Studies on the specificity of the vaccine effect elicited by inactivated simian immunodeficiency virus.

Inactivated, partially purified simian immunodeficiency virus (SIVmac) protected macaques from intravenous challenge with homologous and heterologous strains of SIV that had been grown on human cells but no protection against challenge with monkey peripheral blood mononuclear cell-grown SIVmac was afforded. Human immunodeficiency virus type 1 prepared in an analogous way to the SIVmac vaccine on the C8166 human T cell line protected macaques against challenge with human cell-grown SIVmac. These results suggest that protection may be mediated by xenoimmunization with the vaccine cell substrate proteins. All vaccinated macaques had anti-cell antibodies. Major reactivity to MHC class I antigens was found as well as to a 70-kD protein detectable only under nonreducing conditions.

Covalent linkage of carboxypeptidase G2 to soluble dextrans--II. In vivo distribution and fate of conjugates.

The in vivo fate of the therapeutic enzyme, carboxypeptidase G2 (CPG2) in native form and covalently-linked to soluble dextrans was studied in the mouse using radiolabelled compounds. Clearance, from the blood, of all compounds tested was found to be as intact, active material, whilst excreted radiolabel was associated in all cases with low molecular weight substances. The clearance and excretion rates of native CPG2 were found to balance, but this was not so for dextran-CPG2 conjugate or CNBr-activated dextran. Tissue distribution studies demonstrated that there was little or no tissue uptake of native CPG2, whereas dextran-CPG2 conjugate, and CNBr-activated dextran were retained in the liver. Within the liver, the CPG2 component of dextran-CPG2 conjugate was degraded more rapidly than the dextran moiety. Blockade of reticulo-endothelial system (RES) led to increased half-lives of dextran CPG2 conjugate and CNBr-activated dextran, demonstrating the involvement of the RES in the clearance of these compounds. Impairment of RES activity did not affect the clearance rate of native CPG2. These results are discussed in relation to the potential use of dextran-CPG2 conjugates in cancer chemotherapy.

Congo-Crimean haemorrhagic fever in Dubai: histopathological studies.

Necropsies were carried out on two patients who died of Congo-Crimean haemorrhagic fever (C-CHF) in Dubai. The diagnosis was confirmed by isolation of C-CHF virus from the liver. Histopathological changes included extensive cellular necrosis and haemorrhage in the liver, necrosis and lymphoid depletion in the spleen, congestion and oedema formation in the lungs, and haemorrhage in a number of other organs.

Comparative in vitro activity of lomefloxacin, a difluoro-quinolone.

Lomefloxacin is a new difluoro-quinolone. In this study, we have determined the in vitro activity of lomefloxacin against a wide range of clinical bacterial isolates and compared it with that of other fluoro-quinolones and some unrelated antimicrobials. Lomefloxacin was very active against Enterobacteriaceae (MIC90, 0.5 micrograms/ml) with activity comparable to that of ofloxacin (MIC90, 0.25 micrograms/ml). Lomefloxacin was moderately active against isolates of Pseudomonas aeruginosa (MIC90, 4 micrograms/ml), and again the activity was comparable to ofloxacin (MIC90, 4 micrograms/ml) but was eightfold less than ciprofloxacin (MIC90, 0.5 micrograms/ml). Lomefloxacin was also active against isolates of Staphylococcus aureus (MIC90, 1 micrograms/ml), irrespective of methicillin susceptibility, and this activity was most comparable to ofloxacin (MIC90, 0.5 micrograms/ml) and ciprofloxacin (MIC90, 0.5 micrograms/ml). Lomefloxacin was fourfold less active than either ofloxacin or ciprofloxacin against isolates of Enterococcus faecalis (MIC90, 8 micrograms/ml) and Streptococcus pneumoniae (MIC90, 8 micrograms/ml). In common with ofloxacin and ciprofloxacin, lomefloxacin was very active against isolates of Neisseria spp. (MIC90, less than or equal to 0.06 micrograms/ml), Haemophilus spp. (MIC90, less than or equal to 0.06 micrograms/ml), Legionella spp. (MIC90, less than or equal to 0.06 micrograms/ml), Vibrio spp. (MIC90, less than or equal to 0.06 micrograms/ml), and Campylobacter jejuni (MIC90, 1 microgram/ml). Lomefloxacin showed poor activity against isolates of Bacteroides spp. (MIC90, 16 micrograms/ml) or Clostridium difficile MIC90, 32 micrograms/ml) and was only moderately active against isolates of Clostridium perfringens (MIC90, 2 micrograms/ml), Peptostreptococcus spp. (MIC90, 4 micrograms/ml), Chlamydia trachomatis (MIC90, 4 micrograms/ml), Mycoplasma hominis (MIC90, 2 micrograms/ml), and Urea-plasma urealyticum (MIC90, 8 micrograms/ml). Lomefloxacin was found to be bactericidal at concentrations generally close to the MIC with greater than 3 log10 reduction in viability of exponentially dividing cultures of Escherichia coli and S. aureus within 5 hr of exposure to concentrations at eight times the MIC. These results indicate a potential clinical role for lomefloxacin in the treatment of genitourinary tract infections caused by Gram-positive and Gram-negative bacteria, respiratory tract infections caused by susceptible organisms, and soft tissue infections caused by S. aureus.

Experimental infection of monkeys with Herpesvirus suis (Aujeszky's-disease virus).

Monkeys were infected intranasally with Herpesvirus suis. After an incubation period of 7 to 13 days the animals became acutely ill and rapidly died. Clinical signs included salivation, incoordination, ataxia and epileptiform convulsions, but not pruritus. Histopathological changes were confined to the central nervous system, and consisted of destruction of neurones with the formation of intranuclear inclusion bodies, gliosis and perivascular cuffing. Virus was isolated from the brain and spinal cord in the later stages of the illness but neutralising antibodies were not detected in serum. The distribution of lesions indicated direct spread of virus from the inoculation site along cranial nerves to the brain.

Isolation of a gastric campylobacter-like organism from the stomach of four rhesus monkeys, and identification as Campylobacter pylori.

Campylobacter-like organisms, isolated from the gastric antrum of Rhesus monkeys, were compared with Campylobacter jejuni and C. pylori. They were similar to C. pylori by light microscopy, in ultrastructural morphology, in enzymic, fatty-acid-methyl-ester, and protein-profile analysis, and in antigenic reactivity with rabbit antisera to C. jejuni and C. pylori and with C. pylori-specific monoclonal antibody. Because this natural infection of the Rhesus monkey is associated with chronic gastritis, resembling the disease in humans colonised with C. pylori, we recommend the animal as a model for the investigation of human gastritis.

Pathological and biochemical features of Legionella pneumophila infection in guinea-pigs.

The main pathological feature of experimental legionellosis produced by the intraperitoneal inoculation of guinea-pigs was a fibrinopurulent peritonitis, especially over the liver and spleen. Foci of necrosis were present in these organs from the second to seventh day after infection. Early biochemical changes in the serum included significant decreases in the concentration of zinc and iron, and increases in copper and triglycerides. Phenylalanine to tyrosine ratios increased strikingly, but free amino acid decreased slightly. The total protein concentration did not change, but acute-phase proteins increased. Serum lysozyme activity increased as leucocytosis developed but fell during the subsequent leucopenia. In the later stages of the disease the activity of alkaline phosphatase, gamma-glutamyl transpeptidase, and creatine kinase decreased; that of dehydrogenases and transaminase increased.

Isolation of colonial variants of Bacteroides gingivalis W50 with a reduced virulence.

The spontaneous appearance of unusual colony forms was observed during prolonged growth of Bacteroides gingivalis W50 in a chemostat. Two variants were selected for further study which could be distinguished from the parent strain by the rate and intensity of pigmentation of their colonies. For example, after anaerobic incubation for 14 days, variant W50/BR1 produced brown colonies whereas those of the parent strain were black; in contrast, variant W50/BE1 did not show signs of pigmentation until incubation had continued for 21 days. In subsequent studies in the chemostat, variant W50/BE1 bred true even after prolonged growth whereas other colony forms appeared after incubation of variant W50/BR1 for 14 days. The relatedness of W50/BR1 and W50/BE1 to the parent strain was confirmed by comparisons of the whole-cell fatty-acid profiles, the patterns of pre-formed enzymes and by the metabolic end products after growth. However, the variants did differ from the parent strain in their virulence in a mouse pathogenicity model. The parent strain killed all mice given infective doses greater than 5 x 10(8) cfu whereas W50/BR1 was much less virulent (2 out of 10 mice killed and higher infective doses needed for higher mortality rates) and W50/BE1 was avirulent at all infective doses tested.

The use of the polymerase chain reaction for the detection of Simian immunodeficiency virus in experimentally infected macaques.

A rapid, non-radioactive assay for the detection of proviral Simian immunodeficiency virus (SIV) in tissue-culture cells is described. The assay is based on the co-amplification of the SIV env and gag genes by the polymerase chain reaction (PCR). When the gag PCR product is blotted onto a nylon membrane and hybridised to a radioactive oligonucleotide probe, the assay can also be used to detect the SIV gag gene in DNA isolated directly from experimentally infected cynomolgus macaque lymphocytes. This provides a valuable assay for the presence of proviral SIV during animal trials of AIDS vaccines and chemotherapeutics.

Bacterial infection (Legionella pneumophila) stimulates fever, metabolic rate and brown adipose tissue activity in the guinea pig.

The objective of this study was to assess whether bacterial infection stimulates oxygen consumption and brown adipose tissue (BAT) activity. Guinea pigs infected with Legionella pneumophila showed marked fever and a significant (33%) increase in resting oxygen consumption (VO2), 24h after infection. At this time, food intake and body weight were normal and the in vitro thermogenic activity of BAT taken from infected animals was elevated by 64% above that of control guinea pigs. VO2 and BAT activity fell to control values by 48h as infected animals became moribund and over this period food intake was markedly reduced.

Antibiotic therapy of experimental airborne Legionnaires' disease.

The efficacy of erythromycin, gentamicin and rifampicin has been compared in the treatment of experimental airborne Legionnaires' disease in guinea-pigs. Evaluation was based on survival of animals after 1LD50 or 10LD50 infection, on numbers of Legionella pneumophila in the lungs and on the extent of histopathological lesions. All three drugs were effective in increasing survival in 1LD50 infections, but only rifampicin gave any protection against 10LD50 infection. Rifampicin was the most effective agent in eliminating viable L. pneumophila from the lungs and also in preventing pulmonary lesions.

Studies on ciprofloxacin therapy of experimental Legionnaires' disease.

The concentration of ciprofloxacin in the serum and tissues of normal guinea-pigs was monitored after intramuscular and oral administration. Significant concentrations were attained in the kidneys, but higher doses were required before serum and lung concentrations became measurable. Ciprofloxacin, given parenterally, prevented pyrexia and death of guinea-pigs infected by aerosols of Legionella pneumophila. Although it markedly reduced the number of bacteria in the lungs, it did not prevent the development of pulmonary lesions. Ciprofloxacin administered orally was not so effective in preventing death, although pyrexia was prevented and numbers of bacteria in the lungs of guinea-pigs were reduced. The low minimum inhibitory and bactericidal concentrations of ciprofloxacin against L. pneumophila together with the in vivo results observed suggest that this antibiotic could be of value in the treatment of human beings suffering from Legionnaires' disease.

A high performance liquid chromatography method for the determination of FCE 22101, a novel penem antimicrobial, in serum.

FCE 22101 (sodium [5R, 6S, 8R]-6-alpha-hydroxyethyl-2-carbamoyloxymethyl-2- penem-3-carboxylate) is a new penem antimicrobial with a broad spectrum of activity. In order to investigate the pharmacokinetics of FCE 22101 in human volunteers, a high performance liquid chromatographic assay has been developed for determining concentrations of FCE 22101 in serum. Serum samples were deproteinised with an equal volume of acetonitrile followed by centrifugation. The supernatant was then diluted with an equal volume of 0.05 M phosphate buffer (pH 7.0) and 50 microliters was applied to the separation column. Chromatographic separation of FCE 22101 was achieved using an SP8700 solvent delivery system (Spectra-Physics), an SP8780XR autosampler (Spectra-Physics) and a reverse-phase C18 mu-BondaPak column (8 X 100 mm) radially compressed in a Z module (Millipore, UK). The mobile phase consisted of a water, methanol and orthophosphoric acid mixture (74:25:1), which was filtered through a 0.22 micron filter and de-gassed under vacuum prior to use. The flow rate was 1.4 ml/min and FCE 22101 was detected in the column eluant using an LC871 UV-Vis detector set at 318 nm. The data were analysed using an SP4270 integrator (Spectra-Physics). The lower limit of sensitivity of the assay method was 0.8 mg/l and recovery from deproteinised serum was of the order of 70%. Intra-assay variation was less than 5% and inter-assay variation was less than 10%.

Comparative in vitro activity of ciprofloxacin and other unrelated antimicrobials against bacterial respiratory tract pathogens.

Ciprofloxacin is a new fluorinated 4-quinolone with a broad spectrum of antimicrobial activity which includes both Gram-negative and Gram-positive bacteria. In this study the in vitro activity of ciprofloxacin has been determined against bacteria associated with respiratory tract infections and compared with that of other antimicrobial agents used in the therapy of such infections. Ciprofloxacin (MIC90 0.008 mg/l) was highly active against Haemophilus influenzae, including isolates producing beta-lactamase which were resistant to amoxycillin. Ciprofloxacin (MIC90 0.06 mg/l) was also highly active against Branhamella catarrhalis, again including those isolates resistant to amoxycillin as a result of beta-lactamase production. Isolates of Streptococcus pneumoniae were less susceptible to ciprofloxacin (MIC90 2 mg/l) but were highly susceptible to amoxycillin (MIC90 less than 0.12 mg/l) and erythromycin (MIC90 0.25 mg/l). Isolates of Klebsiella aerogenes were highly susceptible to ciprofloxacin (MIC90 0.06 mg/l) but much less so to amoxycillin, sulfamethoxazole, trimethoprim, oxytetracycline and erythromycin. Ciprofloxacin (MIC90 0.5 mg/l) was very active against Staphylococcus aureus, including those isolates resistant to amoxycillin and flucloxacillin, and against Mycoplasma pneumoniae. Together with rifampicin and erythromycin, ciprofloxacin was highly active against Legionella pneumophila (MIC90 0.015 mg/l). These results suggest that clinical evaluation of ciprofloxacin in the treatment of respiratory tract infections is justified.

Undifferentiated carcinoma of the nasal tissues in the common marmoset.

The occurrence of undifferentiated carcinoma of the nasal tissues in 3 adult marmosets is described. The tumours appeared to arise from the respiratory epithelium of the turbinate bones and nasal septum. They were poorly differentiated, invaded the paranasal sinuses and hard palate and metastasized to the lungs or liver.

Biochemical and pathological changes in experimental phycomycosis.

Intravenous inoculation of rabbits with spores of Absidia corymbifera strain V.73/8 produced acute phycomycosis and death within 2 to 10 days. Cultural and microscopical examination showed that fungal infection was widespread and involved most organ systems but with particularly extensive lesions developing in the kidneys. The progress of the infection was associated with a raised leucocyte count, an increasing erythrocyte sedimentation rate and significant changes in serum biochemistry. The latter included a decrease in serum iron, zinc, alkaline phosphatase and gamma-glutamyl transpeptidase concentrations but an increase in the synthesis of acute phase proteins and in the phenylalanine:tyrosine ratio and in serum concentrations of copper, magnesium, potassium, lactate dehydrogenase and triglycerides. The serum urea concentration increased substantially during the terminal phase of infection.

Pathological changes in the reproductive tract of male rhesus monkeys associated with age and simian AIDS.

The pathological changes associated with ageing and simian immunodeficiency virus (SIV) infection in groups of immature, adult and ageing Rhesus monkeys were studied. Eighty three per cent (5 of 6) of uninfected ageing animals had hyperplasia of the prostate, 33 per cent (2 of 6) had mild prostatitis and in 66 per cent (4 of 6) there were calcified concretions in the seminal vesicles. The testes were normal and showed active spermatogenesis. In the SIV-infected animals, two types of lesion occurred; the most common, in 81 per cent (18 of 22 monkeys), was the presence of focal lymphoid infiltrations in the epididymis, prostate or seminal vesicles. The other was hypospermatogenesis (23 per cent, 4 of 17) with degeneration of seminiferous tubules. Immunocytochemical staining demonstrated that the lymphoid masses contained approximately equal numbers of B and T lymphocytes, but the majority of diffusely scattered cells were T lymphocytes. Staining for SIV antigen identified small numbers of positive lymphocytes and macrophages in all tissues.

Chronic pancreatitis and biliary fibrosis associated with cryptosporidiosis in simian AIDS.

Two Rhesus monkeys infected with simian immunodeficiency virus for 15 and 24 months developed generalized oedema and one became jaundiced. At necropsy, the liver and pancreas were hard and irregular and the gall bladder was thickened. Histopathological examination showed extensive fibrosis of the pancreas, loss of exocrine acini and marked proliferation of ductules. Numerous cryptosporidia were present on the duct epithelium. The liver of both animals had widespread cirrhosis, bile duct proliferation and cholangitis. Cryptosporidia were found in many bile ducts and on the hyperplastic gall bladder epithelium. Lymph nodes and spleen of both animals showed depletion of cortical and paracortical elements characteristic of advanced immunodeficiency virus infection.

Effects of swab materials and transport media on Aujeszky's disease virus.

The effect of swab materials on the recovery of Aujeszky's disease virus from various transport media held at 4 degrees C was investigated over a five day period. No significant loss in infectivity was found in control preparations, approximately 50 per cent of infectivity was recovered from fluids containing applicator wire and approximately 10 per cent from fluids containing polyester fibre or cotton wool. Virus recovery from fluids containing wooden applicator sticks ranged from no virus recovery in protein free media to from 1 to 10 per cent in protein containing media. Freezing followed by thawing was the most effective of the physical methods used for eluting virus from swab materials.

A selective medium facilitating the isolation and recognition of Bordetella bronchiseptica in pigs.

A medium was developed that in most instances allowed the isolation from pigs of Bordetella (Alcaligenes) bronchiseptica in pure, or virtually pure, culture from such sites as the nasal cavity, which contains many other bacteria. If not suppressed, some of the latter can inhibit, sometimes completely, the growth of the bordetellae on artificial media. Besides being markedly selective, the new medium is simple to prepare, reasonably cheap and practically noninhibitory to B bronchiseptica. This organism produces a distinctive colony that is easily differentiated on morphological grounds from the few other bacteria (such as Alcaligenes faecalis and Pseudomonas spp) which also grow on this medium. Parallel examination of specimens from the nasal cavities of 219 pigs in the field in southern England confirmed that this medium was better than hitherto recommended for the detection of B bronchiseptica. This was particularly true when the organism occurred in small numbers only and/or when bacteria little affected by the inhibitors in the previously recommended media were present in the nasal flora.