Severe chickenpox disease and seroprevalence in Sweden - implications for general vaccination.

OBJECTIVES: To describe the current panorama of severe chickenpox disease and seroprevalence in Sweden, as a basis for the approaching decision on universal vaccination. METHODS: Patients discharged with an International Classification of Diseases 10th revision-code for chickenpox (B01-B01.9) in eight pediatric and infectious diseases departments in Stockholm and Gothenburg in 2012-2014 were included in the study and their medical charts were reviewed. Further, residual serum samples collected from 11 laboratories across Sweden were analyzed for varicella zoster IgG-antibodies to investigate age-specific seroprevalence. RESULTS: A total of 218 children and 46 adults were included in this hospital-based study; 87.2% of children and 63.0% of adults had complications. An underlying condition was not associated with an increased risk of complication. Dehydration (31.7%), bacterial skin infections (29.8%) and neurological involvement (20.6%) were the most frequent complications in children. Among adult cases, 63% were born abroad. The seroepidemiological analysis included 957 patient samples. Seroprevalence was 66.7% at 5 years and 91.5% at 12 years. Infants and adolescents/adults were overrepresented among admitted patients compared to seroprevalence data. CONCLUSIONS: Half of all complications in hospitalized chickenpox cases were seen in previously healthy children, which supports universal childhood vaccination. Adult migrants was a risk group for chickenpox hospitalization. Age-specific seroprevalence was similar to neighboring countries.

Novel major histocompatibility complex class I alleles extracted from two rhesus macaque populations.

We report here the novel Mamu-A and -B alleles that were detected in two groups of rhesus monkeys.

Enhanced cellular immunity and systemic control of SHIV infection by combined parenteral and mucosal administration of a DNA prime MVA boost vaccine regimen.

The immunogenicity and protective efficacy of a DNA and recombinant modified vaccinia Ankara (MVA) vaccine administered by two different routes were investigated. DNA expressing HIV-1 IIIB env, gag, RT, rev, tat and nef, and MVA expressing HIV-1 IIIB nef, tat and rev and simian immunodeficiency virus (SIV) macJ5 gag/pol and vaccinia HIV-1 env, were used as immunogens. Four cynomolgus macaques received DNA intramuscularly (i.m.) at month 0 and intrarectally (i.r.) and intra-orally (i.o.) at 2 months, followed by MVA i.m. at 4 months and i.r. and i.o. at 8 months. Another group of four monkeys received the same immunogens but only i.m. Overall, stronger cellular immune responses measured by ELISPOT and T-cell proliferation assay were detected in the group primed i.m. and boosted mucosally. Following homologous intravenous simian-human immunodeficiency virus (SHIV) challenge, one of eight vaccinated animals was completely protected. This monkey, immunized i.m. and i.r.+i.o., exhibited the highest levels of HIV Env, Nef and Tat antibodies, high HIV Tat cytotoxic T-lymphocyte activity and T-lymphocyte proliferative responses to HIV Env. Four weeks post-challenge none of the monkeys immunized i.m. and i.r.+i.o., and only two out of four animals immunized i.m., demonstrated detectable plasma viral RNA levels. In contrast, all eight control animals had demonstrable plasma viral RNA levels 4 weeks post-challenge. Thus, stronger cellular immune responses and reduction of challenge virus burden were demonstrated in animals immunized i.m. as well as mucosally, compared with animals immunized i.m. only. The breadth and magnitude of the induced immune responses correlated with protective efficacy.

Antimicrobial resistance in staphylococci from canine pyoderma: a prospective study of first-time and recurrent cases in Sweden.

In a prospective study involving eight veterinary clinics during 1995 and 1996, samples from first-time and recurrent cases of canine pyoderma were collected by a needle technique. Three hundred and ninety-four staphylococci were isolated and their susceptibility to various antimicrobial drugs was assessed by a microdilution technique. Resistance to macrolides, lincosamides, fusidic add, tetracycline and streptomycin was significantly more common in isolates from the recurrent cases than from the first-time cases; 20 per cent of the isolates from the first-time cases were resistant to three or more of the antimicrobials tested, compared with 45 per cent of those from the recurrent cases. Coresistance between macrolide-lincosamides, tetracyclines and streptomycin was common. No resistance to penicillinase-stable beta-lactams was observed. A comparison with earlier studies indicated that there had been a marked increase in resistance during the previous five years.

Sows intramammarily inoculated with Escherichia coli influence of time of infection, hormone concentrations and leucocyte numbers on development of disease.

The aim of this study was to identify factors that influence the development of disease in sows inoculated with Escherichia coli in the mammary gland. Ten cross-bred primiparous sows were intramammarily inoculated with living E. coli bacteria at different time points before parturition: seven sows within 48 h before parturition and three sows approximately 96 h before parturition. Before and after inoculation, blood samples and mammary gland biopsy specimens were collected and clinical observations were made. All seven sows inoculated close to parturition developed a rectal temperature of >39.5 degrees C during the first 48 h post-partum and two of them also showed other signs of clinical disease. In the sows inoculated 4 days before parturition, the rectal temperature never exceeded 39.5 degrees C during the first 48 h post-partum and none of them showed any other sign of clinical discase. There was a tendency (P < 0.1) that histological signs of mastitis were more frequent in the sows inoculated close to parturition. There were no overall differences between the two groups of sows in plasma concentrations of cortisol, oestradiol-17beta and 15-ketodihydro-PGF2alpha before inoculation. Before inoculation, the number of neutrophils in the blood was overall higher (P < 0.05) in the group of sows that were inoculated close to parturition. In comparison, the number of lymphocytes before inoculation had a tendency (P < 0.1) to be lower in that group. The data suggest that the time of infection of the mammary gland relative to parturition and the number of circulating neutrophils at the time of infection influence the development of chinical coliform mastitis in the sow.

Induction of immune responses and break of tolerance by DNA against the HIV-1 coreceptor CCR5 but no protection from SIVsm challenge.

An inactivating mutation in the human CCR5 gene reduces the risk of HIV-1 infection in individuals with homozygous alleles. We explored whether genetic immunization would induce an immune response directed to CCR5 structures and if immunological tolerance toward endogenous CCR5 could be broken. We also studied whether this immunization approach could protect cynomolgus monkeys from an infection, with SIVsm, which primarily uses CCR5 as a coreceptor. Epidermal but not intramuscular delivery of the CCR5 gene to mice elicited strong IgG antibody binding responses to CCR5. Intramucosal immunization of cynomolgus macaques with CCR5 DNA followed by boosts with CCR5 peptides induced prominent IgG and IgA antibody responses in serum and vaginal washings. The CCR5-specific antibodies neutralized the infectivity of primary human R5 HIV-1 strains, and the macaque SIVsm but not that of a tissue culture-adapted X4 HIV-1 strain. The consecutive CCR5 gene and CCR5 peptide immunizations induced B- and T-cell responses to peptides representing both human and macaque amino acid sequences of the respective CCR5 proteins. This indicates that tolerance was broken against endogenous macaque CCR5, which has a 98% homology to the human CCR5 gene. After the final boost, the vaccinated monkeys together with two control monkeys were challenged with SIVsm. Neither protection against nor enhancement of SIVsm infection was achieved.

Identification of Escherichia coli recovered from milk of sows with coliform mastitis by random amplified polymorphic DNA (RAPD) using standardized reagents.

A standardized-reagents commercial kit for random amplified polymorphic DNA (RAPD) analysis was used for typing 58 Escherichia coli strains that were recovered from the milk of sows, having coliform mastitis, within a single swineherd in Sweden. Previously, the 58 E. coli strains were characterized serologically and profiled biochemically. They were also evaluated for their serum resistance and their ability to adhere to fibronectin and bovine fetal fibroblasts. The RAPD analysis was fast, easily performed, and required only a nanogram of DNA. The indistinguishable banding patterns obtained with repeated analyses of 2 isolates from each strain demonstrated that RAPD analysis using standardized beads is a technique that provides reproducible results for typing E. coli strains that cause mastitis in sows. The results of the RAPD analyses demonstrated that E. coli sow mastitis strains are highly variable in serotype, biochemical profiles, virulence factors, and RAPD type, and that all 58 strains can be differentiated by means of the RAPD technique. The strains grouped into 24 RAPD types by combining the results of 2 primers, and into 38 groups by combining the results of serotype and RAPD type. No relationship between serotypes, virulence factors and RAPD types was found.

Experimental infections with Actinobacillus pleuropneumoniae in pigs--I. Comparison of five different parenteral antibiotic treatments.

SPF pigs aged 10 weeks were infected intranasally with Actinobacillus pleuropneumoniae serotype 2. After the onset of clinical symptoms of respiratory disease, which occurred 20 h post-infection, parenteral treatment with ceftiofur, danofloxacin, enrofloxacin, penicillin or tiamulin was initiated (n = 8 per group). Untreated groups, of which one was infected, served as controls. The uninfected control group did not show any signs of disease, while the infected control group was severely affected by the infection and also expressed a decreased weight gain following the challenge. Based on clinical signs, the magnitude of pathological lesions in the respiratory tract found at necropsy performed 17 days post-infection and the number of reisolates of A. pleuropneumoniae made at necropsy, treatments with the quinolones (danofloxacin and enrofloxacin) and the cephalosporine (ceftiofur) were superior to those with penicillin and tiamulin. The latter groups also developed antibodies to A. pleuropneumoniae to a larger extent. Some of the pigs treated with ceftiofur and danofloxacin developed antibodies to A. pleuropneumoniae, and the microbe was reisolated from approximately 50% of these animals. In contrast, pigs treated with enrofloxacin did not develop antibodies to A. pleuropneumoniae, and the challenge strain was not found at necropsy. The performance with respect to daily weight gain and feed conversion corresponded well with the clinical signs developed and the findings made at necropsy. The decreased growth recorded during the acute phase of the disease was, to a large extent, caused by a reduced feed intake.

Experimental infections with Actinobacillus pleuropneumoniae in pigs--II. Comparison of antibiotics for oral strategic treatment.

The present study was aimed at scrutinizing the efficacy of oral antimicrobial treatments at experimental challenge using a strain of Actinobacillus pleuropneumoniae serotype 2 known to cause severe disease. SPF pigs aged 10 weeks were infected intranasally and the antimicrobial treatments were initiated 5 h prior to that exposure. Several antimicrobial drugs, as well as the length of the treatment period, were elucidated. The outcome of the challenge was monitored by registration of clinical symptoms, weight gains and the development of serum antibodies to A. pleuropneumoniae. At necropsy, the magnitude of pathological lesions in the respiratory tract and the rate of reisolation of the infective strain were recorded. Animals that became diseased displayed a decreased growth rate caused, to a large extent, by a reduced feed intake. The performance with respect to daily weight gain and feed conversion corresponded well with the clinical signs developed and serologic reactions, as well as with the findings made at necropsy. The results obtained among pigs treated with enrofloxacin, but also with florfenicol or chlortetracycline, were superior to those of pigs treated with penicillin, tiamulin or tilmicosin. A positive effect was obtained using a strategic in-feed medication against infection with A. pleuropneumoniae. Provided that the drug used is effective against the target microbe, initiating treatment prior to infection appeared to be more important than the length of the treatment. It should, however, be remembered that A. pleuropneumoniae was reisolated from all but one medicated group following an experimental challenge given after initiating the medication. Consequently medical treatment as described did not eradicate the microbe.

Primary human immunodeficiency virus type 2 (HIV-2) isolates, like HIV-1 isolates, frequently use CCR5 but show promiscuity in coreceptor usage.

Coreceptor usage of primary human immunodeficiency virus type 1 (HIV-1) isolates varies according to biological phenotype. The chemokine receptors CCR5 and CXCR4 are the major coreceptors that, together with CD4, govern HIV-1 entry into cells. Since CXCR4 usage determines the biological phenotype for HIV-1 isolates and is more frequent in patients with immunodeficiency, it may serve as a marker for viral virulence. This possibility prompted us to study coreceptor usage by HIV-2, known to be less pathogenic than HIV-1. We tested 11 primary HIV-2 isolates for coreceptor usage in human cell lines: U87 glioma cells, stably expressing CD4 and the chemokine receptor CCR1, CCR2b, CCR3, CCR5, or CXCR4, and GHOST(3) osteosarcoma cells, coexpressing CD4 and CCR5, CXCR4, or the orphan receptor Bonzo or BOB. The indicator cells were infected by cocultivation with virus-producing peripheral blood mononuclear cells and by cell-free virus. Our results show that 10 of 11 HIV-2 isolates were able to efficiently use CCR5. In contrast, only two isolates, both from patients with advanced disease, used CXCR4 efficiently. These two isolates also promptly induced syncytia in MT-2 cells, a pattern described for HIV-1 isolates that use CXCR4. Unlike HIV-1, many of the HIV-2 isolates were promiscuous in their coreceptor usage in that they were able to use, apart from CCR5, one or more of the CCR1, CCR2b, CCR3, and BOB coreceptors. Another difference between HIV-1 and HIV-2 was that the ability to replicate in MT-2 cells appeared to be a general property of HIV-2 isolates. Based on BOB mRNA expression in MT-2 cells and the ability of our panel of HIV-2 isolates to use BOB, we suggest that HIV-2 can use BOB when entering MT-2 cells. The results indicate no obvious link between viral virulence and the ability to use a multitude of coreceptors.

Fine characterization of a V3-region neutralizing epitope in human immunodeficiency virus type 2.

We have previously identified two distinct antigenic sites in the third variable region (V3) of human immunodeficiency virus type 2 (HIV-2) corresponding to the principal neutralizing determinant (PND) of HIV-1, the conserved Phe-His-Ser-Gln and Trp-Cys-Arg motifs (positions 315-318 and 329-331), which possibly interact to form a discontinuous antigenic site. The aim of this study was to further identify and characterize the immunogenic sites in the V3-loop of HIV-2 that are important in the binding of neutralizing antibodies and to study in detail the importance of different configurations of peptides corresponding to this region. Peptides representing modifications of the V3-region of HIV-2(SBL6669-ISY) were used for immunization of guinea pigs. With one exception, both the Phe-His-Ser-Gln and the Trp-Cys-Arg motifs were required in the peptide sequences to obtain neutralizing hyperimmune guinea pig sera, and the highest titers were obtained after immunization with 20-27 amino acids (aa) long peptides. Neither substitutions nor deletions of residues between the two motifs, nor the addition of peptide sequences representing a T-helper epitope improved the induction of neutralizing antibodies. Computer simulation modeling revealed that the Phe-315, His-316, Trp-329 and Cys-330 are likely to participate in the formation of a discontinuous epitope. Taken together, these data support the hypothesis that the well conserved motifs FHSQ (positions 315-318) and WCR (positions 329-331) of the HIV-2(SBL6669) V3 region are important targets for neutralizing antibodies, and this may have implications for the design of a future HIV-2 vaccine.

Virulence determinants of Escherichia coli isolated from milk of sows with coliform mastitis.

Escherichia coli isolates recovered from the milk of sows with coliform mastitis were examined to determine their biochemical and serologic characteristics, serum resistance and ability to adhere to fibronectin and bovine fetal fibroblasts. No common biotype was identified, and a variety of serovars were detected. Ninety-five per cent of the investigated strains were serum resistant in swine serum. Binding to fibronectin was demonstrated in most of the strains. At a binding level above 13% of the added fibronectin the strains also adhered to fibroblasts. The results of the study indicate a galactogenous route of infection. The importance of the identified virulence factors need to further elucidated.

A long-term study on the health status and performance of sows on different feed allowances during late pregnancy. II. The total cell content and its percentage of polymorphonuclear leucocytes in pathogen-free colostrum and milk collected from clinically healthy sows.

The main objective of this study was to determine the total cell content, TCC, and the percentage of polymorphonuclear leucocytes, PMNLs, in colostrum and milk collected from sows during the first 22 days of lactation. The pH-values during the same sampling period were also determined. It should be emphasized that all the values obtained emanate from bacteriologically negative colostrum and milk. The potential influence of different levels of late gestation feeding regimes was also evaluated. The TCC-values obtained from milk samples during the first 3 weeks of lactation and exceeding the designated threshold of 10 x 10(6) cells/ml varied between 4% and 21%. Within the TCC-limitation of 10-19.99 x 10(6) cells/ml neither the preceding nor the succeeding cell counts exceeded the threshold in 26.8%. TCC-values above 19.99 x 10(6) cells/ml were preceded and succeeded by cell counts below the threshold in 58.8% and 58.8%, respectively. The TCC-levels below the threshold of 10 x 10(6) cells/ml, expressed as geometric least square means, increased significantly from day 1 to day 3 (1.23 x 10(6) cells/ml versus 1.86 x 10(6) cells/ml) and decreased thereafter gradually to day 22 (1.38 x 10(6) cells/ml). When all values were included, the TCC-values increased in a similar pattern from day 1 to day 3 (1.38 x 10(6) cells/ml versus 3.18 x 10(6) cells/ml). The value on day 22 of lactation was still on a significantly elevated level compared with that of day 1 (2.10 x 10(6) cells/ml versus 1.38 x 10(6) cells/ml). The 2 different feeding regimes were not found to influence the TCC-values during the first 22 days of lactation. In the whole material the PMNL-values, expressed as percentages of the TCC, declined from approximately 60% on day 1 of lactation to between 40% and 50% for the remaining sampling period. This decline was comparable with the one seen in the cell class below the threshold of 10 x 10(6) cells/ml. In the 2 cell classes above 9.99 x 10(6) cells/ml, 78.0% and 88.8% of PMNLs on day 1 declined to about 40% on day 22. This might indicate an inflammatory response on day 1 but without any detectable bacteriological growth. The increase in lactation number, if lactation 1 was compared with the following lactations, revealed a significant rise (p < 0.05) in TCC-level and percentage level of PMNLs. A stepwise and significant increase in pH-level occurred between days 1, 3 and 8 (6.18, 6.56, 7.03) followed by a significant decrease to day 22 (6.91) when pH-values from milk of all cell classes were included.

A long-term study on the health status and performance of sows on different feed allowances during late pregnancy. III. Escherichia coli and other bacteria, total cell content, polymorphonuclear leucocytes and pH in colostrum and milk during the first 3 weeks of lactation.

The objectives of this study were to (1) estimate the clinical status of the mammary glands and (2) compare it with the bacteriological findings, the total cell content (TCC) and its percentage of polymorphonuclear leucocytes (PMNLs) and pH in colostrum and milk secretion of sows on 2 different feeding regimes, high versus low, during late pregnancy. The milk samples were collected from both agalactia post partum (APP) sows and clinically healthy sows. Sows with a rectal temperature exceeding 39.5 degrees C within 48 h after parturition were considered to be diseased in APP and treated medically. The sows were sampled on days 1, 3, 8 and 22 of lactation during 6 consecutive lactations. Irrespective of feeding regimes, 49 out of 77 lactations among the APP sows and 15 out of 96 lactations among the clinically healthy sows revealed E. coli in pure cultures with a concomitant TCC exceeding 10 x 10(6) cell/ml already on the first day of lactation. The healthy sows with E. coli infection were denominated as being subclinically infected sows. The intensity in growth of E. coli successively declined, and the bacteria were finally eliminated between days 3 and 8 of lactation. The TCC were 82 x 10(6) cells/ml and 157 x 10(6) cells/ml in the clinically and subclinically E. coli infected glands, respectively, on the first day of sampling. The TCC declined gradually in both groups of sows, but was still higher than in bacteriologically negative milk on day 22 of lactation. The percentages of PMNLs were 66% and 79% in clinically and subclinically infected glands, respectively, on day 1 of lactation, thereafter decreasing to approximately 50% on day 22 of lactation in both groups of sows. In APP sows, swelling, reddening and/or soreness were registered in 38 out of 87 mammary glands with E. coli mastitis on the first sampling occasion. The TCC in bacteriologically negative colostrum and milk collected from APP sows on day 1 of lactation was significantly higher, 2.27 x 10(6) cells/ml, when compared with the TCC in bacteriologically negative milk secretion from the clinically healthy or subclinically infected sows, 1.38 x 10(6) cells/ml versus 1.51 x 10(6) cells/ml, respectively. The PMNLs were higher on day 1 in clinically healthy sows, 59.6%, than in subclinically infected and APP sows (43.5% and 48.3% respectively). The pH in secretion from clinically or subclinically E. coli infected glands (6.57 versus 6.46) were higher than in bacteriologically negative colostrum samples (6.29) from clinically diseased sows on the first day of sampling. On day 22 of lactation, pH-values had stabilized on a level of approximately 7.00 in all milk samples from earlier bacteriologically positive or negative mammary glands. The 2 feeding regimes, low versus high, were not found to influence TCC, PMNLs or pH except for TCC in bacteriologically negative samples of APP sows (2.69 versus 3.62). The lactation number influenced the PMNLs in both groups of sows with E. coli infected mammary glands, and both the TCC and PMNLs in bacteriologically negative colostrum and milk.

Absolute measures of image quality for the Sens-A-Ray direct digital intraoral radiography system.

To study the noise characteristics of the Sens-A-Ray (Regam Medical Systems AB, Sundsvall, Sweden) system, 20 radiographs were obtained at each of three different exposure levels at 70 and 90 kVp with a homogeneous x-ray field. Exposures were measured with an ionization chamber. Noise power spectra were calculated over three areas within each radiograph, and ensemble averages were subsequently found from 60 data files at each exposure level. Noise equivalent quanta were calculated with the noise power spectra and modulation transfer function data from previous studies. Finally, the detective quantum efficiency was calculated by dividing the noise equivalent quanta by the estimated incident photon fluence at the different exposures. The system has a maximum detective quantum efficiency of approximately 0.030 at 70 kVp and 0.025 at 90 kVp. A broad maximum exists at approximately 2 cycles/mm, indicating that the signal-to-noise ratio is most favorable at this spatial frequency.

Development and characterization of a new model of hematogenous osteomyelitis in the rat.

Hematogenous osteomyelitis was produced in the tibia or the mandible of rats by drilling a hole into the bone, injecting sodium morrhuate, and inoculating Staphylococcus aureus Phillips into the femoral vein. Animals were sacrificed after 2 weeks and examined. The infection was characterized grossly and radiographically by bone deformation, histopathologically by a characteristic suppurative reaction, and microbiologically by the recovery of S. aureus Phillips from the infected tissue. These findings indicate that the model mimics human osteomyelitis with respect to its inflammatory bone changes. In contrast to earlier rat models in which bacteria were injected directly into the bone, this new experimental model allows study of the initiating events of osteomyelitis such as bacterial attachment and might assist as a model for both prophylactic and therapeutic trials.

Color coding of radiographic changes over time by means of image addition.

Differences between sequential radiographs may be displayed in color if the individual radiographs are transformed into monochromatic images and then added. Information in regions where the radiographs are identical is retained whereas differences are emphasized by the color coding that comes about in a quantitative manner from the gray level values in the sequence of radiographs. By using the three additive primary colors, red, blue, and green, two or three radiographs from a sequence may be added. Every possible state of a bone disease, progression, regression, or any combination, will produce a different and specific color code. Different development cycles are described, and the color coding that appears when color image addition is performed is analyzed. The color addition technique should constitute a useful substitute or alternative to subtraction.

Resolution as defined by line spread and modulation transfer functions for four digital intraoral radiographic systems.

Line spread functions for four commercially available systems for direct digital intraoral radiography were determined from images of a slit of negligible width. From the fitted line spread functions presampling modulation transfer functions were calculated. The four systems were the Sens-A-Ray (Regam Medical System AB, Sundsvall, Sweden), the VIXA/Visualix (Gendex, Chicago Ill.), the RVG (Trophy Radiologic, Paris, France), and the Flash Dent (Villa Sistemi Medicale srd, Buccinasco, Italy). Digital intraoral radiography is in a state of rapid development, and detectors as well as computer hardware and software are continually modified and improved resulting in successively changing system parameters. As this occurs the present work provides a method that may be used to determine comparable data on future systems.

Basic technical properties of a system for direct acquisition of digital intraoral radiographs.

The Sens-A-Ray system for direct digital intraoral radiography may be used with any computer compatible with an IBM PC/AT. The system relies on a charge-coupled device designed for direct conversion of x-ray energy to an electronic signal. It is the first such device for direct acquisition of radiographs. Technical properties of charge-coupled device detectors when exposed to radiation energies in the range of x-rays used in dental radiography have been studied. Even in the absence of light or x-radiation there is a spontaneous generation of charge within a charge-coupled device detector that gives rise to a background signal, a dark current. It was found that the dark current is a linear function of exposure time. The dose response of the charge-coupled device detector was determined at nominal kilovoltages that range from 50 to 90 kVp. The dose response was shown to be a linear function of exposure. The functions for all kVp settings were practically identical. The charge-coupled device detector is more sensitive to x-radiation than conventional dental films and, consequently, its exposure range is more narrow. The signal-to-noise ratio was calculated from the digital radiographs used for the dose response test. The ratio is above 10 for exposures higher than about 2 microC/kg. The line spread function was determined from test radiographs of a 10 microns wide slit in a test object of 1.5 mm thick tantalum. After curve fitting, the line spread function could be expressed as the sum of a Gaussian and an exponential function. Presampling modulation transfer functions valid at the detector plane and at an object plane were calculated from fitted data on the line spread function. It is concluded that the Sens-A-Ray system has such technical properties that it may replace conventional film-based systems.