Dengue Virus Envelope Dimer Epitope Monoclonal Antibodies Isolated from Dengue Patients Are Protective against Zika Virus.

UNLABELLED: Zika virus (ZIKV) is a mosquito-borne flavivirus responsible for thousands of cases of severe fetal malformations and neurological disease since its introduction to Brazil in 2013. Antibodies to flaviviruses can be protective, resulting in lifelong immunity to reinfection by homologous virus. However, cross-reactive antibodies can complicate flavivirus diagnostics and promote more severe disease, as noted after serial dengue virus (DENV) infections. The endemic circulation of DENV in South America and elsewhere raises concerns that preexisting flavivirus immunity may modulate ZIKV disease and transmission potential. Here, we report on the ability of human monoclonal antibodies and immune sera derived from dengue patients to neutralize contemporary epidemic ZIKV strains. We demonstrate that a class of human monoclonal antibodies isolated from DENV patients neutralizes ZIKV in cell culture and is protective in a lethal murine model. We also tested a large panel of convalescent-phase immune sera from humans exposed to primary and repeat DENV infection. Although ZIKV is most closely related to DENV compared to other human-pathogenic flaviviruses, most DENV immune sera (73%) failed to neutralize ZIKV, while others had low (50% effective concentration [EC50], <1:100 serum dilution; 18%) or moderate to high (EC50, >1:100 serum dilution; 9%) levels of cross-neutralizing antibodies. Our results establish that ZIKV and DENV share epitopes that are targeted by neutralizing, protective human antibodies. The availability of potently neutralizing human monoclonal antibodies provides an immunotherapeutic approach to control life-threatening ZIKV infection and also points to the possibility of repurposing DENV vaccines to induce cross-protective immunity to ZIKV. IMPORTANCE: ZIKV is an emerging arbovirus that has been associated with severe neurological birth defects and fetal loss in pregnant women and Guillain-Barré syndrome in adults. Currently, there is no vaccine or therapeutic for ZIKV. The identification of a class of antibodies (envelope dimer epitope 1 [EDE1]) that potently neutralizes ZIKV in addition to all four DENV serotypes points to a potential immunotherapeutic to combat ZIKV. This is especially salient given the precedent of antibody therapy to treat pregnant women infected with other viruses associated with microcephaly, such as cytomegalovirus and rubella virus. Furthermore, the identification of a functionally conserved epitope between ZIKV and DENV raises the possibility that a vaccine may be able to elicit neutralizing antibodies against both viruses.

A new quaternary structure epitope on dengue virus serotype 2 is the target of durable type-specific neutralizing antibodies.

UNLABELLED: Dengue virus serotype 2 (DENV2) is widespread and responsible for severe epidemics. While primary DENV2 infections stimulate serotype-specific protective responses, a leading vaccine failed to induce a similar protective response. Using human monoclonal antibodies (hMAbs) isolated from dengue cases and structure-guided design of a chimeric DENV, here we describe the major site on the DENV2 envelope (E) protein targeted by neutralizing antibodies. DENV2-specific neutralizing hMAb 2D22 binds to a quaternary structure epitope. We engineered and recovered a recombinant DENV4 that displayed the 2D22 epitope. DENV2 neutralizing antibodies in people exposed to infection or a live vaccine tracked with the 2D22 epitope on the DENV4/2 chimera. The chimera remained sensitive to DENV4 antibodies, indicating that the major neutralizing epitopes on DENV2 and -4 are at different sites. The ability to transplant a complex epitope between DENV serotypes demonstrates a hitherto underappreciated structural flexibility in flaviviruses, which could be harnessed to develop new vaccines and diagnostics. IMPORTANCE: Dengue virus causes fever and dengue hemorrhagic fever. Dengue serotype 2 (DENV2) is widespread and frequently responsible for severe epidemics. Natural DENV2 infections stimulate serotype-specific neutralizing antibodies, but a leading DENV vaccine did not induce a similar protective response. While groups have identified epitopes of single monoclonal antibodies (MAbs), the molecular basis of DENV2 neutralization by polyclonal human immune sera is unknown. Using a recombinant DENV displaying serotype 2 epitopes, here we map the main target of DENV2 polyclonal neutralizing antibodies induced by natural infection and a live DENV2 vaccine candidate. Proper display of the epitope required the assembly of viral envelope proteins into higher-order structures present on intact virions. Despite the complexity of the epitope, it was possible to transplant the epitope between DENV serotypes. Our findings have immediate implications for evaluating dengue vaccines in the pipeline as well as designing next-generation vaccines.

Sonographic detection, evaluation and aspiration of infected acromioclavicular joints.

OBJECTIVE: To describe the sonographic findings of septic arthritis of the acromioclavicular joint. DESIGN AND PATIENTS: A retrospective study of five male patients was carried out. Four of the patients were referred because of signs and symptoms suggestive of glenohumeral joint septic arthritis, one for signs and symptoms suggestive of septic arthritis of the acromioclavicular joint. All the acromioclavicular joints were evaluated with ultrasound, aspirated and the aspirate cultured. RESULTS: All patients had normal ultrasound findings of their glenohumeral joints and distended acromioclavicular joints as determined by ultrasound. Ultrasound examination elicited focal tenderness over the acromioclavicular joint. Aspirates of each acromioclavicular joint grew pyogenic organisms. CONCLUSION: Infection in the acromioclavicular joint is uncommon, but is seen in increased frequency in immune-compromised patients and intravenous drug users. A normal glenohumeral joint on ultrasound in a patient suspected of having a septic shoulder should prompt careful review of the acromioclavicular joint. Aspiration of the acromioclavicular joint is easily performed under ultrasound guidance.

Two possible determinants of the timing of daily episodes of behavior in rats.

The present experiment examined endogenous ultradian rhythms and regulatory metabolic processes as two potential determinants of daily out-of-nest episodes (ONEs) and feeding episodes (FEs) in rats living in a 24-h environment. Two types of photoperiod were used: a Standard 12:12 h L/D schedule and a Skeleton 12:12 h schedule. During each type of photoperiod rats were exposed to 4 feeding conditions of 7 to 12 days each: (a) a baseline of ad lib food and water; (b) restricted to the diurnal (inactive) portion of the cycle; (c) both food and water restricted to the inactive period; and (d) return to baseline. Time series analyses of nocturnal ONEs in baseline revealed a strong circadian rhythm and weaker ultradian rhythms with periods between 2 and 6 h. Analyses of FEs, though, revealed a general absence of circadian rhythms but strong ultradian rhythms with periods similar to those observed in ONEs. When food and water were restricted to the inactive part of the cycle, ONEs showed no change in frequency, but a decrease in average duration and changes in ultradian periodicities. The results indicated control of daily episodes of behavior in rats by ultradian oscillators that are weaker and more variable in affect than those found in voles, but similar in period.

Environmental enrichment: the influences of restricted daily exposure and subsequent exposure to uncontrollable stress.

Environmental enrichment has been proposed to enhance an animal's subsequent ability to learn. While this proposal has received considerable support from experiments involving maze tasks, it has received equivocal support from experiments employing operant and pavlovian tasks. The purpose of the present study is two-fold. The first is to demonstrate that a regimen of restricted daily exposure to environmental enrichment is capable of producing effects similar to those using more standard exposure regimens when compared to the most appropriate control, a group given social exposure. The second is to examine the proposed learning enhancement of environmental enrichment on an operant task both before and following exposure to uncontrollable stress. Uncontrollable stress, as interpreted by learned-helplessness theory, results in the formation of an expectancy of response-reinforcer independence which proactively interferes with the subsequent acquisition of response-outcome associations. It may be possible, then, that environmental enrichment and uncontrollable stress may interact in such a way as to allow the potential learning effects of environmental enrichment to be assessed on an operant task. Rats were exposed to differential environments; one group exposed to an enriched environment and another exposed to a social environment 2 hours daily for 30 days. Each group was then tested on the object-exploration test. Following the acquisition of an appetitive-operant response, a subset of these two groups was exposed to either controllable, uncontrollable, or no stress using parameters known to induce learned helplessness. Animals were then tested on an appetitive-noncontingent test. It was found that, while the enrichment procedure was effective in producing effects on the object-exploration test, environmental enrichment did not modify the acquisition of the operant or the effect produced by uncontrollable stress on the appetitive-noncontingent test.

Restricted daily exposure to environmental enrichment increases the diversity of exploration.

The temporal parameters of environmental enrichment have been examined in two ways. The first is by limiting the total duration of environmental exposure. The effects of this procedure are well documented for both physiology and behavior. The second method is by restricting the daily exposure to environmental enrichment while keeping the days of exposure constant. The physiological effects of this procedure have been documented, but the behavioral effects which have been observed are equivocal. The purpose of the present study was to address this issue. Male rats were individually housed at 44 days of age. They were then randomly assigned to either an enriched environment or an impoverished environment. The enriched animals (EC) were exposed to the enriched environment for 2 hours daily for 30 days while the impoverished animals (IC) were handled daily but not exposed to the enriched environment. Animals were then tested on an object exploration test. The results indicate that 2 hours of daily environmental exposure is sufficient to produce object exploration effects similar to those produced by 24 hours of daily environmental exposure.

Prior exposure to stress reduces the diversity of exploratory behavior of novel objects in the rat (Rattus norvegicus).

Although a large literature has documented the varied effects of stress on an organism, relatively little attention has been devoted to investigating stress effects in ecologically relevant situations. Our experiment was conducted to assess the effects of stress on rats' (Rattus norvegicus) exploration of novel objects in a seminaturalistic and familiar environment that is relatively free of the constraints that have been placed on rats in prior investigations of stress. The results show that prior exposure to stress decreased the rats' diversity of exploration but did not affect general activity in comparison with animals not exposed to stress. We propose that the effect of stress on the qualitative aspects of exploratory behavior may be due to effects on organisms' sensitivity to predation.

Functional and morphologic considerations of the articular eminence.

A study of the angulation of the posterior slope of the articular eminence as determined mechanically and from cephlometric radiographs shows a close correlation.

Enzymatic analysis of total- and HDL-cholesterol: comparison with the standardized Liebermann-Burchard method used by the Lipid Research Clinics program.

We compared two enzymatic cholesterol methods with the standardized chemical method used in the Lipid Research Clinic's (LRC) program. The methods were used to measure total cholesterol and high density lipoprotein (HDL) cholesterol in heparin-MnCl2 supernatants of 1,812 sera collected over a 16-mth period from subjects who were sampled as part of the Hispanic Health and Nutrition Examination Survey. Thirty percent of the subjects had fasted for 12 h or more before venepuncture. The enzymatic total cholesterol values were 1.4-1.8% lower than the LRC method and both enzymatic methods correlated highly with the LRC method (r greater than 0.97). The enzymatic HDL cholesterol values were 2.4 and 6.4% higher than the LRC method, and the correlation between the enzymatic and LRC methods was greater than 0.93. The differences between the enzymatic and LRC methods were the same in samples from fasting and non-fasting subjects.

Multicentric reticulohistiocytosis: assessment of pulmonary disease by gallium-67 scintigraphy.

We present a case of multicentric reticulohistiocytosis with pulmonary involvement. Scintigraphic evaluation with gallium-67 citrate demonstrated bilateral hilar uptake on 2 occasions. Possible mechanisms for gallium avidity are discussed. Gallium scintigraphy has a potential role for assessing systemic involvement in this disease.

Comparison of sodium bicarbonate with dichloroacetate treatment of hyperlactatemia and lactic acidosis in the ischemic rat.

Serum lactic acidosis is characterized by a pH less than 7.25 and lactate greater than 5 mEq. Although sodium bicarbonate (NaHCO3) is standard treatment for this condition, clinical and experimental studies suggest that high doses of NaHCO3 may be ineffectual or even detrimental to brain, cardiovascular, and respiratory function, as well as survival. For this reason, low dose therapy with NaHCO3 has been recommended. Sodium dichloroacetate (NaDCA) has been used successfully to treat clinical and experimentally-induced lactic acidosis. The present study was designed to compare the effects of low dose NaHCO3 with NaDCA on blood pressure, blood chemistries and brain metabolites in rats with a low flow-induced (Type A, the most common type) lactic acidosis. Fasted male Wistar rats were subjected to cerebral ischemia and systemic hypotension for 30 min at which time, if the pH or HCO-3 fell to 7.2 or 10, respectively, the rat was treated with NaHCO3, NaDCA, or an equal volume of sterile water. Over the 30 min of recirculation that followed ischemia, treatment had no effect on blood pressure or glucose or on brain glucose or glycogen. NaHCO3 had no effect on lactate but appeared to stabilize pH and increase HCO3- more than in sham- or NaDCA-treated rats. Although NaDCA caused a greater increase in HCO3- than sham treatment, pH continued to decline. However, lactate decreased more in NaDCA- than in sham- or NaHCO3- treated rats. These results suggest that low dose NaHCO3 is not detrimental in this model; however, although NaHCO3 stabilized pH, it did not rapidly correct the acidosis. NaDCA at this dose had no effect on the acidosis but was effective in decreasing lactate. Since serum lactate has previously correlated with survival and since higher doses of NaDCA have corrected lactic acidosis in other studies, future evaluation of postischemic treatment with higher doses of NaDCA is warranted.