnification: X160, 000 F!g. 4 Profiles of cylindrical forms. Magnification: X60,000

Fig. 5 Three aberrant type C particles containing fibrils. Magnification: X87,500

3 Suzuki et al.: Presence of type C virus particles and their aberrant form in

Produced by The Berkeley Electronic Press, 1966

158 S. SUZUKI, Z. OTA andK. HIRAKI

virus particles have been reported in nephroblastoma induced with BAI strain A avian tumor virus^7•

The constant presence of numerous type C virus particles in tumor tissues throughout serial cell-graft may suggest that this virus is responsible for the carcinogenesis of the C58 mammary carcinoma.

SUMMARY

Detailed morphologic characteristics of type C virus particles observed in an X-ray-induced C58 mammary tumor and its transplants have been described.

The particles are round and 75 to 100mp.in diameter, containing an electron- dense nucleoid .60 to 70mp. in diameter. By the negative staining, they do not show obvious spines.

Two abnormal types of particles, i. e. cylindrical and aberrant forms have been observed.

ACKNOWLEDGEMENT

The authors wish to express their thanks to Mr. N. HAYASHI and Mr. N. KISHIMOTO for their assistance with electron microscopy.

REFERENCES

1. HIRAKI, K., OTA, Z., S. and MUGURUMA, M.: Electron microscopic study of mammary cancer developed in a high leukemic strain C58 mice. Gann 56, 81, 1965

2. HAIRSTONE, M. A., LYONS, M.J. and MOORE, D. H.: Morphological distinctiion of type B virus particles in mammary tumors of strain A mice. Virology 23, 294, 1964

3. RAYNOLD3, E. S.: The use of lead citrate at high pH as electron-opaque stain in electron microscope. ]. Cell Bioi. 17, 208, 1963

4. PARSONS, D. F.: Negative staining of thinly spread cells and associated virus. ]. Biophys.

Biockem. Cytol. 16, 620, 1963

5. PARSONS, D. F.: Structure of the gross leukemia virus. ]. Natl. Cancer Inst. 30, 569, 1963

6. ZEIGEL, R. F._~and RAUSCHER, F.R.: Electron microscopic and bioassay studies on a murine leukemia virus (RAUSCHER). 1. Effects of physiochemical treatments on the morphology and biological activity of the virus. ]. Natl. Cancer Inst. 32, 1277, 1964