No abstract

SUMMARYThe indirect immunofluorescence technique was used to investigate the expression of virus antigens in a Swiss albino mouse strain infected by mouse mammary tumour virus (MMTV). The antisera used were monospecific for: the glycopolypeptides gpI6o and gP47, and the internal polypeptides p28 and p8.In mice infected with milk-borne MMTV, all four antigens were detected in the mammary gland during the first pregnancy and then throughout life, and in mammary tumours. Antigen gpI6o, located at the secretory border of all glandular cells, is shared by the plasma membrane of the mammary cell, whether virusproducing or not, and by the virus envelope, as shown by the use of absorbed antisera. The other three antigens are virus-specific. Anti-P47 serum stained the secretory border of cells whereas the fluorescence related to p28 and p8 consisted of a few large intracytoplasmic spots. The specific antibodies for p28 and p8 were only absorbed by disrupted virions, confirming that these polypeptides are internal antigens.With serial sections of glands from pregnant and old female mice, the alveoli stained with anti-p28 or anti-p8 serum were found to react also with anti-gp47 serum. However, during lactation, the presence of p28 and p8 could not be detected in the alveoli stained with anti-gp47 serum. Thus, infected alveoli express virus antigens differently. In the mammary glands of all mice studied, some alveoli did not display any staining when the latter three antisera were used. The specific antigenic pattern, maintained in differentiated mammary turnouts, became a diffuse and unlocalized staining after transformation into the undifferentiated state.With the exception of the kidney, where gP47 was found in the glomeruli, all other organs of the mouse did not stain with any of the antisera. The presence of gP47 in the glomeruli, probably related to immune-complex deposits, increases with the age of the mouse and is most noticeable in tumour-bearing femalesIn mice free of milk-borne MMTV, examined during the first week of lactation, antigen gP47 could not be detected. Internal antigens pz8 and p8 were detected in nearly all mammary cells as numerous small cytoplasmic dots. This suggests a limited expression of an endogenous virus genome; this expression would be modified when milk-borne virus is produced.

SUMMARYExtracts of various organs, mammary tumours and sera from milk-borne MMTV infected Swiss albino mice of different age, sex and physiological conditions were tested by radioimmunoassay for the presence of gP47, the main envelope polypeptide, and p28, the main core protein of the virus. Except in brain, ovaries and testes, both antigens were found in all organs of old animals and of females after the onset of their first pregnancy. Antigens were not present in organs of weanlings or in whole foetuses. Higher values were found in mammary glands, mammary tumours, epididymis and seminal vesicles. These organs also harboured a greater amount ofgp47 than p28. The serum generally contained gP47 but rarely p28. This indicates that gP47 is not virion-bound in blood. Pregnancy, lactation and especially the presence of mammary tumours increased the concentration of gP47 in serum. The results do not allow localization of target organs of MMTV infection in the interval between ingestion of the virus by the suckling mouse and the first pregnancy. Moreover, results obtained with one group of mice devoid of exogenous virus show that, as endogenous MMTV genome expresses p28, it might account for part of the p28 detected exogenous MMTV-infected mice.

No abstract

Routine typing was performed on a total of 7089 Pseudomonas aeruginosa strains isolated in 16 Belgian hospitals in the period from 1977 to 1986. The annual number of strains received ranged from 318 to 1346. The incidence of serotype O:12 was less than 2% until 1981 when it rose to 4%, steadily increasing to become the predominant serotype in 1984 (22%), 1985 (18%) and 1986 (22%). Since 1980 the O:12 isolates have exhibited characteristic patterns on pyocin and phage typing, 89% of O:12 isolates belonging to pyocin types 1, 39, 43, 45 or 105, whereas only 51% of isolates of other serotypes belonged to those pyocin types. Ninety-three per cent of serotype O:12 isolates belonged to phage types 68/119x, 68 or 119x, or were non-typable, whereas only 24.37% of other serotypes isolates exhibited these phage patterns. These distinctive patterns of pyocin and phage types suggest a high degree of homogeneity within the O:12 strains isolated in recent years in Belgium. Multi-centre or country-wide survey of Pseudomonas aeruginosa strains isolated in hospitals using epidemiological markers may be of value in identifying a sudden increase in epidemic strains.