Simultaneous Determination of Neutron-Induced Fission and Radiative Capture Cross Sections from Decay Probabilities Obtained with a Surrogate Reaction.

Reliable neutron-induced-reaction cross sections of unstable nuclei are essential for nuclear astrophysics and applications but their direct measurement is often impossible. The surrogate-reaction method is one of the most promising alternatives to access these cross sections. In this work, we successfully applied the surrogate-reaction method to infer for the first time both the neutron-induced fission and radiative capture cross sections of ^{239}Pu in a consistent manner from a single measurement. This was achieved by combining simultaneously measured fission and γ-emission probabilities for the ^{240}Pu(^{4}He,^{4}He^{'}) surrogate reaction with a calculation of the angular-momentum and parity distributions populated in this reaction. While other experiments measure the probabilities for some selected γ-ray transitions, we measure the γ-emission probability. This enlarges the applicability of the surrogate-reaction method.

Acaricidal activity of fluralaner against Ornithodoros moubata and Ornithodoros erraticus argasid ticks evaluated through in vitro feeding.

Ornithodoros erraticus and Ornithodoros moubata are argasid tick vectors that transmit severe diseases such as African swine fever and human relapsing fever. Elimination of the synanthropic populations of these vectors would facilitate the control of these diseases. Fluralaner is a novel isoxazoline that selectively blocks the GABA- and glutamate-gated channels, providing potent insecticidal and acaricidal activity. The aim of the current study was to provide quantitative data on the susceptibility of males, females and third nymphal instar of O. erraticus and O. moubata to fluralaner through in vitro feeding exposure. Fluralaner activity against these developmental stages and species was assessed by feeding the ticks on ovine blood medicated with decreasing fluralaner concentrations between 1 and 10-8µg/mL. Tick mortality was measured at 4, 24 and 48h and 1, 2 and 3 weeks post-feeding. Tests included solvent-treated and untreated blood controls. Fluralaner was extremely active against O. erraticus, with mean lethal concentrations 50 (LC50) and 95 (LC95) of 2.0×10-8 and 5.4×10-8µg/mL, respectively. Fluralaner was also highly active against O. moubata, showing a mean LC50 of 1.5×10-6µg/mL and a mean LC95 of 1.8×10-3µg/mL. In the latter species, the most susceptible life stages were the females (LC95 1.4×10-4µg/mL). Fluralaner demonstrated potent acaricidal activity against all developmental stages of O. erraticus and O. moubata tested, in the first 48h after in vitro feeding. Therefore, fluralaner has the potential to provide very high acaricidal efficacy to multiple argasid tick species via feeding exposure and could be included as an acaricidal agent in integrated programmes for the control of argasid tick vectors and argasid tick-borne diseases.

Serological Surveillance and Direct Field Searching Reaffirm the Absence of Ornithodoros Erraticus Ticks Role in African Swine Fever Cycle in Sardinia.

African swine fever (ASF), one of the most important diseases of swine, has been endemic in the Italian island of Sardinia for more than 35 years. During these decades, several strategies and eradication efforts have been implemented in the island with limited success. Strong climatic and ecological similarities exist between Sardinia and one area of the Iberian Peninsula where Ornithodoros erraticus ticks were involved in the persistence of ASF from 1960 to 1995. This fact leads to the hypothesis that, potentially, Ornithodoros ticks could be also involved in the ASF cycle in Sardinia, thus accounting for some of the reoccurring ASF outbreaks in this island. Initial efforts aimed at detection of Ornithodoros ticks in Sardinia were performed during the 1970s/1980s with no positive results. Accordingly, the absence of Ornithodoros ticks in Sardinia has been generally accepted. However, since a new and reinforced ASF eradication programme has been recently launched in Sardinia, it is essential to clarify the presence and role of these soft ticks in the epizootiology of ASF in this island. For that purpose, 1767 porcine serum samples collected from all around the island (1261 from domestic and 506 from wild boar) were analysed by ELISA for antibodies to salivary antigens of Ornithodoros erraticus. In addition, Ornithodoros ticks were directly searched in a number of pig premises that have suitable habitats for these ticks and were located in areas repeatedly affected by ASF. Only one serum sample resulted positive in the serological assay, and no Ornithodoros ticks were collected in none of the premises. These results indicate that these soft tick species are not involved in the epizootic cycle of ASF in Sardinia and highlight the importance of controlling other risk factors still present in the island for effectively eradicate the disease.

TSGP4 from Ornithodoros moubata: molecular cloning, phylogenetic analysis and vaccine efficacy of a new member of the lipocalin clade of cysteinyl leukotriene scavengers.

Recently obtained evidence indicated that an orthologue of the O. savignyi TSGP4 salivary lipocalin was present in the saliva of O. moubata. TSGP4 is known to act as a cysteinyl leukotrienes scavenger helping in the prevention of inflammation and oedema at the tick bite site. Since this function seems to be crucial for successful tick feeding, the novel O. moubata TSGP4 turned into a potential vaccine target. The purposes of the current work were: (i) to clone and characterize the O. moubata TSGP4 and, (ii) to produce it as recombinant to evaluate its protective efficacy as vaccine antigen. The results of these experiments indicated that the O. moubata TSGP4 shows high sequence and structural identity with the O. savignyi orthologue suggesting identical function in the physiology of the tick-host relationship. The mature native TSGP4 is not immunogenic when it is inoculated to host with tick saliva during feeding, but host vaccination with the recombinant protein TSGP4 in Freund's adjuvants induced strong humoral immune responses that recognized both the recombinant and native TSGP4 and protected the host with a 14.1% efficacy. So, the O. moubata TSGP4 can be considered a silent salivary antigen; however, in the light of the current results, its inclusion in the current repertory of protective antigens to be targeted by anti-tick vaccines could be controversial.

Investigation into the Epidemiology of African Swine Fever Virus at the Wildlife - Domestic Interface of the Gorongosa National Park, Central Mozambique.

An epidemiological study of African swine fever (ASF) was conducted between March 2006 and September 2007 in a rural area adjacent to the Gorongosa National park (GNP) located in the Central Mozambique. Domestic pigs and warthogs were sampled to determine the prevalence of antibodies against ASF virus and the salivary antigens of Ornithodoros spp. ticks, while ticks collected from pig pens were tested for the presence of ASFV. In addition, 310 framers were interviewed to gain a better understanding of the pig value chain and potential practices that could impact on the spread of the virus. The sero-prevalence to ASFV was 12.6% on farms and 9.1% in pigs, while it reached 75% in warthogs. Approximately 33% of pigs and 78% of warthogs showed antibodies against salivary antigens of ticks. The differences in sero-prevalence between farms close to the GNP, where there is greater chance for the sylvatic cycle to cause outbreaks, and farms located in the rest of the district, where pig to pig transmission is more likely to occur, were marginally significant. Ornithodoros spp. ticks were found in only 2 of 20 pig pens outside the GNP, and both pens had ticks testing positive for ASFV DNA. Interviews carried out among farmers indicated that biosecurity measures were mostly absent. Herd sizes were small with pigs kept in a free-ranging husbandry system (65%). Only 1.6% of farmers slaughtered on their premises, but 51% acknowledged allowing visitors into their farms to purchase pigs. ASF outbreaks seemed to have a severe economic impact with nearly 36% of farmers ceasing pig farming for at least 1 year after a suspected ASF outbreak. This study provides the first evidence of the existence of a sylvatic cycle in Mozambique and confirms the presence of a permanent source of virus for the domestic pig value chain.

Review of the sylvatic cycle of African swine fever in sub-Saharan Africa and the Indian ocean.

African swine fever (ASF) is a major limiting factor for pig production in most of the countries in Sub-Saharan Africa and the Indian Ocean. In the absence of vaccine, a good understanding of the ecology and epidemiology of the disease is fundamental to implement effective control measures. In selected countries of Southern and East Africa, the association between Ornithodoros moubata ticks and warthogs has been described in detail in the literature. However, for many other countries in the region, information related to the sylvatic cycle is lacking or incomplete. In West African countries, for instance, the role of wild pigs in the epidemiology of ASF has never been demonstrated and the existence and potential impact of a sylvatic cycle involving an association between soft ticks and warthogs is questionable. In other countries, other wild pig species such as the bushpigs (Potamochoerus spp.) can also be asymptomatically infected by the virus but their role in the epidemiology of the disease is unclear and might differ according to geographic regions. In addition, the methods and techniques required to study the role of wild hosts in ASF virus (ASFV) epidemiology and ecology are very specific and differ from the more traditional methods to study domestic pigs or other tick species. The aim of this review is (i) to provide a descriptive list of the methodologies implemented to study the role of wild hosts in African swine fever, (ii) to compile the available knowledge about the sylvatic cycle of ASFV in different regions of Sub-Saharan Africa and the Indian Ocean in addition to the one that has been described for East and Southern Africa, and (iii) to discuss current methodologies and available knowledge in order to identify new orientations for further field and experimental surveys.

Comparative proteomic analysis of Fasciola hepatica juveniles and Schistosoma bovis schistosomula.

Protein interactions between host and parasites can influence the infection success and severity. The aim of this investigation was to identify the proteins from two trematodes potentially localized at the host-parasite interface. We performed the proteomic profiles from in vivo obtained immature lung stage Schistosoma bovis schistosomula and in vitro excysted juveniles from Fasciola hepatica, parasites of ruminants and man usually giving rise to chronic infections. Proteomes from those parasites were obtained after digestion with trypsin and the peptides generated were identified by mass spectrometry, both before and after parasites' treatment with 70% methanol. The comparison of the two proteome sets from each parasite and between them, the analysis of their relative abundance and of their potential exposure to the host from living parasites, together with the specific immunolocalization of two of the identified molecules, show that this approach could assist in the identification of parasite exposed proteins and in the definition of molecules common for the two parasites with potential interaction with the host. Further characterization of these molecules could guide to define new common anti-parasitic targets and potential vaccine candidates.

Assessment of interactions between African swine fever virus, bushpigs (Potamochoerus larvatus), Ornithodoros ticks and domestic pigs in north-western Madagascar.

Since its introduction in Madagascar in 1998, African swine fever (ASF) has severely affected national pig production and persists as a common disease in that country. Two of its natural hosts in the African continent, the bushpig (Potamochoerus larvatus) and tick vectors of the Ornithodoros moubata complex, are reported in west and central regions of the island. However, their role in the maintenance and transmission of the virus has been insufficiently studied. In this work, we tried to assess their potential role in the epidemiology of the disease in Madagascar, by assessing the levels of interaction between (i) ASF virus (ASFV) and bushpigs and (ii) between soft ticks and domestic and wild suids in north-western Madagascar. Twenty-seven sera and 35 tissue samples from bushpigs were collected and analysed for the presence of anti-ASF antibodies and viral DNA. In addition, the sera from 27 bushpigs and 126 domestic pigs were analysed with an ELISA test for the detection of antibodies against salivary antigens from Ornithodoros ticks. No circulation of ASFV or anti-ASFV antibodies nor anti-tick antibodies were detected in bushpigs. However, seven of the domestic pig sera (5.6% of the total sample population) were antibody positive for O. moubata antigens. The probability of freedom from ASFV in the bushpig population using Bayesian statistical methods ranged between 73% and 84%. The probabilities of absence of anti-tick antibodies in domestic and wild pigs were estimated at 63% and 71%, respectively. These preliminary results suggest that bushpigs are unlikely to play a significant role in the maintenance and transmission of ASFV in Madagascar. Nevertheless, further ASFV surveys are needed on that species to confirm this assumption. In addition, the presence of antibodies against O. moubata in domestic pigs suggests that soft ticks may be able to maintain ASFV within a domestic pig cycle in areas of Madagascar where they remain present.

Increased prevalence of Rickettsia aeschlimannii in Castilla y León, Spain.

We report the increased prevalence recorded in recent years of Rickettsia aeschlimannii in Hyalomma marginatum marginatum ticks removed from human subjects in Castilla y León (NW, Spain). Additionally, a simultaneous infection with R. aeschlimannii and Anaplasma phagocytophilum in two H. marginatum marginatum ticks is reported for the first time.

The seroprevalence of human infection with Rickettsia slovaca, in an area of northern Spain.

An epidemiological survey was undertaken to explore human exposure to Rickettsia slovaca in two provinces of northern Spain. When IFAT were used to test 200 members of the general population for antibodies to rickettsiae of the spotted-fever group, six (3.3%) were found positive, presumably, since Dermacentor is one of the most common genera of human-biting tick in the study area, for antibodies to R. slovaca. Thirty-one (16.9%) of an additional 183 subjects who presented shortly after being bitten by ticks were also found seropositive. The difference in seroprevalence between the general and the tick-bitten populations was significant. Subject gender had no influence on seroprevalence in either population, although, in the tick-bitten group, age and occupation did have a significant influence on the prevalence recorded. Immunoblotting was used to confirm the presence of antibodies in the five subjects, all from the tick-bitten group, found to have acute infections. Three D. marginatus ticks obtained from three of these acute cases were found PCR-positive for R. slovaca DNA.

Detection of antibodies to tick salivary antigens among patients from a region of Spain.

With a view to determine which tick species bite humans most frequently in the province of Soria (Spain) and to know whether these species act as vectors of Rickettsia conorii and/or Borrelia burgdorferi, we analysed the presence of antibodies against salivary proteins of several tick species and of antibodies against R. conorii and B. burgdorferi sensu lato in 102 samples of serum. The sera were collected from 63 patients who were treated for tick bites at the health services of the Soria Health Area. Thirty-nine percent of the patients displayed antibodies against Dermacentor marginatus; 21% against Ixodes ricinus, and 6% against Rhipicephalus sanguineus. IgM antibodies against R. conorii were found in 15 patients, but none of the patients included in the study displayed IgG/IgM Abs against B. burgdorferi sensu lato. In 30% of the patients bitten by I. ricinus and in 24% bitten by D. marginatus, antibodies against R. conorii were found. None of the patients who had been bitten by R. sanguineus expressed antibodies against this pathogen. The results obtained here suggest that D. marginatus and I. ricinus are the main vectors of the spotted fever group rickettsiae in our environment and that the role of R. sanguineus in the transmission of these rickettsiae is debatable.

Tick-bite-induced anaphylaxis in Spain.

Although there are very few reports of human anaphylaxis induced by tick bites, two such cases have recently been seen in Salamanca, Spain. To identify the tick species responsible, salivary-gland extracts from six species of hard tick and two of soft tick were prepared and used as allergens/antigens in skin-prick tests and serological analyses. For each case, the results of the skin tests were positive for several species of hard tick but negative for the soft ticks. ELISA and western blots revealed high titres of IgG against hard ticks (but not soft ticks) in the sera from both cases. However, serum from only one of the cases was found to be ELISA- and western-blot-positive for tick-specific IgE. Accordingly, the anaphylaxis seen in one case was IgE-mediated whereas that in the other case appeared to be IgE-independent. In both cases, most of the tick-specific antibodies only recognized carbohydrate epitopes. High levels of cross-reactivity between the salivary-gland extracts from several species of hard tick made it impossible to identify which species was responsible for each anaphylactic reaction, although the immunological results seem to point to Ixodes ricinus.

Molecular detection of Ehrlichia phagocytophila genogroup organisms in larvae of Neotrombicula autumnalis (Acari: Trombiculidae) captured in Spain.

Twenty unfed larvae of Neotrombicula autumnalis (Acari: Trombiculidae) collected on vegetation in the north of Spain were examined by polymerase chain reaction for Borrelia burgdorferi (s.l.). rickettsiae, and the Ehrlichia phagocytophila genogroup. At least 10% of the larvae were found to contain granulocytic ehrlichiae. Because the larvae were unfed, they would necessarily have inherited the bacteria through a transovarian transmission pathway.

Purification, N-terminal sequencing and diagnostic value of the major antigens of Ornithodoros erraticus and O. moubata.

To enhance the specificity and sensitivity of serological detection of swine exposed to Ornithodoros erraticus or O. moubata, we purified the 158, 186, 215 and 260 kDa antigens from the former species and the designated (owing to their MW and charge) 19C, 17A, 20A1 and 20A2 antigens of the latter by HPLC and gel electroelution methods. All the O. erraticus antigens share epitopes and are difficult to purify individually by reverse phase and ion-exchange chromatography due to their molecular similarity. Tested individually by ELISA, all of them give the same optical densities (OD) with anti-O. erraticus sera, and these ODs are always lower with anti-immature than with anti-adult sera. Although immature and adult specimens have the same antigens, immature forms induce more anti-carbohydrate antibodies than adults. This is the reason for the lower ODs of the anti-immature sera against purified antigens, since these latter antigens essentially react with anti-peptide antibodies (hence, increasing the specificity and sensitivity of the serology). The N-terminus of the 260 kDa antigen shows 80-90% similarity with the hemoglobin alpha-chain of many mammals. The antigens of O. moubata are proteins that are very different from one another and are, therefore, readily purified by ion exchange chromatography. The 20A1 antigen appears to be the most immunogenic and is recognized equally by anti-immature and anti-adult sera. This antigen does not give false positive reactions with the negative control sera analyzed and its N-terminus region shares 46.2% homology with the alpha-chain of the C3 component of rabbit complement.

Host immune response evasion strategies in Ornithodoros erraticus and O. moubata and their relationship to the development of an antiargasid vaccine.

We analysed in mice why the salivary gland extract (SGE-2) from Ornithodoros erraticus and O. moubata induce a protective response with Freund's adjuvants (FAs) in swine while the saliva, in natural conditions, does not. Such protection has been ascribed to the fact that administration of SGE-2 plus FAs permits the recognition of certain salivary components that under natural conditions are not immunogenic. The present findings confirm this hypothesis since in mice, which are unable to recognize the above components, the SGE-2-FAs do not induce any protection. We rule out the possibility that the cause of this could lie in the absence of prostaglandin E2 in the SGE-2 (vs saliva) since it is not present in either fluid. Neither could it be due to a change in antibody isotype since those induced by parasites bites and by the SGE-2-FAs are the same (IgG2a > IgG1 > IgG2b; not IgG3, IgM, IgE). No IgG2a were seen when the SGE-2 were administered alone or with alum or ricin. It is therefore suggested that first responses would be Th1 and the second ones Th2, although no IgE is seen in the latter responses either. The parasites do not require complement to feed; by contrast, they block its activation and skin cellular infiltrates, such as those elicited by IL-8, MCP-1 and C5a, do not affect them, regardless of the presence or not of antitick antibodies.