A Monoclonal Antibody for Malaria Prevention.

BACKGROUND: Additional interventions are needed to reduce the morbidity and mortality caused by malaria. METHODS: We conducted a two-part, phase 1 clinical trial to assess the safety and pharmacokinetics of CIS43LS, an antimalarial monoclonal antibody with an extended half-life, and its efficacy against infection with Plasmodium falciparum. Part A of the trial assessed the safety, initial side-effect profile, and pharmacokinetics of CIS43LS in healthy adults who had never had malaria. Participants received CIS43LS subcutaneously or intravenously at one of three escalating dose levels. A subgroup of participants from Part A continued to Part B, and some received a second CIS43LS infusion. Additional participants were enrolled in Part B and received CIS43LS intravenously. To assess the protective efficacy of CIS43LS, some participants underwent controlled human malaria infection in which they were exposed to mosquitoes carrying P. falciparum sporozoites 4 to 36 weeks after administration of CIS43LS. RESULTS: A total of 25 participants received CIS43LS at a dose of 5 mg per kilogram of body weight, 20 mg per kilogram, or 40 mg per kilogram, and 4 of the 25 participants received a second dose (20 mg per kilogram regardless of initial dose). No safety concerns were identified. We observed dose-dependent increases in CIS43LS serum concentrations, with a half-life of 56 days. None of the 9 participants who received CIS43LS, as compared with 5 of 6 control participants who did not receive CIS43LS, had parasitemia according to polymerase-chain-reaction testing through 21 days after controlled human malaria infection. Two participants who received 40 mg per kilogram of CIS43LS and underwent controlled human malaria infection approximately 36 weeks later had no parasitemia, with serum concentrations of CIS43LS of 46 and 57 µg per milliliter at the time of controlled human malaria infection. CONCLUSIONS: Among adults who had never had malaria infection or vaccination, administration of the long-acting monoclonal antibody CIS43LS prevented malaria after controlled infection. (Funded by the National Institute of Allergy and Infectious Diseases; VRC 612 ClinicalTrials.gov number, NCT04206332.).

Inositol Polyphosphate-5-Phosphatase K (Inpp5k) Enhances Sprouting of Corticospinal Tract Axons after CNS Trauma.

Failure of CNS neurons to mount a significant growth response after trauma contributes to chronic functional deficits after spinal cord injury. Activator and repressor screening of embryonic cortical neurons and retinal ganglion cells in vitro and transcriptional profiling of developing CNS neurons harvested in vivo have identified several candidates that stimulate robust axon growth in vitro and in vivo Building on these studies, we sought to identify novel axon growth activators induced in the complex adult CNS environment in vivo We transcriptionally profiled intact sprouting adult corticospinal neurons (CSNs) after contralateral pyramidotomy (PyX) in nogo receptor-1 knock-out mice and found that intact CSNs were enriched in genes in the 3-phosphoinositide degradation pathway, including six 5-phosphatases. We explored whether inositol polyphosphate-5-phosphatase K (Inpp5k) could enhance corticospinal tract (CST) axon growth in preclinical models of acute and chronic CNS trauma. Overexpression of Inpp5k in intact adult CSNs in male and female mice enhanced the sprouting of intact CST terminals after PyX and cortical stroke and sprouting of CST axons after acute and chronic severe thoracic spinal contusion. We show that Inpp5k stimulates axon growth in part by elevating the density of active cofilin in labile growth cones, thus stimulating actin polymerization and enhancing microtubule protrusion into distal filopodia. We identify Inpp5k as a novel CST growth activator capable of driving compensatory axon growth in multiple complex CNS injury environments and underscores the veracity of using in vivo transcriptional screening to identify the next generation of cell-autonomous factors capable of repairing the damaged CNS.SIGNIFICANCE STATEMENT Neurologic recovery is limited after spinal cord injury as CNS neurons are incapable of self-repair post-trauma. In vitro screening strategies exploit the intrinsically high growth capacity of embryonic CNS neurons to identify novel axon growth activators. While promising candidates have been shown to stimulate axon growth in vivo, concomitant functional recovery remains incomplete. We identified Inpp5k as a novel axon growth activator using transcriptional profiling of intact adult corticospinal tract (CST) neurons that had initiated a growth response after pyramidotomy in plasticity sensitized nogo receptor-1-null mice. Here, we show that Inpp5k overexpression can stimulate CST axon growth after pyramidotomy, stroke, and acute and chronic contusion injuries. These data support in vivo screening approaches to identify novel axon growth activators.

Semi-Field Evaluation of Metofluthrin-Impregnated Nets on Host-Seeking Aedes aegypti and Anopheles dirus.

The efficacy of a metofluthrin-impregnated net (MIN) known as the "Mushikonazu" on the house entry behavior of female Aedes aegypti and Anopheles dirus mosquitoes was evaluated using a semi-field 50-m tunnel setup. While the MIN is labeled for the control of chironomids and moth flies, this study determined the feasibility of using the device, given its current construction and metofluthrin formulation, as a spatial repellent against mosquitoes. Sentinel and cone bioassays were used to determine the insecticidal effect of the MIN. A spatial activity index (SAI) was calculated to evaluate responses of the mosquitoes. For the spatial repellent evaluation against Ae. aegypti, the overall mean of SAI was slightly less than 0 at wk 1 after the MIN application and then decreased for the last 4 wk showing a preference to treatment tent. For An. dirus, the mean SAI at wk 1 was positive, indicating a presumed repellent effect of the MIN against An. dirus. For the subsequent 4 wk, the SAI was negative, indicating a preference for the MIN. Results suggested that the MIN may not be a promising approach to repel Ae. aegypti and An. dirus under field conditions in Thailand. However, it remains probable that the MIN may be effective as a spatial repellent if modifications are made to the metofluthrin concentration or formulation and/or the construction of the device.

Development and evaluation of a pyriproxyfen-treated device to control the dengue vector, Aedes aegypti (L.) (Diptera:Culicidae).

The resurgence of dengue fever and the chikungunya epidemic make the control of Aedes aegypti mosquitoes, the vectors of these diseases, critically important. We developed and evaluated an Ae. aegypti control device that is visually-attractive to mosquitoes. This pyriproxyfen-treated device was evaluated for its impact on Ae. aegypti egg production and population dynamics in dengue-endemic areas in Thailand. The device consists of a "high rise" shaped ovitrap/ resting station covered with black cotton cloth. The device is easily collapsible and transportable. Ae. aegypti are generally drawn towards darker, shadier areas making this device physically attractive as a resting station to mosquitoes of all physiological stages. The results show this device suppressed Ae. aegypti populations after it was introduced into a village. The observed effect was primarily the result of the Ae. aegypti exposure to pyriproxyfen shortly after adult emergence or after taking a blood meal resulting in decreased egg production. We believe the device may be further improved physically and the formulation should be replaced to provide even better efficacy for controlling Ae. aegypti mosquito, populations.

Emergence of Japanese encephalitis virus genotype V in the Republic of Korea.

BACKGROUND: Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of Culex tritaeniorhynchus and 1 pool of Cx. bitaeniorhynchus) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 2010. FINDINGS: Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of Culex tritaeniorhynchus and one pool of Cx. bitaeniorhynchus were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from Cx. bitaeniorhynchus showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952. CONCLUSION: This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in Cx. bitaeniorhynchus, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies.

Japanese encephalitis virus in culicine mosquitoes (Diptera: Culicidae) collected at Daeseongdong, a village in the demilitarized zone of the Republic of Korea.

In total, 22,846 (17,793 culicines and 5,053 Anopheles spp.) female mosquitoes were captured by a Mosquito Magnet trap at Daeseongdong, a small village adjacent to the military demarcation line (center of the demilitarized zone) in northern Gyeonggi Province, Republic of Korea (ROK). Culicine mosquitoes were identified to species, placed in pools of up to 30 mosquitoes each, and screened for flavivirus using a SYBR Green I-based real-time polymerase chain reaction. In total, 51/660 pools positive for flaviviruses and confirmed by DNA sequencing of the NS5 region, were positive for Japanese encephalitis virus (family Flaviviridae, genus Flavivirus, JEV) (50 Culex tritaeniorhynchus Giles and one Culex bitaeniorhynchus Giles). The JEV maximum likelihood estimations (MLEs) (estimated number of viral RNA-positive mosquitoes per 1,000) for Cx. tritaeniorhynchus and Cx. bitaeniorhynchus were 9.7 and 0.9, respectively. This is the first report of a Cx. bitaeniorhynchus positive for JEV in the ROK. JEV is a local civilian and military health threat and a significant concern for nonimmune (unvaccinated) U.S. soldiers, civilians, and family members deployed to the ROK.

Field evaluation of two commercial mosquito traps baited with different attractants and colored lights for malaria vector surveillance in Thailand.

BACKGROUND: Sampling for adult mosquito populations is a means of evaluating the efficacy of vector control operations. The goal of this study was to evaluate and identify the most efficacious mosquito traps and combinations of attractants for malaria vector surveillance along the Thai-Myanmar border. METHODS: In the first part of the study, the BG-Sentinel™ Trap (BGS Trap) and Centers for Disease Control and Prevention miniature light trap (CDC LT) baited with different attractants (BG-lure® and CO2) were evaluated using a Latin square experimental design. The six configurations were BGS Trap with BG-lure, BGS Trap with BG-lure plus CO2, BGS Trap with CO2, CDC LT with BG-lure, CDC LT with BG lure plus CO2, and CDC LT with CO2. The second half of the study evaluated the impact of light color on malaria vector collections. Colors included the incandescent bulb, ultraviolet (UV) light-emitting diode (LED), green light stick, red light stick, green LED, and red LED. RESULTS: A total of 8638 mosquitoes consisting of 42 species were captured over 708 trap-nights. The trap types, attractants, and colored lights affected numbers of female anopheline and Anopheles minimus collected (GLM, P < 0.01). Results revealed that BGS Trap captured many anophelines but was significantly less than the CDC LT. The CDC LT, when baited with BG-lure plus CO2 captured the greatest number of anopheline females with a catch rate significantly higher than the CDC LT baited with BG-lure or CO2 alone (P < 0.05). The number of anopheline females collected from the CDC LT baited with CO2 was greater than the CDC LT baited with BG-lure (646 vs 409 females). None of the alternative lights evaluated exceeded the performance of the incandescent light bulb in terms of the numbers of anopheline and An. minimus collected. CONCLUSION: We conclude that the CDC LT augmented with an incandescent light shows high potential for malaria vector surveillance when baited with CO2 and the BG-lure in combination and can be effectively used as the new gold standard technique for collecting malaria vectors in Thailand.

Molecular detection and identification of Bartonella species in rat fleas from northeastern Thailand.

The presence of Bartonella species in Xenopsylla cheopis fleas collected from Rattus spp. (R. exulans, R. norvegicus, and R. rattus) in Khon Kaen Province, Thailand was investigated. One hundred ninety-three fleas obtained from 62 rats, were screened by polymerase chain reaction using primers specific for the 16S-23S intergenic spacer region, and the presence of Bartonella DNA was confirmed by using the citrate synthase gene. Bartonella DNA was detected in 59.1% (114 of 193) of fleas examined. Sequencing demonstrated the presence of Bartonella spp. similar to B. elizabethae, B. rattimassiliensis, B. rochalimae, and B. tribocorum in the samples tested with a cutoff for sequence similarity ≥ 96% and 4 clustered together with the closest match with B. grahamii (95.5% identity). If X. cheopis proves to be a competent vector of these species, our results suggest that humans and animals residing in this area may be at risk for infection by several zoonotic Bartonella species.

Maintenance of mosquito vectors: effects of blood source on feeding, survival, fecundity, and egg hatching rates.

Artificial membrane-feeding techniques have replaced direct feeding on animals for the maintenance of malaria and arbovirus vectors in many laboratories. Membrane feeding facilitates controlled experimentation of pathogen transmission during mosquito feeding. Sheep blood is commonly used due to its availability and low cost. We evaluated the impact of blood source (human, guinea pig, sheep, and hamster via direct feeding) on feeding rates, adult survival, fecundity, hatching rates, and developmental times for five species of laboratory-colonized mosquitoes (Anopheles dirus, An. cracens, An. minimus, An. sawadwongporni, and Ae. aegypti). We found that feeding rates differ among blood sources within mosquito species. Survival, fecundity, and hatching rates were lower in all Anopheles species and Ae. aegypti after membrane feeding on sheep blood. Survival rates seven days post-feeding on sheep blood were significantly lower (P<0.05) for An. dirus (84.2%), An. minimus (67.2%), An. sawadwongporni (51.5%), and An. cracens (35.5%) relative to other blood sources. An. minimus and An. sawadwongporni laid no eggs by seven days post-feeding with sheep blood, while An. dirus and An. cracens produced significantly fewer numbers of eggs and demonstrated significantly lower hatching rates relative to what was observed with the other blood sources. These findings support the conclusion that sheep blood is not a suitable blood source for laboratory rearing of Anopheles spp.

Operational vector-borne disease surveillance and control: closing the capabilities gap through research at overseas military laboratories.

Malaria, dengue fever, chikungunya virus, leishmaniasis, and a myriad of other vector-borne diseases pose significant threats to the warfighter and to the overall combat effectiveness of units. Military preventive medicine (PM) assets must accurately evaluate the vector-borne disease threat and then implement and/or advise the commander on countermeasures to reduce a particular threat. The success of these measures is contingent upon the biology of the disease vector and on the tools or methods used to conduct vector/pathogen surveillance and vector control. There is a significant gap between the tools available and those required for operational PM assets to provide real-time, effective surveillance and control. A network of US Army and US Navy overseas laboratories is focused on closing the current capabilities gap. Their mission is to develop and field test tools and methods to enhance the combatant commander's ability to identify and mitigate the threat posed by these vector-borne diseases.