Differences in the Transmissibility of Two Anaplasma phagocytophilum Strains by the North American Tick Vector Species, Ixodes Pacificus and Ixodes Scapularis (Acari: Ixodidae)

The etiologic agent of granulocytic anaplasmosis, Anaplasma phagocytophilum, has a circum-global distribution within the northern hemisphere and shows a host species predilection that varies by the geographic region in which the disease is found. Adaptation by the bacterium to a host species potentially contributes to the variation found worldwide but this is confounded by the bacterium's relationship with its tick vectors, all of which belong to the Ixodes ricinus group. We tested the hypothesis that tick vector species collected from geographic regions sympatric with particular A. phagocytophilum strains will show evidence of a higher degree of vector competence than will tick species and allopatric A. phagocytophilum strains. A reciprocal cross-transmission experiment was performed using an eastern and a western North American strain of A. phagocytophilum (Webster and MRK, respectively) and the two tick species, I. scapularis and I. pacificus, most commonly associated with human and animal transmission of the bacteria in the United States. The western tick, I. pacificus, showed a significantly higher vector competence for A. phagocytophilum than I. scapularis and the eastern isolate, Webster, was more transmissible than its western counterpart, MRK. These results indicate that geographic variation in host susceptibility to A. phagocytophilum strains may play a more important role in the epidemiology of granulocytic anaplasmosis than does the competence of its tick vectors to transmit the pathogen.     

Co-phylogenetic analysis of Anaplasma phagocytophilum and its vectors, Ixodes spp. ticks

The coevolutionary history of Ixodes spp. ticks, the obligately tick-transmitted bacterial pathogen Anaplasma phagocytophilum, and its various rodent reservoir hosts world-wide is not known. According to coevolution theory, the most recently evolved of tick-bacterial complexes could have difficulty maintaining A. phagocytophilum in nature, because transmissibility has not been efficiently maximized. This study was intended to examine the phylogeographic history of I. ricinus-subgroup ticks and A. phagocytophilum, provide an estimate for the date of the divergence of A. marginale and A. phagocytophilum, and evaluate whether there is correspondence between tick and Anaplasma spp. trees. Analysis of Ixodes spp. ticks showed a New World clade consisting of I. scapularis and I. pacificus, European I. ricinus as a sister group to this clade, and Asian I. persulcatus as basal. Of the three A. phagocytophilum genes evaluated, the most resolution was provided by the ankA gene. ankA sequences formed an Old World clade with eastern North America strains as a sister clade. California strains were highly diverse and did not form a clade. Base substitution rates were very comparable along both A. marginale and A. phagocytophilum lineages. Based on 16S rDNA analysis, maximum and minimum divergence times of A. phagocytophilum and A. marginale were calculated to be 78,296,703 and 43,415,708 years, respectively. If A. phagocytophilum did closely coevolve with specific I. ricinus-subgroup tick species, then A. phagocytophilum strains could have specialized on local tick species and optimized local infectivity in the Old World and eastern US. However, lack of absolute resolution of tick trees and conflicting prevalence data (with low prevalence in Asia and western North America) preclude us from inferring a tight coevolutionary relationship of tick species from this phylogeographic analysis.     

A Finger-Stick Whole-Blood HIV Self-Test as an HIV Screening Tool Adapted to the General Public

Background

In 2013, the French Health Authority approved the use of HIV self-tests in pharmacies for the general public. This screening tool will allow an increase in the number of screenings and a reduction in the delay between infection and diagnosis, thus reducing the risk of further infections. We previously compared 5 HIV-self test candidates (4 oral fluid and one whole blood) and demonstrated that the whole blood HIV test exhibited the optimal level of performance (sensitivity/specificity). We studied the practicability of an easy-to-use finger-stick whole blood HIV self-test “autotest VIH^®”, when used in the general public.

Methods and Materials

This multicenter cross-sectional study involved 411 participants from the Parisian region (AIDES and HF association) between April and July 2014 and was divided into 2 separate studies: one evaluating the capability of participants to obtain an interpretable result using only the information notice, and a second evaluating the interpretation of test results, using a provided chart.

Results

A total of 411 consenting participants, 264 in the first study and 147 in the second, were included. All participants were over 18 years of age. In the first study, 99.2% of the 264 participants correctly administered the auto-test, and 21.2% needed, upon their request, telephone assistance. Ninety-two percent of participants responded that the test was easy/very easy to perform, and 93.5% did not find any difficulty obtaining a sufficient good quantity of blood. In the second study, 98.1% of the 147 participants correctly interpreted the results. The reading/interpretation errors concerned the negative (2.1%) or the indeterminate (3.3%) auto-tests.

Conclusions

The success rate of handling and interpretation of this self-test is very satisfactory, demonstrating its potential for use by the general public and its utility to increase the number of opportunities to detect HIV patients.     

Co-infection of Ornithodoros coriaceus with the relapsing fever spirochete, Borrelia coriaceae, and the agent of epizootic bovine abortion

The soft tick, Ornithodoros coriaceus (Koch) (Acari: Argasidae), is a common mammalian parasite of livestock in many arid regions of the western U.S.A. The tick is a known vector of the undescribed bacterial pathogen that causes epizootic bovine abortion (EBA), which results in late-term abortions in beef cattle and subsequent economic loss, which can be considerable, to producers. A second reported bacterial pathogen, Borrelia coriaceae, a member of the relapsing fever complex, has also been identified in this tick and was at one time hypothesized to be the aetiological agent of EBA. In order to test whether bacterial infections in ticks overlapped geographically and to determine the prevalence of co-infection in O. coriaceus populations, we used molecular methods to detect bacterial DNA from ticks collected from a wide variety of habitats in California, Nevada and Oregon. Of the 15 sites at which ticks tested positive for the agent of EBA (aoEBA), eight also contained ticks positive for Borrelia spp. by polymerase chain reaction assay. Additionally, two ticks were co-infected; both of these were collected from the same location. Univariate risk analysis indicated the presence of juniper-dominated habitat at the collection site and geographic location to be significantly associated with infection of the tick vector by either pathogen.     

PERMANENT GENETIC RESOURCES: Identification and characterization of 14 polymorphic microsatellite loci in the argasid tick Ornithodoros coriaceus

Fourteen polymorphic microsatellite loci (di, tetra and di‐tetra complexes) were developed for the argasid tick Ornithodoros coriaceus. Polymorphism was assessed for 56 individuals from two populations separated by ~95 km. All loci were polymorphic (X = 7, range 3–17 alleles). All loci were in Hardy–Weinberg equilibrium except for one locus (OrC 8) in a single population (P < 0.00119, after Bonferroni correction for multiple tests).     

Use of an exotic host plant shifts immunity,chemical defense,and viral burden in wild populations of a specialist insect herbivore

Defense against natural enemies constitutes an important driver of herbivore host range evolution in the wild. Populations of the Baltimore checkerspot butterfly, Euphydryas phaeton (Nymphalidae), have recently incorporated an exotic plant, Plantago lanceolata (Plantaginaceae), into their dietary range. To understand the tritrophic consequences of utilizing this exotic host plant, we examined immune performance, chemical defense, and interactions with a natural entomopathogen (Junonia coenia densovirus, Parvoviridae) across wild populations of this specialist herbivore. We measured three immune parameters, sequestration of defensive iridoid glycosides (IGs), and viral infection load in field‐collected caterpillars using either P. lanceolata or a native plant, Chelone glabra (Plantaginaceae). We found that larvae using the exotic plant exhibited reduced immunocompetence, compositional differences in IG sequestration, and higher in situ viral burdens compared to those using the native plant. On both host plants, high IG sequestration was associated with reduced hemocyte concentration in the larval hemolymph, providing the first evidence of incompatibility between sequestered chemical defenses and the immune response (i.e., the “vulnerable host” hypothesis) from a field‐based study. However, despite this negative relationship between IG sequestration and cellular immunity, caterpillars with greater sequestration harbored lower viral loads. While survival of virus‐infected individuals decreased with increasing viral burden, it ultimately did not differ between the exotic and native plants. These results provide evidence that: (1) phytochemical sequestration may contribute to defense against pathogens even when immunity is compromised and (2) herbivore persistence on exotic plant species may be facilitated by sequestration and its role in defense against natural enemies.     

High prevalence of cytomegalovirus (CMV) infection in infants born to HIV infected mothers–ANRS French Perinatal Cohort (EPF)

Whenever there is a sensational criminal case involving HIV transmission, the media cover it with far more gusto than they usually devote to scientific advances in the field. For example, a murder trial is now taking place in Canada involving a man who has been accused of sexually transmitting HIV to 11 different women, two of whom have died of their infections. Moreover, it is alleged that the accused perpetrator deliberately withheld from these women the fact that he was HIV-positive and that he refused to use a condom during intercourse. Notwithstanding that the suspect is possibly psychopathic and uncaring, or possibly of low intelligence and unable to assess the consequence of his actions, most people probably hope that he is convicted, sentenced, and imprisoned for his acts. Furthermore, most people probably wish for the criminal justice system to pursue these cases with vigour. In fact, however, people should understand that such legal action, and the willingness of the courts to hear these cases, will only weaken the global battle against HIV transmission.     

Use of an exotic host plant reduces viral burden in a native insect herbivore

Incorporation of exotic plants into the diets of native herbivores is a common phenomenon, influencing interactions with natural enemies and providing insight into the tritrophic costs and benefits of dietary expansion. We evaluated how use of an exotic plant, Plantago lanceolata, impacted immune performance, development and susceptibility to pathogen infection in the neotropical herbivore Anartia jatrophae (Lepidoptera: Nymphalidae). Caterpillars were reared on P. lanceolata or a native plant, Bacopa monnieri, and experimentally infected with a pathogenic virus, Junonia coenia densovirus. We found that virus-challenged herbivores exhibited higher survival rates and lower viral burdens when reared on P. lanceolata compared to B. monnieri, though immune performance and development time were largely similar on the two plants. These findings reveal that use of an exotic plant can impact the vulnerability of a native herbivore to pathogen infection, suggesting diet-mediated protection against disease as a potential mechanism facilitating the incorporation of novel resources.