George B. Schoeler

Decorin-binding protein A (DbpA) of Borrelia burgdorferi is not protective when immunized mice are challenged via tick infestation and correlates with the lack of DbpA expression by B. burgdorferi in ticks.

ABSTRACT Previous studies showed that decorin-binding protein A (DbpA) ofBorrelia burgdorferi was a protective immunogen in the murine model of Lyme borreliosis when mice were challenged (needle inoculated) intradermally with in vitro-cultivated spirochetes. In the present study, DbpA-immunized C3H/HeJ mice were not protected from infection when infested with Ixodes scapularis nymphs harboring virulent B. burgdorferi 297. This lack of protection correlated with the failure to detect DbpA on B. burgdorferi in ticks, suggesting that DbpA is not available as a target for bactericidal antibodies in serum when B. burgdorferi-infected ticks take their blood meal from an immunized host. The failure of DbpA immunization to protect tick-challenged mice contradicts the results of earlier needle inoculation vaccination experiments and suggests that DbpA may not be suitable as a Lyme disease vaccine.

Larval Mosquito Habitat Utilization and Community Dynamics of Aedes albopictus and Aedes japonicus (Diptera: Culicidae)

ABSTRACT Aedes albopictus (Skuse) and Ae. japonicus (Theobald) are important container-inhabiting mosquitoes that transmit disease agents, outcompete native species, and continue to expand their range in the United States. Both species deposit eggs in natural and artificial containers and thrive in peridomestic environments. The goal of our study was to examine the types and characteristics of containers that are most productive for these species in the northeastern United States. In total, 306 containers were sampled in urban, suburban, and rural areas of New Jersey. Multiple biotic and abiotic factors were recorded in an attempt to identify variables associated with the productivity of each species. Based on pupal abundance and density of container types, results showed that tires, trash cans, and planter dishes were the most important containers for Ae. albopictus, while planter dishes were the most important containers for Ae. japonicus. Container color (black and gray), material (rubber), and type (tires) were correlated with species presence for Ae. albopictus and Ae. japonicus. These factors may play a role in the selection of oviposition sites by female mosquitoes or in the survival of their progeny. Differences in species composition and abundance were detected between areas classified as urban, suburban, and rural. In urban and suburban areas, Ae. albopictus was more abundant in container habitats than Ae. japonicus; however, Ae. japonicus was more abundant in rural areas, and when water temperatures were below 14°C Our results suggest many variables can influence the presence of Ae. albopictus and Ae. japonicus in container habitats in northeastern United States.

Natural Plasmodium Infections in Anopheles darlingi and Anopheles benarrochi (Diptera: Culicidae) from Eastern Peru

Abstract Malaria, both Plasmodium falciparum (Welch) and Plasmodium vivax (Grassi & Feletti), has reemerged as a significant public health disease issue in Peru, especially in forested areas in the eastern part of the country. The spread of Anopheles darlingi Root, the principal South American malaria vector, into new areas of Peru is thought to be a factor in this resurgence. However, epidemiological evidence suggests that in malaria endemic areas of eastern Peru where An. darlingi does not occur, other species are involved in malaria transmission. The objective of this study was to analyze Anopheles species collected from 11 provinces within four departments in eastern Peru during 2001 and 2002 for infections with P. falciparum and P. vivax. More than 84,000 Anopheles mosquitoes representing 13 species were tested by enzyme-linked immunosorbent assay for the presence of Plasmodium circumsporozoite (CS) proteins. Of these, only An. darlingi and Anopheles benarrochi Gabaldón, Cova García & López were found positive. In total, 14 (0.98%) of 1,432 pools of An. darlingi were positive for Plasmodium species; specifically 10 (0.70%) pools were positive for P. falciparum, two (0.14%) were positive for P. vivax VK210, and two (0.14%) were positive for P. vivax VK247 proteins. Nine (0.14%) of 6,323 pools of An. benarrochi were positive for Plasmodium; five (0.08%) of 6,323 pools were positive for P. falciparum, two (0.03%) were positive for P. vivax VK247, one (0.02%) was positive for mixed P. vivax VK210/VK247 infections, and one (0.02%) was positive for mixed P. falciparum and P. vivax VK210 CS-proteins. Although infection rates in An. benarrochi were significantly lower (0.14%) than rates found for An. darlingi (0.98%), our data suggest that An. benarrochi may play a role in transmitting and maintaining Plasmodium species in various malaria endemic areas of eastern Peru.

Cytokine responses of C3H/HeN mice infested with Ixodes scapularis or Ixodes pacificus nymphs.

Lyme borreliosis, caused by Borrelia burgdorferi, is transmitted by Ixodes scapularis in the eastern and midwestern United States and by Ixodes pacificus in the far‐Western United States. Studies have shown that infestation with I. scapularis nymphs modulates host cytokine production; however, the influence of I. pacificus infestation on host cytokines remains uninvestigated. This study demonstrated how repeated infestations with pathogen‐free I. scapularis or I. pacificus nymphs affects the production of the macrophage cytokines IL‐1β, IL‐6 and tumour necrosis factor‐α and the T lymphocyte cytokines IL‐2, IL‐4, IL‐5, IL‐6, IL‐10 and IFN‐γ by C3H/HeN mice. Female mice were infested once or twice with pathogen‐free I. scapularis or I. pacificus nymphs, with a 14‐day tick‐free period between exposures. After each infestation, tick biology parameters were assessed and macrophage and T lymphocyte cytokine production measured by antigen capture ELISA. Acquired resistance to tick feeding did not develop after infestation with either tick species. Differences in cytokine production were observed between infested and noninfested mice, and between mice infested with either I. scapularis or I. pacificus nymphs. Infestations polarized cytokine production towards a Th2 cytokine profile, with suppression of pro‐inflammatory Th1 cytokines. This pattern of cytokine production is more pronounced for I. pacificus infested mice.

TAMING A TIGER IN THE CITY: COMPARISON OF MOTORIZED BACKPACK APPLICATIONS AND SOURCE REDUCTION AGAINST THE ASIAN TIGER MOSQUITO, AEDES ALBOPICTUS

Abstract We evaluated 2 strategies to manage Aedes albopictus: 1) motorized backpack applications and 2) source reduction (coupled with hand-applied applications of larvicide). Backpack applications used a water-dispersible granular formulation (VectoBac® WDG) of Bacillus thuringiensis var. israelensis (Bti), whereas source reduction used granular formulations of the insect growth regulator methoprene (Altosid®) combined with a monomolecular film surfactant (Agnique®). Six subplots (total 8.02 ha) were selected for backpack applications, source reduction, and control groups. The experiments were blind with applications conducted randomly and independently. Efficacy was determined through placement of bioassay cups with larvae within experimental plots 1 day before treatment. Backpack applications resulted in 76% (±8.2% SE) and source reduction resulted in 92% (±4.1% SE) larval mortality. Backpack applications required 50 times less labor than source reduction (0.25 versus 0.005 ha/h). The cost of backpack applications, including labor, was

Point-source and area-wide field studies of pyriproxyfen autodissemination against urban container-inhabiting mosquitoes

159.88/ha, compared with

Influence of repeated infestations with pathogen-free Ixodes scapularis (Acari : Ixodidae) on in vitro lymphocyte proliferation responses of C3H/HeN mice

659.65/ha for source reduction. Although overall efficacy was slightly lower, motorized backpack applications of Bti were more efficient and cost-effective than source reduction methods to control Ae. albopictus in urban settings at the community level.

Influence of soluble proteins from the salivary glands of ixodid ticks on the in-vitro proliferative responses of lymphocytes from BALB/c and C3H/HeN mice.

Autodissemination of insecticides is a novel strategy for mosquito management. We tested if contaminated Aedes albopictus (Skuse) mosquitoes from a small area treated with commercial formulations (79gm a.i. pyriproxyfen/ha) using conventional techniques, would disseminate pyriproxyfen over a wider area. Pyriproxyfen showed LC50=0.012 ppb for Ae. albopictus. Direct treatment and autodissemination efficacy was measured as a pupal mortality by conducting Ae. albopictus larval bioassay. A tire pile (n=100 tires) treated by backpack sprayer as a point-source treatment showed higher pupal mortality in 2010 (60.8% for week 0-6) than in 2011 (38.3% for week 0-6). The sentinel containers placed for autodissemination in four compass directions out to 200-400m from the tire pile showed 15.8% pupal mortality (week 1-6) in the first year, and 1.4% pupal mortality in the second year. No significant difference was detected among the distances and direction for pupal mortality. In area-wide treatments, vegetation was sprayed in checkerboard pattern (3.7% of 105ha) using backpack sprayer in 2010 and in strips (24.8% of 94ha) using truck-mounted ultra-low volume (ULV) sprayer in 2011. In both years, the area-wide direct treatment efficacy was lower (30.3% during 2010 and 5.3% in 2011) than point-source treatments. Autodissemination in area-wide plots was higher in 2010 (10.3%) than 2011 (2.9%). However, area-wide treatments were ineffective on field populations of Ae. albopictus as monitored by using BGS traps. We found accumulation of pyriproxyfen in the week 6 autodissemination containers in both experiments. The differences in autodissemination in 2010 and 2011 can be attributed to higher rainfall in the second year that may have eroded the pyriproxyfen from treatment surfaces and sentinel containers. Our study shows that ULV surface treatments of conventional formulation do not work for autodissemination. The effectiveness of pyriproxyfen in autodissemination may be improved by developing specific formulations to treat vegetation and tires that can load high doses on mosquitoes.

Identification and Genomic Analysis of a Novel Group C Orthobunyavirus Isolated from a Mosquito Captured near Iquitos, Peru.

Abstract In the United States, Ixodes scapularis Say has been implicated as the vector of at least three human pathogens. Tick induced modulation of host immunity is increasingly recognized as an important factor in successful transmission or establishment of tick-borne pathogens. This study was conducted to determine the effects of repeated infestations with pathogen-free I. scapularis nymphs on in vitro proliferative responses of splenic lymphocytes from C3H/HeN mice. Lymphocytes from repeatedly infested and uninfested mice were exposed to concanavalin A (Con A), Escherichia coli Castellini & Chalmers lipopolysaccharide (LPS), or I. scapularis salivary gland soluble proteins (SGSP), to determine if lymphocyte responses differed between tick-exposed and nonexposed mice. Female C3H/HeN mice were infested one to four times with pathogen-free I. scapularis nymphs, with a 14-d tick-free period between each exposure. After each infestation, tick biology parameters were measured and lymphocyte proliferative responses assessed. Acquired resistance to I. scapularis was not evident in mice subjected to tick feeding. Significant differences in the responses of lymphocytes exposed to I. scapularis SGSP were observed between infested and noninfested mice. In contrast, few differences between infested and noninfested mice were evident for lymphocytes exposed to Con A or LPS. Our results suggest that repeated exposure to I. scapularis nymphs does not affect Con A or LPS-induced proliferation of splenic lymphocytes, but significantly effects lymphocyte responses to tick salivary gland antigens.

Species Diversity, Seasonal, and Spatial Distribution of Mosquitoes (Diptera: Culicidae) Captured in Aotus Monkey-Baited Traps in a Forested Site Near Iquitos, Peru

In the U.S.A., Borrelia burgdorferi, the causative agent of Lyme borreliosis, is transmitted to humans by the ticks Ixodes scapularis and I. pacificus. Tick modulation of host immunity is an important factor in tick transmission of such pathogens. The proliferative responses of lymphocytes from BALB/c and C3H/HeN mice exposed to the salivary-gland soluble proteins (SGSP) of I. scapularis, I. pacificus or Dermacentor andersoni were therefore compared in vitro. This produced the present report, the first to describe the effects of I. pacificus SGSP on the proliferative responses of a hosts lymphocytes in vitro. The effects of four concentrations of SGSP from each tick species were evaluated with unstimulated, and concanavalin-A-stimulated lymphocytes of each mouse strain. The responses of lymphocytes from both mouse strains were significantly effected when exposed to SGSP derived from each tick species. Responses of the unstimulated lymphocytes to SGSP indicated that the proteins from I. pacificus suppressed in-vitro lymphocyte proliferation to a greater degree than those from the other species investigated. For the concanavalin-A stimulated cells, however, suppression of the proliferative responses was greatest for cells exposed to I. scapularis SGSP.