Staphylococcus aureus: study of genomic similarity of strains isolated in veterinary pathology using amplified fragment length polymorphism (AFLP).

Staphylococcus aureus is a widespread pathogen causing infections in different animal species. The extensive use of antibiotics, particularly methicillin, causes the rise of antibiotic-resistant strains (MRSA). In order to verify the epidemiology and genetic relatedness among MRSA and sensible strains (MSSA), an accurate fingerprinting technique, the amplified fragment length polymorphism (AFLP), was carried out. The isolates were cultured, subdivided on MRSA and MSSA and submitted for the genomic DNA extraction that was utilized for AFLP. The data were analysed for genetic similarity using the Dice coefficient. The results of genomic analysis among MRSA and MSSA and within them revealed that the major component of variation was due to variation within strains (82.12%), while variance among strains was lower (17.88%). The low level of genomic similarity found among S. aureus strains implies high level of genetic diversity. Different similarity was found as well in all strains independently of the source.

Internalization of Candida albicans and cytoskeletal organization in macrophages and fibroblasts treated with concanavalin A.

This paper investigates the ability of macrophages and of non-typically phagocitic cells such as fibroblasts to internalize 51Cr-labelled C. albicans in presence or in absence of lectin concanavalin A (Con A). The results obtained demonstrate that fibroblasts are also able to internalize C. albicans and that this property is potentiated by the presence of Con A. Lectin modifies only the phenotype of the fibroblast, which, poorly attached to the substrate, is globular in shape. Despite reduced cellular spreading, phagocytosis is stimulated by the lectin. In both cell populations, changes in the organization of some cytoskeletal proteins such as tubulin, actin and alpha-actinin are evident during the C. albicans infection; such rearrangements are more evident and longlasting in the fibroblasts treated with Con A.

Systemic infection with Herpes bovis virus 2 evokes a biphasic immune response in the mouse.

We evaluated the effects of systemic infection by Herpes bovis virus 2 (HBV-2) on a murine experimental system. We provide evidence that such infection is lethal for the immunocompromised but not for the immunocompetent mouse in which a biphasic immune response is elicited. In particular, 1 day post-infection, we observed a rapid transient depression induced by the virus, as documented by a decrease in peripheral leukocyte counts, mitogenic spleen cell response and resistance to a secondary microbial challenge. Later, HBV-2 infection boosted cytokine secretion and enhanced antimicrobial and antitumoral activities by the splenic district. In conclusion, our experimental model discloses some immunological aspects underlying the complex host-virus interaction.

Experimental model of type IV Streptococcus agalactiae (group B streptococcus) infection in mice with early development of septic arthritis.

We have established an experimental murine model to gain insight into the pathogenicity and clinical features of type IV group B streptococcus (GBS) infections. Adult CD-1 mice were challenged intravenously with 10(7) type IV GBS cells, inducing systemic invasion. Most of the animals were able to clear the infection from the blood, brain, and lungs within 2 weeks and from the spleen and liver within 1 month. However, the animals were unable to clear the microorganism from the joints and kidneys during the 60-day observation period. About 80% of the mice challenged intravenously with type IV GBS manifested early septic arthritis, which evolved from an acute exudative synovitis to permanent lesions characterized by irreversible joint damage and ankylosis. Induction of persistent septic arthritis was dependent on the number and viability of microorganisms inoculated and was unrelated to the strain of type IV GBS and the growth phase of the inoculum. Type-specific antibodies of both immunoglobulin M and G classes could be detected by agglutination and enzyme-linked immunosorbent assay from days 7 and 14, respectively; immunoglobulin G antibodies persisted for more than 40 days. Complexes of antibodies and group- and type-specific antigens were detected in mouse sera 24 h after infection and persisted up to day 22. These results were obtained an experimental model of type IV GBS chronic infection with early development of septic arthritis, which could be useful in future studies of pathogenicity and immune mechanisms involved in the host resistance to this microorganism.

Generation of macrophage cell line from fresh bone marrow cells with a myc/raf recombinant retrovirus.

We have studied the effects of infection of fresh murine bone marrow (BM) cells by recombinant retroviruses carrying v-raf and v-myc oncogenes, either alone or in combination. Viruses containing v-raf or v-myc alone failed to induce BM proliferation in 24 out of 27 experiments performed so far, only the J2 virus containing both v-raf and v-myc oncogenes induced BM proliferation. Exogenous growth factors (GF) were not required to sustain the mitogenic effect of J2 virus. Infection with retroviruses carrying only v-raf or v-myc did not induce BM cell growth, indicating that co-expression of the two oncogenes was needed to provide the mitogenic signal(s) for BM proliferation. The kinetics of growth of the J2 virus-infected cells (J2 cells) were characteristically biphasic. The initial burst of proliferation was always followed by a quiescent phase culminating in cell death, which could not be reversed by addition of exogenous GF. In contrast, active proliferation of the quiescent monolayers could be restored by addition of dextran-based beads to the cultures, showing that the growth arrest of J2 cells was a reversible process. J2 cells actively growing in the presence of CT-beads could be expanded and cloned and subsequently grew continuously independent of the CT-beads. Eighteen clones obtained from different infections were all macrophages (M phi) by morphological criteria and all of them expressed the same membrane phenotype compatible with M phi, demonstrating that J2 virus infection leads to immortalization of the same BM-derived monocytic subpopulation. When injected in vivo, J2 cells produced histiocytic tumors in nude mice, but did not grow in immunocompetent syngeneic mice. The cells induced to proliferate in vitro in response to J2 virus infection appeared to be limited to the BM compartment, since spleen cells, thymocytes, peritoneal M phi and liver large granular lymphocytes did not grow in vitro in response to J2 virus. The immortalization of BM cells by J2 virus infection represents a novel reproducible experimental system to deliberately generate M phi lines, which proliferate in response to viral oncogenes and do not require exogenous GF to initiate or to sustain their continuous proliferation.

Immune response to trivalent inactivated influenza vaccine in young and elderly subjects.

The antibody response (determined using the single radial haemolysis in gel technique) to inactivated whole-virion trivalent influenza vaccine [A/Leningrad/360/86(H3N2), A/Taiwan/5/87 and B/Ann Arbor/1/86], recommended for the 1987-88 winter season in Italy, in 49 elderly (age greater than or equal to 60 years) subjects was compared with the response in 23 young adult (age less than 60 years) volunteers. The subjects were prevalently healthy and a high percentage of young and old people had been repeatedly immunized against influenza in previous years. No significant differences were detected among age groups; moreover, the immune response measured by seroconversion or by a significant rise in antibody titre was constantly low.

[Sero-epidemiologic studies of acute hepatitis A in Umbria: behavior of IgM anti-HAV antibodies]. / Ricerche sieroepidemiologiche sull'epatite acuta A in Umbria: comportamento degli anticorpi IgM anti-HAV.

The diagnosis of acute Hepatitis A is made when antibodies anti-HAV, of the IgM class, are detected in the blood. The Authors have examined with RIA test (HAVAB-M, Abbott) 298 samples of serum from patients with acute non B hepatitis, non drug abusers, also they had not received blood transfusions; as control they examined 41 sera from patients with hepatitis B, 29 sera from patients with non B hepatitis and drug addiction, 25 sera from patients with transfusional non B hepatitis and 37 sera from healthy persons. From the first group (298 patients) 47% were positive for anti-HAV antibodies IgM class; the greatest incidence of positivity (80%) was detected in the class age 0-10 years. In the control groups only in one serum positivity was evidenced and the patient was 22 years old, drug addicted with non B acute hepatitis and with previous episodes of acute hepatitis.

Hydatidosis: a first approach for serological standardization.

Hydatid fluids were collected in three continents and used as antigens against both human E. granulosus and E. multilocularis hydatidosis-positive sera collected in the same countries, in ELISA. The sensitivity of the antigens was good for all sera examined and this confirms the existence of common antigens, which is particularly marked in the 0.8M fraction of Italian hydatid fluid.

[Epidemiological results in recovered cases of viral hepatitis at the Infectious Disease Clinic of the University of Perugia from 1971 to 1978]. / Indagine epidemiologica sui casi di epatite virale ricoverati nella Clinica di Malattie Infettive dell'Università di Perugia dal 1971 al 1978.

A retrospective epidemiological survey on patients admitted for hepatitis to the Infectious Disease Institute of Perugia University was undertaken. 255 out of 610 patients, examined during the 1971-1978 period, had type B hepatitis. The incidence of post transfusional hepatitis was 15.7%, while the disease showed significant increase in drug addict patients and in hospital staff. HBsAg was positive in 40 of 94 patients (43.7%) with post-transfusional hepatitis.

[Levels of specific antibodies against poliomyelitis virus and degree of immune protection in Umbria population]. / Livelli di anticorpi specifici per i virus poliomielitici e grado di protezione immunitaria nella popolazione Umbra.

The Authors studied neutralizing antibodies against poliomyelitis wild viruses in a sample of Umbria population. The number of seronegative results for each virus strain was very low (less than 1%). The geometric mean titres were 21.07, 26.72, 19.13 for poliovirus types 1, 2, 3, respectively. The results of this seroepidemiological study shows that the Umbria population is satisfactory protected against the poliomyelitis.

A murine oncornavirus marker in adenovirus 7-transformed mouse cells.

The presence of oncornavirus particles in BALB/c mouse cells transformed by adenovirus 7 was investigated. The particles detected had a buoyant density of 1.16 g/cm3; both p30 and adenovirus T-specific immunofluorescence was demonstrated in the cell cytoplasm. No C-particles were shown by the electron microscope.

Effect of cyclophosphamide on syngeneic transplantation of adenovirus 12-transformed tumor cells in C3H/he mice.

We tested the cyclophosphamide effects against the growth of adenovirus-transformed cells and the subsequent tumor development in the syngeneic host. Cyclophosphamide did not show any effect on the tumor evolution when injected 24 and 6 hours before cell implantation. Cyclophosphamide injected 24 or 39 hours after cell implantation prevented or retarded the tumor growth. In mice bearing palpable tumors, it induced their complete regression in 85,7% of the animals, but did not effect the development of the homograft immunity.

Sialic acid content in four cell strains transformed by adenoviruses and/or SV40.

The sialic acid content in hamster cells primarily transformed by adenovirus was found lower than in cells transformed by papovavirus SV40. Intermediate concentrations were shown in a cell strain transformed by an adenovirus-SV40 hybrid. An adenovirus 19 - transformed cell strain derived from the NIL-2 hamster cell line, adapted to unlimited growth in vitro prior to the exposure to the adenovirus, revealed a high content of sialic acid. The concentration of sialic acid in cells transformed by DNA-viruses may depend both on the transforming virus and on the preceding history of the cell line. The tumors revealed more sialic acid than the in vitro cultures derived from the same cell strains. This finding is discussed.

[Human seroepidemiology Polyoma virus BK in Umbria]. / Sieroepidemiologia umana del polyoma virus BK in Umbria

A serological study on the antibody level against BK virus in healthy population and respiratory patients in Umbria was performed. Serum samples of 465 healthy people and 155 patients grouped by age, were tested using HAI. 47% of all sera was positive. The epidemiological implications are discussed.