SUPREME-HN: a retrospective biomarker study assessing the prognostic value of PD-L1 expression in patients with recurrent and/or metastatic squamous cell carcinoma of the head and neck

Background

Programmed cell death ligand-1 (PD-L1) expression on tumor cells (TCs) is associated with improved survival in patients with head and neck squamous cell carcinoma (HNSCC) treated with immunotherapy, although its role as a prognostic factor is controversial. This study investigates whether tumoral expression of PD-L1 is a prognostic marker in patients with recurrent and/or metastatic (R/M) HNSCC treated with standard chemotherapy.

Methods

This retrospective, multicenter, noninterventional study assessed PD-L1 expression on archival R/M HNSCC tissue samples using the VENTANA PD-L1 (SP263) Assay. PD-L1 high was defined as PD-L1 staining of ≥ 25% TC, with exploratory scoring at TC ≥ 10% and TC ≥ 50%. The primary objective of this study was to estimate the prognostic value of PD-L1 status in terms of overall survival (OS) in patients with R/M HNSCC.

Results

412 patients (median age, 62.0 years; 79.9% male; 88.2% Caucasian) were included from 19 sites in seven countries. 132 patients (32.0%) had TC ≥ 25% PD-L1 expression; 199 patients (48.3%) and 85 patients (20.6%) had TC ≥ 10% and ≥ 50%, respectively. OS did not differ significantly across PD-L1 expression (at TC ≥ 25% cutoff median OS: 8.2 months vs TC < 25%, 10.1 months, P = 0.55) or the ≥ 10% and ≥ 50% cutoffs (at TC ≥ 10%, median OS: 9.6 months vs TC < 10%, 9.4 months, P = 0.32, and at TC ≥ 50%, median OS 7.9 vs TC < 50%, 10.0 months, P = 0.39, respectively).

Conclusions

PD-L1 expression, assessed using the VENTANA PD-L1 (SP263) Assay, was not prognostic of OS in patients with R/M HNSCC treated with standard of care chemotherapies.

Trial registration ClinicalTrials.gov, NCT02543476. Registered September 4, 2015.

A retrospective cohort study of PD-L1 expression in recurrent and/or metastatic squamous cell carcinoma of the head and neck (SUPREME-HN)

6040

Background: Patients with recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) have a poor prognosis. Targeting the PD-1/PD-L1 axis has resulted in clinically meaningful antitumor activity and improved overall survival (OS) in R/M HNSCC patients. Tumoral PD-L1 expression correlates with response to blocking PD-1/PD-L1 antibodies. We investigated the prognostic value of PD-L1 expression in R/M HNSCC patients. Methods: Archival tumor samples from R/M HNSCC patients diagnosed between March 2011 and June 2015 at 12 institutions in 6 countries were stained for PD-L1 and clinic-demographic data were abstracted from medical records. Tumoral PD-L1 protein expression was assessed with the validated Ventana SP263 assay and scored as high (≥25% of tumor cells [TC]) or low/negative ( < 25% of TC). Extracted data included demographic and tumor characteristics, treatment patterns, and clinical outcomes. Descriptive analyses were conducted and survival estimated by the Kaplan-Meier method. OS was defined from the diagnosis index date of R/M disease to time of death. Results: As ofSeptember 26, 2016 (interim analysis), data were available for 143 patients of whom 138 were eligible for analysis. Median age was 62.0 years (range, 28.0−88.0), 76.8% were male, and 84.0% were white. PD-L1 protein expression was high in 43 patients (31.2%), low/negative in 91 (65.9%), and unknown in 4 (2.9%). Median OS (8.2 vs. 8.8 months; P = 0.94) and progression-free survival (PFS) from the start of first-line (6.0 vs. 5.6 months; P = 0.29) or second-line therapy (7.1 vs. 1.8 months; P = 0.11) did not significantly differ between PD-L1 high and low/negative patients, respectively. There were no significant differences in OS based on PD-L1 status within subgroups defined by age, race, tobacco or alcohol use, primary tumor site, performance status, metastatic disease at diagnosis, or treatment with platinum-based chemotherapy. Conclusions: Interim analyses indicate that PD-L1 status is not associated with OS or PFS in R/M HNSCC patients.

Treatment of fish parasites: 5. The effects of sym. triazinone (Toltrazuril) on fish parasitic ciliophora (Ichthyophthirius multifiliis FOUQUET, 1876, Apiosoma amoebea GRENFELL, 1884, Trichodina sp. EHRENBERG, 1831)

For chemotherapy of fish parasitized by different Ciliophora (Protozoa) toltrazuril was tested in vivo and in vitro against skin and gill parasitizing species (e.g. Ichthyophthirius multifiliis, Apiosoma amoebea and Trichodina sp.). For in vitro treatment naturally infected fish were incubated at 20 °C for 0.3,1,2,4.5 h in water containing 0,1,5,10,20 or 50 μg toltrazuril/ml. Lethal damages already occurred in about one third of the trophozoites of I. multifiliis after incubation in 5 μg/ml for 4.5 h, and in more than two thirds of the trophozoites after incubation in 10 μ/ml for 2 h. A few trophozoites, however, were still able to leave their hosts, to encyst and to produce theronts. However, when treatment was done by intermittent therapy (1×10 μg/ml for 2 h, first day; 1 × 20 μg/ml for 1 h, second day; 1 × 20 μg/ml for 1 h, third day) all the trophozoites were lethally damaged. The damages consisted in the destruction of the outer cell membranes, of the cilia, and of the mitochondria, as well as in the complete abolishment of the ribosomes and in the enlargement of the nuclear space. After in vitro treatment (10 μg/ml, 2 h) all the trophozoites were lethally damaged. In contrast to the trophozoites, the free-swimming theronts of I. multifiliis were not affected by the drug. In vivo treatment starting with 20 μg/ml for 1 h led to severe damages in A. amoebea, which were intensified after treatment with 50 μg/ml for 0.3 h. The specimens were heavily contracted, and the oral cilia were redrawn. Furthermore, the pellicular pores seen in the surface of controls were not detectable. Despite the affections caused by the treatment the parasites did not drop off their hosts. In vivo treatment against Trichodina sp. led to a reduced motility in these parasites starting with 10 μg/ml for 2 h. Incubation with 20 μg/ml for 1 h caused a complete stop of motion in most of the specimens. The highest dose (50 μg/ml; 0.3 h) only caused a dropping off in about one third of the specimens from their hosts. Treated specimens of Trichodina sp. had a more flattened appearance compared to untreated controls, and the epistomial disc was drastically enlarged. From these experiments it is suggested that treatment against the trophozoites of I. multifiliis should be done by intermittent therapy according to the following scheme: 1st day: 10 μg/ml, 2 h, 2nd day: 20 μg/ml, 1 h; 3rd day: 20 μg/ml, 1 h. In the cases of Apiosoma spp. and Trichodina spp. infected fish incubating with 50 μg/ml for only 20 minutes is recommended.

Effects of a combinations of emodepside and praziquantel on parasites of reptiles and rodents

A new combination of two anthelmintic compounds containing emodepside and praziquantel (Profender, Bayer AG, Levekusen, Germany) was tested in pet rodents and reptiles. Topical application of the two compounds led to the quick disappearance of nematodes and cestodes from a broad spectrum of hosts including mice, jirds, snakes, anole lizards, turtles, monitor lizards, etc. In reptiles the dosage had to be increased, since the thick outer layer of the epidermis hinders the penetration of the compounds. In animals with an extremely thick epidermis (e.g. monitor lizards, leguans) the new product was applied under the armpits.

Efficacy of a combination of imidacloprid and moxidectin against parasites of reptiles and rodents: case reports

A new compound containing imidacloprid 10% (w/v) and moxidectin 2.5% (w/v) (Advantage multi, Advocate) was applied as a spot-on treatment to mice experimentally infected with Trichuris muris. Case reports of reptiles found positive for nematode and mite infections following parasitological examination and treated with this compound are also discussed. The results demonstrated that the registered, recommended 2.5% moxidectin concentration for use in dogs was sufficient to eliminate nematodes and mites in reptiles. Infections with nematodes were successfully treated with a single application. Mite infestations in reptiles were eliminated using a treatment repeated on 3 consecutive days.

Experimental quantification of the feline leukaemia virus in the cat flea (Ctenocephalides felis) and its faeces

Cat fleas (Ctenocephalides felis) were fed via artificial membranes and infected with the feline leukaemia virus (FeLV) from cell cultures. After removing the fleas from the blood source, the quantity of virus in the flea and its faeces was measured over a defined period of time. The virus was detectable in the fleas for up to 30 h at room temperature and up to 115 h at 4 degrees C. In the faeces, the amount of virus decreased much more slowly--after 2 weeks half of the initial amount of virus could still be detected. Thus the faeces might be a source of further infections, e.g. for the flea larvae or the cat itself.

Genebank accession numbers of sequences of Culicoides species vectors of bluetongue virus in Germany

The paper offers the genebank accession numbers of Culicoides obsoletus, Culicoides scoticus and Culicoides pulicaris sequences (ITS 1, ITS 2, 18S rRNA) that had been shown to be vectors of the bluetongue virus serotype 8, which was introduced in 2006 into Germany and spread until 2009 all over Central Europe, including parts of England. The numbers are FN 263292 until FN 263323.

Light and transmission electron microscopic studies on trophozoites and cyst-like stages of Histomonas meleagridis from cultures

The present study deals with Berlin strains of Histomonas meleagridis, the specimens of which were cultivated in Dwyer's medium. The light and electron microscopic examination revealed that the cultivated trophozoite stages (reaching about 10 mum in size) appeared more or less spherical, although their surface (covered by a single membrane) showed amoeba-like waves. All stages were uni-nucleated and reproduced by binary fission with an extranuclear spindle apparatus. Some trophozoites appeared ovoid and possessed a single flagellum with a typical microtubular 9 x 2 + 2 arrangement. Furthermore, the latter were characterized by an inner row of typical microtubules (remnant of an axostyle) and a Golgi apparatus (both adjacent to the nucleus), multivesicular structures, hydrogenosomes, and many food vacuoles containing either starch grains or bacteria. Their cytoplasm was densely filled with glycogen granules and ribosomes. Similar stages were also documented in the caeca and cloaca of chicken when being inoculated (via cloaca) with such culture stages. In addition to these typical trophozoites, the cultures contained a low number of 10-mum-sized spherical cyst-like stages with a surrounding amorphous layer. The cytoplasm of some of these cyst-like stages-when studied by electron microscopy-appeared with two membranes or had formed an amorphic, cyst-wall-like layer at their surface, apparently corresponding to their light microscopical appearance. Such stages might be involved in transmission from one host to another and probably have been missed before in microscopical examinations of infected poultry.

Investigations on the life cycle and morphology of Tunga penetrans in Brazil

In the present study, the life cycle of Tunga penetrans was established in Wistar rats in the laboratory, and the morphology of the resulting developmental stages was studied by means of light and scanning electron microscopy. It was seen that the females enter at a nonfertilized stage through the skin of their hosts. Only there the copulation occurs, while females and males brought together in a Petri dish showed no interest in each other. In any way -- fertilized or not -- the females start about 6 days after penetration and hypertrophy with the ejection of eggs. While fertilized eggs proceed to development, the unfertilized ones remain arrested. The eggs are ovoid and measure about 600 x 320 mum. The larvae hatch from the eggs 1-6 days (mean 3-4) after ejection. Formation of larvae 2 took at least another day, while 4 up to 10 days more were needed until this larva starts pupation (mean 5-7 days). The formation of the adult fleas inside the puparium occurred within 9-15 days (with a maximum hatch at day 12). Adult female fleas having reached the skin of a host start blood sucking within 5 min and prepare to enter the skin. After 24 h, the flea stacked already with two thirds of its body inside the skin. After 40 h, the penetration was completed, and feeding and hypertrophical enlargement started, which was completed on day 6, when eggs became ejected. When studying the morphology of the fleas obtained from different hosts, slight variations were seen, which, however, are not significant for a species separation but may be an indication of the presence of different strains/races or the beginning of such a formation.

Field trial of the efficacy of a combination of imidacloprid and permethrin against Tunga penetrans (sand flea, jigger flea) in dogs in Brazil

In a field trial in Brazil 17 dogs penetrated by females of the jigger flea, Tunga penetrans, were topically treated with a combination of 10% imidacloprid and 50% permethrin (Advantix), while 17 dogs remained untreated. The follow-up controls on days 7, 14, 21 and 28 post-treatment clearly showed that, beginning from day 7, the flea load in treated dogs decreased, so that most of the dogs became free of tungiasis lesions, while in the untreated group the flea load remained high. Since the dogs distribute the flea eggs throughout the village, leading to a high incidence of tungiasis in humans, treatment of dogs probably also decreases the number of cases of tungiasis in the latter.

Determining a diagnostic dose for imidacloprid susceptibility testing of field-collected isolates of cat fleas (Siphonaptera: Pulicidae)

The susceptibility of four laboratory strains of cat fleas, Ctenocephalides felis (Bouche), to imidacloprid was determined by three different laboratories, by using a standardized bioassay protocol. The probit lines generated by the different laboratories were very similar, with LC50 values ranging from 0.32 to 0.81 ppm. Based on these data, a diagnostic dose (DD) of 3 ppm imidacloprid in larval rearing media was provisionally identified for detecting shifts in tolerance, possibly as a consequence of incipient imidacloprid resistance. None of the larvae from the susceptible laboratory strains survived the DD. Eighteen field-collected isolates were evaluated for their susceptibility to imidacloprid and to validate a DD of 3 ppm. Probit lines from 18 field-collected isolates were very similar, with LC50 values ranging from 0.14 to 1.52 ppm. When exposed to the DD, between 3 and 10% of the exposed larvae emerged as adults from only three of the 18 isolates. All other field isolates gave 100% mortality at the DD. Under the criteria established (>5% survivorship at 3 ppm), two isolates would be established on mammalian hosts and more extensive tests conducted to exclude or confirm the presence of resistance. The DD of 3 ppm is robust enough to eliminate most of the susceptible isolates collected until today, yet low enough to identify possible isolates for further testing.

Molecular biological investigations of Brazilian Tunga sp. isolates from man, dogs, cats, pigs and rats

Twenty-four isolates of Tunga were collected from afflicted humans, dogs, cats, pigs and rats in Brazil. To investigate genetic diversity, a hypervariable section of mitochondrial 16S rDNA was amplified using PCR and subsequently sequenced. In order to compare results with another species of the genus Tunga, three isolates of the recently described Tunga trimamillata were also checked. Whereas eleven isolates (five from cats, three from dogs and three from humans) were of identical sequence, thirteen isolates collected from dogs, humans, pigs and rats showed differences in sequence up to 49%, so that the existence of one or more new species of Tunga may be presumed.

Molecular phylogeny of isolates of Ctenocephalides felis and related species based on analysis of ITS1, ITS2 and mitochondrial 16S rDNA sequences and random binding primers

The phylogenetic relationships among 31 different flea isolates representing seven different species were studied by nucleotide sequence comparison of the internal transcribed spacer 1 (ITS1), internal transcribed spacer 2 (ITS2) and/or mitochondrial 16S ribosomal RNA gene (mt16S-rDNA) to examine the patterns of variation. Results show that all regions are useful in discriminating among flea species. In Ctenocephalides felis and Tunga penetrans, some differences in these gene regions occurred among different isolates within the same species. In the latter case, the differences are in the mt16S-rDNA region, with one isolate showing 48% divergence in nucleotide sequence. The taxonomic implications of this result are unclear at present. The gene regions revealed differences between C. felis isolates only after DNA sequencing the PCR products. Further differentiation among C. felis isolates was obtained using four different random binding primers (decamers) and primers for mammalian aldolase to amplify narrow differences in the genome. Using these primers we were able to discriminate between different C. felis isolates and determine that some of the genetic variation coincided with minor differences in response to the control agent imidacloprid. However, overall findings do not support the existence of subspecies of C. felis.

[Humanopathogenic parasites--an unwelcome import]

Humanopathogenic parasites represent a health risk for travelers to tropical countries. They can be picked up by direct contact, via contaminated food and drink, the bites of blood-sucking insects and leeches, as also via direct penetration through the skin. Not only the bite and sting wounds themselves are unpleasant. The true danger to the victim is represented, in particular, by the bacteria, viruses or parasites that are transmitted in this way. They can give rise to protracted diseases such as hepatitis B, cutaneous or intestinal disorders. The most effective preventive measure is exposure prophylaxis.

[Hantavirus-induced acute renal failure. A case report]

A non-ischemic acute renal failure may indicate a hantavirus nephropathy, so that appropriate serological examinations should be done. A 19-year-old man had acutely fallen ill with fever, rhinitis, and arthralgia. Clinically, he presented with a polyuric renal failure as well as hypertension, proteinuria, erythro- and leucocyturia. Serologically, IgG- and IgM-hantavirus antibodies were found against the Central European variant of hantavirus Dobrava. At renal biopsy, tubular epithelial swelling, vacuolization, and necrosis as well as interstitial hemorrhages were seen. Electron microscopically, virion particles with a gridlike surface structure as well as with the shape and dimension evident of hantaviruses could be detected in the nucleus and cytoplasm of renal tubular cells. After a clinical course of 3 weeks, the patient was free of complaints and cured with a restitutio ad integrum.

Evidence of horizontal transmission of feline leukemia virus by the cat flea ( Ctenocephalides felis)

The feline leukemia virus (FeLV) is a naturally occurring and widespread retrovirus among domestic cats. The virus is mainly transmitted horizontally through saliva, blood and other body fluids by close contact between cats. Vectors other than cats, e.g. blood-sucking parasites, have not been reported. This study tested the vector potential of the cat flea ( Ctenocephalides felis) for FeLV. In a first feeding, fleas were fed for 24 h with blood from a FeLV-infected cat with persistent viremia. FeLV could be detected in the fleas, as well as in their feces. Fleas were then divided in two populations and fed in a second feeding for 5 h or 24 h with non-infected non-viremic blood. FeLV was again detected in the fleas and their feces. In addition, the two resulting blood samples of the second feeding were subsequently tested for FeLV and both samples were positive for FeLV RNA. The cat flea transmitted the FeLV from one blood sample to another. In a third feeding, the same populations of fleas were fed again with non-infected blood for 5 h or 24 h. This time FeLV was not detected in the fleas, or in the feces or blood samples. Results show that cat fleas are potential vectors for FeLV RNA in vitro and probably also in vivo.

No evidence of Wolbachia endosymbiosis with Loa loa and Mansonella perstans

Endosymbiotic Wolbachia bacteria from different filarial species, including major pathogens of humans such as Wuchereria bancrofti, Brugia malayi and Onchocerca volvulus, seem to play an important role in the development, viability and fertility of these worms. Wolbachia trigger inflammatory host responses as well as adverse reactions against standard treatment regimens and are therefore under investigation as novel treatment targets. We investigated whether Wolbachia are also endosymbiotic in Loa loa and Mansonella perstans. In both male and female adult L. loa, we found no evidence of bacteria by light or transmission electron microscopy. Furthermore, Wolbachia-specific PCR was negative in both L. loa and M. perstans microfilariae. The absence of Wolbachia in both filarial species therefore discourages the use of antibiotics as an adjunct or alternative approach to current treatment concepts for both loiasis and mansonelliasis perstans.

Electron microscopic study of in vitro cultures of Hammondia heydorni (Berlin 1996) tachyzoites after passages through dogs, mice, rats, guinea pigs and jirds

This study describes the fine structure and reproduction of tachyzoites of Hammondia heydorni (isolate Berlin 1996) after in vitro cultivation of stages isolated from serial passages between dogs and various intermediate hosts such as mice, rats, guinea pigs, jirds, knock-out mice, goats and sheep. The tachyzoites are identical with respect to their ultrastructural features to the corresponding stages of the NC-1-strain of Neospora caninum. This fact conforms with other already published data and underlines our opinion that the recently redescribed N. caninum Dubey et al. 2002 is a synonym of the previously described H. heydorni (Tadros and Laarman 1976) Dubey 1977.

Synergistic effects of pyrantel and the febantel metabolite fenbendazole on adult Toxocara canis

Pyrantel embonate and febantel are both constituents of Drontal Plus and Drontal Puppy broad spectrum anthelmintics for dogs. The effects of pyrantel and the febantel metabolite fenbendazole were investigated against Toxocara canis in-vitro by studying changes in worm motility and tissue damage. Pyrantel and fenbendazole were added to worms incubated in media for 8 h at the following concentrations: pyrantel: 12.2 microg, 25 microg, or 50 microg; fenbendazole: 50 microg, 100 microg or 200 microg; mixture of pyrantel and fenbendazole: 12.2 microg p + 50 microg f, 25 microg p + 100 microg f, 50 microg p + 200 microg f. Following this 8 h incubation period, one group of the worms was immediately fixed and studied by light- and electron microscopical examination. Other groups have been observed for further 8 h periods up to 56 hours and then studied in the same way.

Development of a larval bioassay for susceptibility of cat fleas (Siphonaptera: Pulicidae) to imidacloprid

Strategies for controlling cat fleas, Ctenocephalidesfelisfelis (Bouché), have undergone dramatic changes in the past 5 yr. With the advent of on-animal treatments with residual activity the potential for the development of insecticide resistance increases. A larval bioassay was developed to determine the baseline susceptibility of field-collected strains of cat fleas to imidacloprid. All four laboratory strains tested showed a similar level of susceptibility to imidacloprid. Advantages of this bioassay are that smaller numbers of fleas are required because flea eggs are collected for the test. Insect growth regulators and other novel insecticides can also be evaluated. Using a discriminating dose, the detection of reduced susceptibility in field strains can be determined with as few as 40 eggs.

[The tick stings! Observations on a misnomer]]

Dermatology enjoys a unique distinction of visualizing its subject matter and should attain complete unity between a dermatologic term and the clinical concept therewith expressed. Clear and definite terminology seems indispensable. Unfortunately wrong designations sanctioned by daily use are incorporated in official nomenclature. How parasitology tells us that a tick stings and that a "tick bite" is a misnomer is detailed in this article.

Cyclic transmission of Neospora caninum: serological findings in dogs shedding oocysts

In a previous paper we demonstrated that Hammondia heydorni-like oocysts isolated in 1996 from a naturally infected dog could not be distinguished from the isolate Neospora caninum NC-1. The isolate, designated as H. heydorni-Berlin-1996, was cyclically transmitted using dogs as the final hosts. The present study provides information on the antibody responses of the dogs used for the cyclical transmission of this isolate. The majority of dogs that had shed oocysts showed no sero-conversion with respect to N. caninum tachyzoite surface or immunodominant antigens, either in the indirect fluorescent antibody test or in two Western-blot-based tests. In addition to the examination of responses to immunodominant antigens, we also analysed the antibody reactions of dogs to a high-molecular-weight antigen (152 kDa) in the tachyzoite antigen preparation. The antibodies against this antigen appeared after the dogs had been fed infected intermediate host tissues and shed oocysts. The reaction was observed in dogs between day 35 and day 447 after feeding of intermediate host tissues. Therefore, our study provides initial information on a 152 kDa tachyzoite antigen, which might be a suitable candidate to identify dogs with a history of shedding N. caninum oocysts.

Hammondia heydorni-like oocysts shed by a naturally infected dog and Neospora caninum NC-1 cannot be distinguished

This study describes transmission experiments using Hammondia heydorni-like oocysts isolated in 1996 from a naturally infected dog. The isolate was designated as H. heydorni-Berlin-1996. Examination of sera from infected intermediate hosts showed immunoblot reactions that resembled patterns observed after Neospora caninum NC-1 infection. Furthermore, N. caninum DNA could be demonstrated in tissue samples (e.g. heart, brain) of experimentally infected intermediate hosts and in oocyst preparations from H. heydorni-Berlin-1996. The isolated oocysts did not induce any detectable disease in any of the inoculated adult intermediate hosts (goats, sheep, gerbils, guinea pigs, multimammate rats, BALB/c mice, SCID mice), even upon immunosuppression. Furthermore, neither histological lesions nor parasite stages could be identified in the tissues of all fetuses recovered from two multimammate rats that had been infected prior to pregnancy. An experiment with one dog fed a second time on infected intermediate host tissue indicated that immunity may prevent repeated oocyst shedding in N. caninum-infected dogs. In addition, the study clearly demonstrates that N. caninum can be readily transmitted by dogs that have ingested exclusively skeletal muscles of infected intermediate hosts. Therefore, the study has consequences for the recommendations for farmers to prevent postnatal transmission of N. caninum to cattle. It indicates that feeding of any tissues of potential intermediate hosts (including sheep, goats, rodents) to final hosts may induce the shedding of oocysts in these hosts and thus pose a risk for post-natal infection of cattle. With respect to oocyst morphology and the infectivity of muscle tissues for final hosts, no differences were seen in comparison with observations made in the past on Isospora bigemina/I. heydorni/H. heydorni. Therefore, earlier studies made on I. bigemina/I. heydorni/H. heydorni have to be re-evaluated critically to determine whether they may have included N. caninum or other protozoan parasites that use dogs as final hosts and have an oocyst morphology resembling that of I. bigemina/I. heydorni/H. heydorni.

Comparative molecular investigation of Nc5-PCR amplicons from Neospora caninum NC-1 and Hammondia heydorni-Berlin-1996

The clinical relevance of Neospora caninum as a cyst-forming coccidian parasite is increasingly acknowledged within veterinary medicine, although the pathways of transmission are far from being solved. The parasite is well known for causing diaplacental infections in cows associated with abortion and/or severe damage of the fetus. In addition, it may cause neuromuscular disease in dogs, which thus apparently act as intermediate hosts as well as final hosts. In our previous studies, we have demonstrated that molecular diagnosis of N. caninum infections has a high performance when a highly sensitive polymerase chain reaction (PCR) targeted to the Nc5 region of the parasite is used. The present study indicates that the high sensitivity of the PCR is the consequence of a target dose effect which reflects a high redundancy of Nc5-type sequences within the genome of the parasite. The PCR was shown to amplify a set of DNA molecules exhibiting significant sequence differences. A complex composition of Nc5-type sequences was observed in the parasite isolate N. caninum NC-1 but also in another isolate, designated Hammondia heydorni-Berlin-1996. Investigation of the infection pattern of this parasite in its intermediate and final canine hosts showed it to be indistinguishable from N. caninum NC-1.

Further remarks on Hammondia hammondi and the taxonomic importance of obligate heteroxeny

In this opinion-paper reasons are given why Hammondia hammondi cannot be considered as a separate species, but should be kept as a species of the genus Toxoplasma, if not a strain of Toxoplasma gondii.

In vivo and in vitro effects of imidacloprid on sheep keds (Melophagus ovinus): a light and electron microscopic study

The effects of imidacloprid (Advantage) on sheep keds (Melophagus ovinus Linne 1758) were studied in vivo and in vitro by means of direct observation (monitored on video tape) and by light and electron microscopy. It was found that: 1. Imidacloprid acted rapidly on all motile stages of the sheep keds. Within 3-4 min after exposure they became immobile and their legs and the abdomen started tetanic trembling movements for 15-30 min, leading to death. 2. The compound is apparently taken up by the body, since it also acted on those sheep keds that had been exclusively exposed to imidacloprid-contaminated filter papers. 3. The compound is available and active for more than 1 month in the wool of sheep; even rainfall does not reduce its efficacy. Body contact between treated mother sheep and their lambs protects them from infestation with these ectoparasites. 4. The compound initiates an ultimately lethal destruction of the ganglia, nerve chords and related muscle fibers, as can be seen in electron micrographs.

Comparative study on the effects of three insecticides (fipronil, imidacloprid, selamectin) on developmental stages of the cat flea (Ctenocephalides felis Bouché 1835): a light and electron microscopic analysis of in vivo and in vitro experiments

The effects of three insecticides (fipronil, imidacloprid and selamectin) on developmental stages of cat fleas (Ctenocephalides felis) were studied in vivo, in vitro and by means of light and electron microscopy. The results were documented by video. Adult fleas were attached to the skin of dogs that had been treated 7 days before with one of the three compounds. Furthermore, adult fleas were exposed exclusively to the hair and skin debris of such treated dogs or were placed on filter papers that had been impregnated with one of these three compounds or with the blood of treated dogs. Larval fleas were exposed to hair of treated dogs, to debris obtained by combing treated dogs, to dried blood samples of treated dogs or were placed onto filter papers impregnated with one of the three compounds. In these experiments with adult and larval fleas, it was noted that none of the three insecticides had a repellent effect on adult or larval fleas. Imidacloprid was the only compound that acted exclusively by body contact, and was apparently taken up by adult and larval fleas via the thin, non-sclerotized intersegmental membranes of the flea's body, shown when flea stages were exposed to hairs taken from dogs treated with one of the compounds or placed onto drug-impregnated filter papers. Imidacloprid killed larvae and adult fleas within 1 h, while it took at least 24 h until all adult fleas had died on fipronil- or selamectin-treated dogs, thus allowing longer feeding periods, increasing the risk of transmission of flea-derived diseases. Flea larvae covered with debris from dogs topically treated 7 days before with fipronil, imidacloprid or selamectin died, like the untreated control, within 16-28 h after exposure. This was, however, probably mainly due to a drying effect. Adult and larval fleas exposed to filter papers impregnated with the blood of treated dogs survived longer than 7 days, as did the untreated controls. All three drugs apparently acted on nerves and muscles and thus stopped motility.

Synergistic action of a cyclic depsipeptide and piperazine on nematodes

The present study describes the synergistic effects of the cyclic depsipeptide BAY 44-4400 and piperazine in the treatment against the nematodes Trichinella spiralis, Heligmosomoides polygyrus, and Heterakis spumosa. The in vitro anthelmintic activity of a combination of the two compounds (1.7 motility units) against T. spiralis larvae was significantly higher than the sum of the individual drug effects (1.3 motility units). With regard to the rate of expulsion of H. polygyrus worms from the intestine of infected mice, an additive effect was observed; piperazine alone exerted an efficacy of 54.4% and BAY 44-4400 alone, one of 44.4%, whereas the combination of these compounds had an efficacy of 97.5%. With regard to the expulsion of H. spumosa worms, the effect of the combination was more than 5 orders of magnitude greater than the sum of the effects of the single compounds, i.e., there was a considerable potentiation of the actions of BAY 44-4400 and piperazine. Moreover, the combination exerted a significantly higher degree of degenerative effects on the intestine and on the nerve chords of H. spumosa as compared with the single compounds.

Molecular genetic characterization and subcellular localization of Theileria annulata mitochondrial heat-shock protein 70

A Theileria annulata mitochondrial heat-shock protein of the 70-kDa family (Tamthsp70) was isolated by screening of the cDNA library of a T. annulata-infected bovine lymphoblastoid cell line with an antibody raised against T. annulata schizonts. The Tamthsp70 coding sequence was found to be most closely related to a previously reported mitochondrial hsp70 gene of Eimeria tenella exhibiting a similarity of 67% with mitochondrial hsp70 genes of eukaryotic plants (Pisum sativum, Phaseolus vulgaris) and with dnaK proteins of prokaryotes (Rhizobium meliloti, Agrobacterium tumefaciens). The Tamthsp70 mRNA is expressed within the sporozoite, schizont, and merozoite stages of the parasite, which suggests that it is constitutively transcribed throughout the life cycle. The gene encodes a polypeptide of 681 amino acids and exhibits a mitochondrial targeting sequence and several sequence motifs common to mitochondrial hsp70 and prokaryotic dnaK proteins. The protein level of the Tamthsp70 protein after heat shock decreased slightly during the exposure of infected cells to a temperature of 42 degrees C in comparison with cells cultured at 37 degrees C. By immunofluorescence the protein was located in the area in which the schizonts reside within infected cells. Immunoelectron microscopy showed that the hsp70 protein was predominantly localized in the mitochondria of the parasites. However, it was also found in small amounts in the cytoplasm of the parasite and host cell. This indicates (1) that Tamthsp70 is very probably translated in the parasite cytoplasm and then transported across the mitochondrial membrane into the mitochondrial matrix and (2) that it is transported across the parasite membrane into the host-cell cytoplasm.

Neospora caninum: is it really different from Hammondia heydorni or is it a strain of Toxoplasma gondii? An opinion

The published data concerning Toxoplasma gondii, Hammondia hammondi, H. heydorni and Neospora caninum on one side and between T. gondii on the other were neglected by most authors. As conclusion we are convinced that there are only two valid species: Isospora (Toxoplasma) gondii and Hammondia heydorni. The first includes as a strain H. hammondi and the latter N. caninum. In any case there is absolutely no reason (with respect to general Zoological nomenclature) to create new genera!

Fly larvae and pupae as vectors for scrapie

We analysed experimental transmissibility of the scrapie agent by natural vectors. A fly, Sacrophaga carnaria, fed with brains of scrapie-infected hamsters in different developmental stages caused scrapie in hamsters after they ate fly extracts.

Characterization of a genomic region encoding the 32-kDa dense granule antigen of Sarcocystis muris (Apicomplexa)

Two subgenomic libraries constructed from Sarcocystis muris total DNA were screened with a cDNA probe, specific for a 32-kDa protein associated with the dense granules. Two clones reacted positively and were isolated, gDG 32/1 and gDG 32/2. Genomic clone gDG32/1 and part of clone gDG 32/2 have been sequenced. The composite nucleotide sequence of these genomic clones comprises 4.34 kb. It contains a 5' region of 2.14 kb, a first coding region (222 bp, exon I), a noncoding region (608 bp, intron), a second coding region (660 bp, exon II), and a 3' region of 693 bp. The upstream region shows a eukaryotic promoter structure and a consensus sequence for the 5' and 3' splicing sites. Thus the open reading frame (ORF DG32) coding for the 32-kDa protein of the dense granules of S. muris cyst merozoites is interrupted by an intron. To our knowledge, dg32 is the first sarcosporidian mosaic gene to be characterized.

Isolation and characterization of a cDNA clone encoding a thiol proteinase of Sarcocystis muris cyst mero' zoites (Apicomplexa)

A cDNA library of Sarcocystis muris cyst merozoites was screened using a digoxigenin-labeled probe. This probe was derived from a 504-bp polymerase-chain-reaction fragment representing part of a thiol proteinase. Several cDNA clones were isolated, one of which (PH08) consists of a nucleotide sequence of 1694 bp and encodes the complete prepropolypeptide of a cathepsin L-like proteinase. PH08 contains an open reading frame of 394 amino acid (aa) residues with a 46-residue signal sequence, which is followed by a 129-residue propeptide and 219 aa residues of the mature enzyme. Two potential glycosylation sites and a putative polyadenylation signal were also identified. The occurrence of the highly conserved interspersed ERFNIN aa motif, not found in cathepsin B-like proteinases, suggests the classification of the enzyme as a cathepsin L-like proteinase. Results worked out in this study will enable production of the recombinant thiol proteinase of S. muris cyst merozoites necessary for study of the substrate specificity as well as other biochemical parameters of this enzyme.

Effects of imidacloprid on adult and larval stages of the flea Ctenocephalides felis after in vivo and in vitro application: a light- and electron-microscopy study

The effects of imidacloprid (Advantage) on the larval and adult stages of cat fleas (Ctenocephalides felis) were studied in vivo and in vitro by means of light and electron microscopy. It was found that: 1. The compound acted rapidly on both larval and adult fleas, killing both stages within 20 min of contact. 2. When applied as a spot-on to the skin of dogs, the compound localized in the water-resistant lipid layer of the skin surface and in the hairs but not in the blood. 3. Thus, the compound was not taken up during sucking of the flea but was absorbed via the thin intersegmental membranes, since larval and adult fleas that had only external contact with imidacloprid-impregnated paper or with shaved hairs from imidacloprid-treated dogs showed reactions similar to those shown by fleas sitting on treated skin. 4. The compound led to a continuous blockage of insect-specific nicotinic-acetylcholine receptors (nAChR), causing tetanic muscle cotractions within minutes of exposure. This manifested as intense trembling of the legs and pumping movements of the body. The affected flea stages remained motionless while the nerves and muscles were constantly and irreversibly destroyed due to hyperactivity. The ganglia of the head and thorax and the striated muscles of the flea body and legs were damaged first, whereas the intestinal movements (e.g., visible in larvae) took longer to exhibit damage. In summary, these studies show that imidacloprid kills larval and adult flea stages rapidly via the same mode of action and thus prevents the development of flea populations in human or animal dwellings.

Review: Theileria schizonts induce fundamental alterations in their host cells

The sporozoites of Theileria annulata and T. parva invade bovine leukocytes, where they differentiate into schizonts. The latter can immortalize and induce fundamental changes in their host cells. T. annulata infects mainly major histocompatibility complex class II cells, whereas T. parva preferentially transforms T-lymphocytes, which proliferate continuously without the need for exogenously added growth factors. Most of the cell lines appear to be independent of a growth factor but may express several cytokines that influence the outcome of the disease. The mechanisms underlying this transformation are not well understood. The infected cells show increased activity of casein kinase II and Jun NH2-terminal kinase (JNK), whereas extracellular signal-related kinase 1 and 2 and P38 are not activated. In addition, several transcriptional factors such as NFkB and AP-1 are activated. It has been postulated that parasite proteins either expressed on the surface of the schizonts or secreted into the host cell cytoplasm may interfere with the signal-transduction pathway of the host cells. A possible candidate may the casein kinase II homologue that was identified in schizonts of both T. annulata and T. parva.

Review: the cellular basis of the immunity to and immunopathogenesis of tropical theileriosis

The intracellular protozoan parasite Theileria annulata causes a severe and often fatal disease of pure and crossbred cattle in tropical and subtropical countries. Animals that recover from the infection are immune against challenge with homologous parasite strains. In the present review we refer to the role of immunocompetent cells and their products in containing the infection or in facilitating the progress of the disease. Parasite-infected host cells produce cytokines, which, depending on their concentration and timing of production, may enhance the establishment of the infection. Thus, cell lines producing high levels of proinflammatory cytokines cause severe postvaccinal reactions when inoculated into cattle. This may be supported by an aberrant non-specific activation of naive T-cells, leading to the production of high levels of gamma-interferon (IFN-y). Under these circumstances development of the specific immune response may be inhibited. At this stage, innate immune reactions are operating to contain the infection. Natural killer cells and macrophages may represent the most important part of this immunity. Antibodies and specific T-lymphocytes, CD4+ T-cells and cytotoxic T-lymphocytes (CTLs), play the most important role in a challenge infection. In this context, CD4+ T-cells produce cytokines required for the clonal expansion of CTLs that kill their target cells in a major histocompatibility complex (MHC) class I-restricted manner. In addition, CD4+ T-cells produce macrophage-activating cytokines such as IFN-gamma. Such activated macrophages produce mediators such as NO, which destroy the intracellular schizonts. Attempts have been directed toward the identification of parasite antigens involved in the induction of immunity. To date, only a limited number of sporozoite and merozoite antigens have been identified and examined for their immunogenicity, and the protection achieved is partial. An effective vaccine must include schizont proteins, notably, those proteins that are secreted into the host cell cytoplasm because these may have access to the MHC class I and II compartments to be presented to CTLs and CD4+ T-cells, respectively. Several schizont proteins have been identified and these are now under investigation.