Pyrazolone-type compounds: synthesis and in silico assessment of antiviral potential against key viral proteins of SARS-CoV-2

Coronavirus outbreak is still a major public health concern. The high mutation ability of SARS-CoV-2 periodically delivers more transmissible and dangerous variants. Hence, the necessity for an efficient and inexpensive antiviral agent is urgent. In this work, pyrazolone-type compounds were synthesised, characterised using spectroscopic methods and theoretical tools, and evaluated in silico against proteins of SARS-CoV-2 responsible for host cell entry and reproduction processes, i.e., spike protein (S), M^pro, and PL_pro. Five of twenty compounds are newly synthesised. In addition, the crystal structure of a pyrazolone derivative bearing a vanillin moiety is determined. The obtained in silico results indicate a more favourable binding affinity of pyrazolone analogues towards M^pro, and PL_pro in comparison to drugs lopinavir, remdesivir, chloroquine, and favipiravir, while in the case of S protein only lopinavir exerted higher binding affinity. Also, the investigations were performed on ACE2 and the spike RBD-ACE2 complex. The obtained results for these proteins suggest that selected compounds could express antiviral properties by blocking the binding to the host cell and viral spreading, also. Moreover, several derivatives expressed multitarget antiviral action, blocking both binding and reproduction processes. Additionally, in silico ADME/T calculations predicted favourable features of the synthesised compounds, i.e., drug-likeness, oral bioavailability, as well as good pharmacokinetic parameters related to absorption, metabolism, and toxicity. The obtained results imply the great potential of synthesised pyrazolones as multitarget agents against SARS-CoV-2 and represent a valuable background for further in vitro investigations.

Coronavirus outbreak is still a major public health concern.

Pyrazole Derivatives of Medically Relevant Phenolic Acids: Insight into Antioxidative and Anti-LOX Activity

BACKGROUND

From the point of view of medicinal chemistry, compounds containing phenolic and pyrazolic moiety are significant since they are often constituents of bioactive compounds.

OBJECTIVE

The aims of this study were to synthesize pyrazole derivatives of medically relevant phenolic acids, confirm their structure, and evaluate their antioxidative and anti-LOX activities.

METHODS

Phenolic pyrazole derivatives were obtained, starting from esters of medically relevant phenolic acids. The structures of all obtained compounds were determined by NMR and IR spectroscopy, and UV-Vis spectrophotometry. In addition, the single-crystal X-ray diffraction was used. Pyrazole derivatives were tested for their in vitro antioxidative (DPPH assay), and lipoxygenase (LOX) inhibitory activities. Radical quenching mechanism was estimated using DFT and thermodynamic approach, while molecular docking was used to estimate the binding mode within the enzyme.

RESULTS

Pyrazole derivatives were obtained in high yields. The crystal structure of a new compound 3e was determined. Pyrazole derivative with catechol moiety 3d exhibited excellent radical scavenging activity, while compound 3b exhibited the best anti-LOX activity. Molecular docking study revealed that there is no direct interaction of any ligand with the active site of LOX-Ib, but pyrazoles 3a-e behave as inhibitors blocking the approach of linoleic acid to the active site.

CONCLUSION

In this research, protocatechuic and vanillic acid pyrazole derivatives have been obtained for the first time. In vitro antioxidative assay suggests that pyrazole derivate of protocatechuic acid is a powerful radical scavenger, while anti-LOX assay indicates a pyrazole derivative with 4-hydroxyphenyl moiety.

Geographical distribution of Slovenian BRCA1/2 families according to family origin: implications for genetic screening

Knowledge of the geographical distribution of highly recurrent mutations may be useful for efficient screening in cancer families. Since the cloning of the BRCA1/2 genes, it is known that the wide spectrum of deleterious mutations shows high ethnic and geographic heterogeneity. In this study, we have tested probands from 582 breast/ovarian cancer families and positioned all 156 BRCA1/2 families on the map according to the family origin. We observed that high-risk families with the same recurrent mutation present a typical geographical distribution and that different recurrent mutations may show different distribution patterns. We then evaluated the genetic screening implications of this heterogeneous prevalence of the most recurrent mutations found [300T>G(c.181T>G), 1806C>T(c.1687C>T), 969ins7(c.844_850dupTCATTAC), 5382insC(c.5266dupC), 235G>A(c.116G>A) in BRCA1 and IVS16-2A>G(c.7806-2A>G) in BRCA2]. On the basis of these results, specific testing procedures for new incident cases may be offered according to their family origins and, according to the information regarding clusters revealed in this study, the individuals (especially those at low risk), originating from regions with clusters, might be screened preferentially for cluster mutations and analysis may be simplified according to the family origin.

Specific T cell responses to Helicobacter pylori predict successful eradication therapy

OBJECTIVE

The aim of our prospective study was to test a specific T cell response to Helicobacter pylori before therapy and compare it to the success of H. pylori eradication 12 months later.

METHODS

A total of 14 dyspeptic patients and 10 patients with previous H. pylori eradication failure were recruited into the study; before therapy their gastric samples for H. pylori cultivation and blood samples for dendritic cell cultivation were obtained. H. pylori antigens were produced to prime dendritic cells for stimulation of T lymphocyte response.

RESULTS

The level of cytokine response by T cells was measured and results were compared with the success of H. pylori eradication one year later. There was a significantly increased response in expression of IFN-gamma and IL-4 molecules by DCs stimulated T cells in subjects that successfully eradicated H. pylori compared with those who failed to eradicate the infection. Our results support the hypothesis that successful H. pylori eradication requires established anti-H. pylori immune response besides antibiotic treatment.

CONCLUSION

Effective IFN-gamma cytokine response to H. pylori antigens seems to be of particular importance. Immunisation could be therefore beneficial for H. pylori eradication, while immunodeficiency could cause the failure in H. pylori eradication.

The immunohistochemical and serological determination of p53 protein in patients with malignant lymphomas

The product of mutated p53 gene is a protein with abnormal conformation, impaired DNA binding, and a prolonged half life, the latter of which results in immunohistochemically detectable levels within nuclei of malignant cells. The present study was aimed at the immunohistochemical determination of p53 overexpression in patients with various histological types of nonHodgkin's lymphomas (NHL), with a particular interest in gastric lymphomas. In these patients, as well as in controls, also serological determinations of p53 protein were performed using an ELISA method. Immunohistochemical overexpression of p53 protein was found in 21% of NHL patients, with the highest incidence of p53 immunoreactivity in cases of Burkitt's lymphoma, follicle center lymphoma grade III, and diffuse large B-cell lymphoma. In gastric lymphomas the overall incidence of p53 immunoreactivity was as high as 46%. Serological ELISA determinations of p53 protein in NHL patients and in controls remained below the lowest detection limit of the method in all 128 cases. Considering that p53 mutations are associated with poor response to therapy, and consequently with poor prognosis, it is of great importance to determine the subset of patients that are particularly at risk for an unfavorable outcome and should be treated more aggressively. Immunohistochemical determinations of p53 overexpression represent a rapid and simple, yet somewhat imperfect technique for an estimation of the frequency of mutational events. On the other hand, serological determinations of p53 protein are completely inadequate for the evaluation of p53 status.

Soluble tumor necrosis factor receptor I (sTNFRI) as a prognostic factor in melanoma patients in Slovene population

Tumor necrosis factor alpha (TNF-alpha) and its receptors (TNFRI and TNFRII) which exist in soluble form as a product of cleavage of the extracellular domain of membrane integrated receptors, still rise debate about their importance. It was reported that TNF-alpha has numerous actions in diseases such as inflammation, autoimmunity, infectious diseases, septic shock and many types of cancer [1, 2]. Several authors have reported the significance of sTNFRI level in serum of cancer patients [3, 4]. This study was performed in collaboration with the Institute of Oncology of Slovenia. At least two different mouse monoclonal antibodies (MAbs) against human sTNFRI have been prepared to obtain a sensitive and reliable sandwich ELISA. It was compared with commercially available R&D and Endogen ELISAs for the determination of sTNFRI. Groups of patients with different stages of melanoma and epithelial ovarian carcinoma were tested and their clinical records were reexamined. Levels of sTNFRI were measured and compared with the normal serum levels of sTNFRI.

Construction of an expression cassette with hTNF-alpha gene for transient expression of the gene in mammalian cells

BACKGROUND

Tumor vaccines, which are created by the insertion of cDNA encoding different cytokines into the tumor cells, are capable of inducing a very complex immune reaction including activation of CD8 T cells, granulocytes, macrophages, the triggering of cytokine cascades and antibody production. Aiming to create genetically modified tumor cells which could produce and secrete Human Tumor Necrosis Factor-alpha (hTNF-alpha), we constructed the expression cassette containing hTNF-alpha gene in pcDNA3 plasmid vector.

MATERIALS AND METHODS

The successful ligation of cDNA encoding for hTNF-alpha into pcDNA3 plasmid vector was confirmed by PCR, restriction mapping and sequence determination. The constructed expression cassette in pcDNA3 vector was than transferred in vitro into malignant melanoma B16 tumor cells by the method of Receptor Mediated Gene Transfer (RMGT).

RESULTS

Measurable amounts of hTNF-alpha protein detected in the medium of transfected cells proved that tumor cells modified in this manner became producers of hTNF-alpha protein.

CONCLUSION

The expression of the transferred gene was transient and the produced protein was biologically active. Furthermore, the production of hTNF-alpha protein was also observed in sub-lethally irradiated tumor cells, showing that the expression cassette was preserved during the irradiation and that the cells were potentially applicable as a tumor vaccine.

Transfection of mammalian cells by the methods of receptor mediated gene transfer and particle bombardment

The efficacy of currently developed methods for gene transfer into mammalian cells depends primarily on the transfection technique, and also on the type of targeted cells. Considering the importance of gene transfer in the creation of gene therapies, our study was aimed at the assessment of transfection capacity of receptor mediated gene transfer method (RMGT), and method of particle bombardment (helios gene gun system--HGG) in different normal and malignant mammalian cells ex vivo. In addition, the HGG was also assessed for its ability to transfect tumor cells of subcutaneous (s.c.) tumors in C57Bl/6 mice in vivo. Using RMGT an average ex vivo transfection rate of 35.7%, and 20.4% was achieved in malignant melanoma B-16, and human breast adenocarcinoma MCF7, respectively. However, in normal fibroblast L929 cells the transfection by RMGT succeeded only in 2.1% of the cells. On the other hand, the transfection efficacy of HGG was comparable in both malignant cell lines resulting in an average gene transfer to 9.6% of B-16 and 10.5% of MCF7 cells, while only 3.9% of normal fibroblasts were successfully transfected. Application of HGG for an in vivo gene transfer into s.c. B-16 melanoma tumors in C57Bl/6 mice resulted in a successful but limited transfection of the epithelium as well as of the superficially sited tumor cells. Taking into consideration both methods, RMGT is more appropriate for ex vivo transfection of cells, under the condition that target cells express a specific receptor for the molecule attached to the carrier. On the other hand, HGG is not complicated to use, no requirements for specific structures on target cells are necessary (potentially usable in different cells), and it has applicability in direct in vivo transfection processes.

Effectiveness of a simply designed tumor vaccine in prevention of malignant melanoma development

We investigated the efficacy of a simple syngeneic tumor vaccine to induce specific antitumor immunity in female C57Bl/6 mice. Tumor vaccine was prepared by mixing irradiated B-16 melanoma tumor cells with the pleiotropic biological response modifier-maleic anhydride divinyl ether (MVE-2). Experimental animals were pretreated with the vaccine in order to prevent the development of intraperitoneal (i.p.) B-16 melanoma tumors after inoculation of viable tumor cells. More than 40% of prevaccinated animals challenged i.p. with 5 x 10(5) viable tumor cells were completely protected from tumor development and remained tumor-free 100 days after tumor cell inoculation. The percentage of tumor-free animals (survivors) rose to as much as 90% when the application of tumor vaccine was repeated two weeks after the first vaccination (i.e. one week after the inoculation of viable tumor cells). The induced antitumor response depended predominantly upon macrophage function, since vaccinated animals which were depleted of peritoneal macrophages died within the same time range as animals in the control group. Also, tumor-type specificity of the vaccine was confirmed by the fact that the animals vaccinated with B-16 melanoma vaccine were not protected from the development of another type of tumor. In conclusion, comparison of the experimental data with the data from the literature suggests that our simple tumor vaccine may be as effective as genetically engineered tumor vaccines. At the same time, this kind of vaccine is easier to control and thus safer to apply in humans when compared to genetically engineered vaccines.

New TNF-alpha analogues: a powerful but less toxic biological tool against tumours

Our approach to the modification of recombinant human tumour necrosis factor alpha (rhTNF-alpha) comprised changes in flexible loop regions on the surface of the TNF molecule. Using this approach, two different rhTNF-alpha analogues LK 801 and LK 805 were synthesized and tested for their ability to affect the growth of Sa-1 tumour cells. Results obtained in vitro indicate that neither rhTNF-alpha nor its analogues have a direct cytotoxic effect. In vivo experiments were performed on subcutaneous Sa-1 tumours in A/J mice, where the antitumour effect and the toxic side effects of the cytokines were followed. There was no significant difference between growth delay of tumours in animals treated with native rhTNF-alpha and in animals treated with one of the analogues. On the contrary, the LD50 for rhTNF-alpha was 29.1 microg, for LK 801 59.3 microg, and for LK 805 even 66.1 microg, indicating that LK 801 and especially LK 805 were significantly better tolerated. The results confirm that the rhTNF-alpha molecule has been successfully modified resulting in two new analogues with a potent antitumour activity and much lower systemic toxicity. A particularly low systemic toxicity and a strong antitumour effect were observed after treatment with LK 805 suggesting that this analogue merits further investigation in pre-clinical and clinical trials.

Clinical evaluation of potential usefulness of CEA, CA 15-3, and MCA in follow-up of breast cancer patients

The potential usefulness of MCA, CA 15-3 and CEA in monitoring of breast cancer patients was evaluated in 135 female patients with histologically confirmed breast cancer. The patients were classified into two groups as follows: group of patients with no evidence of disease, NED; and group of patients with progressive disease, PD. In total, 2106 measurements of CEA, CA 15-3, and MCA were performed using an enzyme immunoassay. Serum levels of all three markers in the NED group differed significantly from those of patients with PD. The observed differences in the sensitivity and specificity of CEA, CA 15-3, and MCA tests were not significant. The serum concentrations of a particular marker correlated well with the concentrations of the other two markers, except when CEA was correlated with MCA or CA 15-3 in NED group patients. The elevation of tumor markers preceded by some 7 months the clinical evidence of dissemination, and marker levels reflected at a high percentage the response to therapy in PD patients. Therefore, this clinical study confirmed that MCA, CA 15-3 and also CEA are suited to discriminate between disease and disease-free periods, and also validated the usefulness of markers for treatment response monitoring.

Searching for new TNF-alpha analogs having potential application in cancer therapy

Two new TNF-alpha analogs were prepared and tested for their anti-tumor activity on fibrosarcoma SA-1 tumor model in vivo. In analog LK-801 two histidines (His107His108) were introduced into the surface loop thus enabling efficient purification by metal-affinity chromatography. This analog showed less side effects and can serve as a lead compound to look for other useful mutations. Another analog LK-802 was designed by introduction of additional pair of mutations (Cys95Cys148) into LK-801 in order to prepare disulfide linked TNF trimers. Cytotoxicity on mouse cell line L929 was comparable to TNF-alpha, but effect on tumor growth was quite reduced. Pharmacokinetic study revealed that serum levels of LK-802 were quite low in comparison to native TNF-alpha. This at least partially explains why anti-tumor activity of LK-802 is reduced and also illustrates the problems in designing the analogs with desired in vivo biological properties.

In vitro TNF-alpha production and in vivo alteration of TNF-alpha RNA in mouse peritoneal macrophages after treatment with different bacterial derived agents

Since muramyl dipeptide (MDP) was recognized as a potent monocyte/macrophage activating agent, many MDP analogues were synthesized and tested for their ability to augment the host immune defence system against neoplasms. This study was performed to determine whether the newly synthesized desmuramyl N-acyl dipeptides LK 409 and LK 410 were also capable of affecting the immune system. For this purpose, the peritoneal macrophages were incubated in vitro with these two agents and TNF-alpha production was measured. In addition, the effect of LK 409 and LK 410 on TNF-alpha and IL-1 RNA levels in in vivo stimulated macrophages was determined by quantitative polymerase chain reaction (RT-PCR). None of the LK 409 and LK 410 concentrations tested were able to render macrophages in vitro to excrete a detectable amount of TNF-alpha in the supernatant fluid. However, the TNF-alpha and IL-1 RNA levels in macrophages of in vivo treated mice (C57Bl/6) were increased in comparison to mock-treated mice. The results indicate that LK 409 and LK 410 are capable of inducing an increase in TNF-alpha and IL-1 RNA levels, yet in vitro TNF-alpha production remains under detectable levels (40 U/ml).

Muscarinic receptor function in the guinea-pig uterine artery is not altered during pregnancy

The effects of acetylcholine on isolated uterine artery rings of non-pregnant and pregnant guinea-pigs were investigated. Acetylcholine induced a concentration- and endothelium-dependent relaxation of both types of vessels, with similar pD2 (non-pregnant: pD2 = 7.66; pregnant: pD2 = 7.59) and maximal response values. The pKA values (non-pregnant vs. pregnant) of acetylcholine were 6.17 vs. 6.09. The occupancy response relationship was non-linear since the half-maximal response to acetylcholine (non-pregnant vs. pregnant) was obtained with 2.86 vs. 2.91% receptor occupancy. In quiescent preparations, the muscarinic receptor antagonists, atropine, pirenzepine, N,N'-bis[6-[(2-methoxybenzyl)amino]hexyl]-1,8-octane-diamine tetrahydrochloride (methoctramine) and para-fluoro-hexahydro-sila-difenidol (pFHHSiD), produced parallel rightward shifts of the curves for acetylcholine and the slopes of the Schild plots were not significantly different from unity. The plots constrained to a slope of unity gave the following -log KB values (non-pregnant vs. pregnant): atropine (9.68 vs. 9.75), pirenzepine (6.75 vs. 6.53), methoctramine (6.13 vs. 6.23) and pFHHSiD (7.88 vs. 7.96). It is concluded that, in guinea-pig uterine arteries, acetylcholine induces endothelium-dependent relaxation and acts as a full agonist, regardless of pregnancy status. We suggest that the relaxation induced by acetylcholine, in either non-pregnant or pregnant guinea-pig uterine artery, is mediated via the M3 subtype of muscarinic receptors.

Interactions of interferon and vinblastine on experimental tumor model melanoma B-16 in vitro

In this study, we tried to define in vitro interactions of two antitumor agents that have different sites and different mechanisms of action. Vinblastine (VLB) in combination with human recombinant interferon-alpha A/D (rHuIFN-alpha A/D) and in combination with murine recombinant interferon-gamma (rMuIFN-gamma) was studied. The effect of the combination was determined with cell growth kinetics assay on B-16 melanoma and the interaction defined by means of Spector's formula. Both the combination of rHuIFN-alpha A/D with VLB and the combination of rMuIFN-gamma with VLB synergistically inhibited cell growth in vitro. There was a positive biochemical modulation between the two drugs, but it is still unknown whether it occurred at the level of uptake into the cell, metabolism within the cell or egress from the cell.

[Indicators of hospital treatment and the organization and management of injuries and diseases in armed combat in 1991 and 1992]

Efficiency of organisation of management of the injured and diseased in combat operations in 1991/2 and results of hospital treatment are studied. The questionnaire was established for collection of data about stationary treatment of the wounded and diseased in 7 military and 15 civilian medical institutions. Data about 9.243 injured of whom only 5.57% were civilians are especially analysed. In most cases injuries were inflicted by mine-explosive devices (48.77% in combat and 6.27% in non-combat operations), then those inflicted by bullets (38.58% in combat and 8.02% in non-combat operations). Self-inflicted injuries occurred in 5.79% in combat and 10.32% in non-combat operations. Injuries inflicted in non-combat operations were found in a high percentage (46.60). They mostly occurred in the open air (41.26%). Injuries of extremities are predominant (64.70%), then injuries of the head and neck (17.90%), thorax (9.90%), abdomen and pelvis (7.50%). Young men (20-24 years old) were commonly injured but the older ones (over 40 years) have been also frequently injured (18.30%). Evacuation of the wounded and diseased was performed mainly by ambulances (about 60%) or helicopters (16%), especially to the medical institutions far in the country (to M.M.A. up to 60%). The first aid was given within the first ten minutes after injury in 55.00% and within 30 minutes in 65.58% of cases. Mutual aid was most frequently applied (33.12%) and then first aid given by general practitioners (32.12%). Surgical treatment was provided one hour after injury to every fourth wounded (24.08%) and after six hours to more than one third of the wounded (31.88%).(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of TNF-alpha pharmacokinetics in SA-1 tumor-bearing mice

Fibrosarcoma-SA-I-tumor-bearing mice were treated s.c. in the vicinity of tumors (peri-tumorally) or intravenously, with recombinant human TNF-alpha lacking 1 to 3 amino acids from N-terminal part (TNF-alpha Nv3). Tumor growth delay, observed after both routes of TNF-alpha Nv3 application, was statistically significant, though a better anti-tumor effect was achieved after peri-tumoral application. TNF-alpha Nv3 serum levels were determined in these animals and compared with TNF-alpha Nv3 serum levels in healthy animals, which were treated with TNF-alpha Nv3 either s.c. or i.v. The peak serum levels of TNF-alpha Nv3 applied peri-tumorally/s.c. were significantly higher in tumor-bearing than in healthy mice, whereas smaller differences in peak serum levels were found after i.v. application, which might correlate with anti-tumor activity. Whatever the route of application, TNF-alpha Nv3 elimination from the serum of tumor-bearing mice was slower than that in healthy animals. Also, comparison of TNF-alpha Nv3 pharmacokinetic parameters for tumor-free and sarcoma- or melanoma-bearing mice has demonstrated that the pharmacokinetics of TNF-alpha Nv3 are modified in tumor-bearing animals.

Potentiation of bleomycin antitumor effectiveness by electrotherapy

Electrotherapy was investigated for its ability to increase the responsiveness of murine tumors to bleomycin treatment. Mice bearing fibrosarcoma were treated with 250 micrograms bleomycin and then with 0.6 mA direct current (DC) for 60 min. Antitumor effects of single treatments were moderate with bleomycin, but significant with electrotherapy. Combined treatment with bleomycin followed by electrotherapy was more effective than either treatment alone. Tumor growth delay of the animals after combined treatment was greater than the summation of tumor growth delays after single treatments. The results of our study indicate that bleomycin and electrotherapy treatments interact, with electrotherapy potentiating the effectiveness of bleomycin treatment.

The influence of TNF on the membrane fluidity of tumor cells

Possible TNF (tumor necrosis factor) effects on the membrane fluidity of tumor cells were investigated. Viable tumor cells, TNF sensitive, were obtained from the ascitic form of the SA-1 tumor bearing mice. The influence of in vitro and in vivo treatment of cells with the TNF analog was investigated by EPR (electron paramagnetic resonance). SA-1 cells were spin labeled with the methylester of 5-doxylpalmitate, which primarily dissolves in the membranes. The maximal hyperfine splitting was determined and the empirical correlation time calculated. The results show that TNF significantly decreases the correlation time, i.e. it increases the fluidity of SA-1 cell membranes. Such alteration could contribute to the cytotoxicity of TNF.

Anti-tumor effect of electrotherapy alone or in combination with interleukin-2 in mice with sarcoma and melanoma tumors

Electrotherapy with direct current (DC) was performed on two murine tumor models, fibrosarcoma SA-1 and melanoma B16. Three Pt/Ir cathodes were inserted directly into the subcutaneous tumors and two anodes subcutaneously in the vicinity of the tumor. Significant tumor growth delay was achieved after electrotherapy and was dependent on DC intensity (0.6, 1.0, 1.4 and 1.8 mA). Melanoma B16 tumors were more sensitive to electrotherapy than SA-1 tumors. In order to enhance the antitumor effect of electrotherapy, combined treatment with interleukin-2 (IL-2) was performed. When both therapies were combined significant tumor growth delay and also higher curability rate was achieved. The results imply that electrotherapy can be an effective antitumor therapy and that the effects can be enhanced with additional IL-2 therapy.

Histopathology and immunopathology of skin biopsy specimens in Mediterranean spotted fever

Histology of skin lesions and demonstration in them of Rickettsia conorii by direct immunofluorescence test (DIF) are presented in 13 patients with Mediterranean spotted fever (MSF). The lymphohistiocytic vasculitis which dominated the picture is not specific, however, it could be suggestive for the diagnosis of rickettsiosis. By DIF we demonstrated rickettsial coccobacillary forms in all the patients: in 12 macular lesions and in one "tache noire". The diagnosis was also confirmed by indirect immunofluorescence test in each case. DIF test was shown to be sensitive, specific and reliable in early diagnosis of MSF.

Comparison of serologic methods for the diagnosis of Mediterranean spotted fever

During summer Mediterranean spotted fever (MSF) is prevalent in the subcostal part of Croatia (North Dalmatia) as well as in other areas of the Mediterranean coast. We compared the specificity and sensitivity of complement fixation (CF), latex agglutination (Latex-R. conorii), microimmunofluorescence (micro-IF) and enzyme-linked immuno assay (ELISA) for detection and measuring antibodies against Rickettsia conorii in 78 sera from 46 patients with/or suspected Mediterranean spotted fever. The seroreactivity with SFG antigens containing the Rickettsia conorii-antigen(s) as a common determinant, was positive in all four serological tests suggesting that Rickettsia conorii was the probable causative agent of infection in our patients.