Safety, immunogenicity, and efficacy of a malaria sporozoite vaccine administered with monophosphoryl lipid A, cell wall skeleton of mycobacteria, and squalane as adjuvant

A Plasmodium falciparum circumsporozoite protein (PfCSP) recombinant fusion protein, R32NS1(81), formulated with monophosphoryl lipid A, cell wall skeleton of mycobacteria, and squalane (Detox) was administered to 12 volunteers. One volunteer had malaise and self-limited painful induration at the injection site after the second dose and declined further immunization. The other 11 volunteers tolerated the three doses of 1,230 micrograms of vaccine, but most complained of sore arms; in five cases the pain or malaise was severe enough to interfere with work or sleep. Two weeks after the third dose of vaccine, four of the 11 immunized volunteers had > or = 14 micrograms/ml of antibodies to the repeat region of the PfCSP in their serum. Two of these four volunteers did not develop P. falciparum parasitemia when challenged by the bite of five mosquitoes carrying P. falciparum sporozoites. The seven volunteers with lower levels of antibodies and 11 of 11 controls developed parasitemia. These data are consistent with other studies, and indicate that vaccine-induced antibodies against the repeat region of PfCSP can prevent effective sporozoite infection of hepatocytes in humans. The challenge is to improve the immunogenicity of PfCSP-based vaccines, and to develop methods for including PfCSP peptides as components of multitarget malaria vaccines.     

Protective oral immunization of chickens against Eimeria tenella with sporozoite surface antigens

Antigens were extracted from the surface of Eimeria tenella sporozoites with a solution containing Triton X 100 (1%), sodium dodecyl sulphate (0.5%) Na deoxycholate (1%) and EDTA (1 mM). After removal of the detergents, these surface antigen preparations conferred an immunity that protected chickens against a subsequent infection (10(4) sporulated oocysts). The best results were obtained after two 250 micrograms injections of Al(OH)3 adsorbed antigens (oocyst output per g caecal material on Day 7 post infection: 2.39 x 10(7) +/- 0.32 x 10(7) oocysts for controls and 7.37 +/- 10(6) +/- 3.19 x 10(6) oocysts for vaccinated birds) and after four gastric intubations of liposome entrapped antigens (oocysts output on Day 7 postinfection: 2.75 x 10(6) +/- 2.02 x 10(6) g-1 caecal material). These results represented respectively 70 and 88% protection indexes. Studies on the systemic and local antibody response after one or several infections of chickens with the parasite indicated at least 20 different molecules in the detergent antigens which are classified after immunoblotting according to their properties.     

Persistence of humoral response against sporozoite and blood-stage malaria antigens 7 years after a brief exposure to Plasmodium vivax

The persistence of malarial antibodies was evaluated in subjects living in a rural community (in Minas Gerais State, Brazil) briefly exposed to a Plasmodium vivax malaria outbreak outside of the area in which malaria was endemic. Transmission was interrupted by treatment of all patients and their relatives and/or neighbors, although the latter had neither symptoms nor blood parasites. Antibodies to P. vivax antigens (recombinant proteins from sporozoites [rPvCS] and from blood stages [rPv200]) were measured in parallel by ELISA with sera collected at two time points after transmission. Anti-rPvCS IgG antibodies were positive in approximately 40% and 20% of the subjects 8 months and 7 years after exposure, respectively. Anti-rPv200 IgG was first detected in 61% of the subjects who had had malarial symptoms and remained positive in 47% after 7 years. Among the prophylactically treated group, anti-rPv200 IgG was detected in only 28% after 8 months. The levels of both antibodies decreased with time in all positive subjects.     

Development of a malaria vaccine

Development of an effective malaria vaccine poses a major scientific challenge both in the laboratory and in the field. Such a vaccine is necessary because of the massive disease burden of malaria in the developing world, the global spread of drug resistance, and the difficulty of sustainable control of the mosquito vector. Animal models have shown the immunological feasibility of vaccines targeted against different stages of parasite development, and studies in human volunteers have shown that a recombinant protein vaccine can protect against challenge with the homologous strain of parasite. However, both natural and vaccine-induced immunity are hampered by the remarkable capacity of the parasites to vary critical antigenic structures; large field trials of a synthetic peptide vaccine gave equivocal results. In an attempt to overcome the dual difficulty of poor immunogenicity and parasite diversity, much experimental work is now focused on complex antigenic constructs, delivered as DNA vaccines or in live vectors such as vaccinia, with multiple targets at each stage of parasite development.     

Boosting with recombinant vaccinia increases immunogenicity and protective efficacy of malaria DNA vaccine

To enhance the efficacy of DNA malaria vaccines, we evaluated the effect on protection of immunizing with various combinations of DNA, recombinant vaccinia virus, and a synthetic peptide. Immunization of BALB/c mice with a plasmid expressing Plasmodium yoelii (Py) circumsporozoite protein (CSP) induces H-2Kd-restricted CD8+ cytotoxic T lymphocyte (CTL) responses and CD8+ T cell- and interferon (IFN)-gamma-dependent protection of mice against challenge with Py sporozoites. Immunization with a multiple antigenic peptide, including the only reported H-2Kd-restricted CD8+ T cell epitope on the PyCSP (PyCSP CTL multiple antigenic peptide) and immunization with recombinant vaccinia expressing the PyCSP induced CTL but only modest to minimal protection. Mice were immunized with PyCSP DNA, PyCSP CTL multiple antigenic peptide, or recombinant vaccinia expressing PyCSP, were boosted 9 wk later with the same immunogen or one of the others, and were challenged. Only mice immunized with DNA and boosted with vaccinia PyCSP (D-V) (11/16: 69%) or DNA (D-D) (7/16: 44%) had greater protection (P < 0. 0007) than controls. D-V mice had significantly higher individual levels of antibodies and class I-restricted CTL activity than did D-D mice; IFN-gamma production by ELIspot also was higher in D-V than in D-D mice. In a second experiment, three different groups of D-V mice each had higher levels of protection than did D-D mice, and IFN-gamma production was significantly greater in D-V than in D-D mice. The observation that priming with PyCSP DNA and boosting with vaccinia-PyCSP is more immunogenic and protective than immunizing with PyCSP DNA alone supports consideration of a similar sequential immunization approach in humans.     

Testosterone impairs efficacy of protective vaccination against P. chabaudi malaria

Vaccination with surface membranes isolated from Plasmodium chabaudi-infected erythrocytes can protect B10.A mice from the lethal outcome of P. chabaudi malaria. However, the efficacy depends on gender and testosterone levels. Thus, vaccination protects over 90% of female mice, but only about 55% of male mice and only about 34% of female mice when pretreated with testosterone for 4 weeks. The suppressive testosterone effect remains imprinted in females even at 10 weeks after the testosterone treatment. These data indicate that not only genetic but also environmental factors restrict the host's immune response to a malaria vaccine.     

Long-term efficacy and immune responses following immunization with the RTS,S malaria vaccine

The malaria sporozoite vaccine candidate RTS,S, formulated with an oil-in-water emulsion plus the immunostimulants monophosphoryl lipid A and the saponin derivative QS21 (vaccine 3), recently showed superior efficacy over two other experimental formulations. Immunized volunteers were followed to determine the duration of protective immune responses. Antibody levels decreased to between one-third and one-half of peak values 6 months after the last dose of vaccine. T cell proliferation and interferon-gamma production in vitro were observed in response to RTS,S or hepatitis B surface antigen. Seven previously protected volunteers received sporozoite challenge, and 2 remained protected (1/1 for vaccine 1, 0/1 for vaccine 2, and 1/5 for vaccine 3). The prepatent period was 10.8 days for the control group and 13.2 days for the vaccinees (P < .01). Immune responses did not correlate with protection. Further optimization in vaccine composition and/or immunization schedule will be required to induce longer-lasting protective immunity.     

Protective immune responses against protease-like antigens of the murine malaria parasite Plasmodium vinckei

The Plasmodium falciparum proteins serine repeat antigen (SERA) and serine repeat protein homologue (SERPH) have similarity in sequence with cysteine proteases in a well-conserved protease domain. We identified three SERA homologues from the murine malaria parasite Plasmodium vinckei and evaluated immune responses to the protease domains of these proteins. Mice that developed protective immunity to P. vinckei after serial infection and cure demonstrated humoral and cell-mediated responses against the SERA homologue protease domains. Mice immunized with Salmonella typhimurium expressing the protease domain of one of these antigens demonstrated cellular responses against the antigen and increased survival against lethal challenge with P. vinckei. Our results suggest that the protease domains of SERA and SERPH are worthy of additional study as potential components of a malaria vaccine.     

Further studies on the efficacy of a live vaccine against mastitis caused by Streptococcus uberis

Three groups of dairy cows were immunized by subcutaneous (s.c.) administration of a preparation of live Streptococcus uberis (strain 0140J) and an intramammary infusion of a soluble surface extract derived from same the bacteria. Animals in Groups 1 and 2 received two s.c. vaccinations plus an intramammary inoculation. Animals in Group 3 received two s.c. vaccinations but did not receive the intramammary infusion. In addition to the vaccinated animals, each group also contained two non-vaccinated (control) animals. All animals were challenged experimentally by intramammary infusion (in two quarters per animal) of ca 100 c.f.u. of S. uberis (strain 0140J or C221) and monitored for clinical signs of disease, bacterial numbers in milk, somatic cell count in milk, and daily milk yield for the following 10 days. Animals in Group I were challenged with strain 0140J. Only one out of six challenged quarters of three vaccinated cows developed clinical disease compared to all (four out of four) quarters of non-vaccinated cows. Animals in Group 2 were challenged with strain C221. All challenged quarters of three vaccinated (six out of six) and two non-vaccinated (four out of four) cows developed clinical mastitis. Animals in Group 3 were challenged with strain 0140J. Five out of eight quarters on four vaccinated cows developed clinical mastitis but the onset was delayed in comparison with that in both non-vaccinated cows in which four out of four challenged quarters developed clinical mastitis. These results indicated that vaccination with live S. uberis protects against challenge with the homologous strain but was less effective against a heterologous strain. Reduced protection was also seen when the intramammary booster was omitted.     

Therapeutic efficacy of clindamycin in combination with quinine for treating uncomplicated malaria in a village dispensary in Gabon

The efficacy of a 3-day clindamycin-quinine regimen to treat clinical malaria attacks was investigated in 256 children from western Gabon. Treatment was well tolerated by all of the children and its efficacy was higher than 97% by day 20. Thus this 3-day clindamycin-quinine regimen might constitute a potential alternative to chloroquine for treating clinical malarial attacks in children from Gabon.     

Protective efficacy of a dengue 2 DNA vaccine in mice and the effect of CpG immuno-stimulatory motifs on antibody responses

A recently described DNA vaccine for dengue (DEN) type 2 was shown to elicit high levels of neutralizing antibodies in mice. The vaccine candidate consists of the PreM and 92% of the envelope genes of DEN 2 New Guinea C strain. We further evaluated this DNA vaccine candidate by examining the effect of immuno-stimulatory CpG DNA motifs on antibody response and by studying the protective efficacy of the vaccine. The results showed that CpG motifs present in pUC 19 significantly improved the antibody response to a suboptimal dose of 3.1 micrograms of the DEN DNA vaccine. In a lethal mouse intracerebral challenge model, the vaccine provided a significant level of protection. Sixty percent of the mice immunized with the DEN DNA vaccine plus pUC 19 survived the challenge compared to only 10% in the control group that received vector plus pUC. These studies illustrate that nucleic acid immunization is a viable approach to developing a DEN vaccine and that immuno-stimulatory CpG DNA motifs can be used to lower the minimum dose required to produce an antibody response.     

Comparative efficacy of experimental anthrax vaccine candidates against inhalation anthrax in rhesus macaques

The authors examined the efficacy of Bacillus anthracis protective antigen (PA) combined with adjuvants as vaccines against an aerosol challenge of virulent anthrax spores in rhesus macaques. Adjuvants tested included i) aluminum hydroxide (Alhydrogel), ii) saponin QS-21 and iii) monophosphoryl lipid A (MPL) in squalene/lecithin/Tween 80 emulsion (SLT). Animals were immunized once with either 50 micrograms of recombinant PA plus adjuvant, or with Anthrax Vaccine Adsorbed (AVA), the licensed human anthrax vaccine. The serological response to PA was measured by enzyme linked immunosorbent assay. Lymphocyte proliferation and serum neutralization of in vitro lethal toxin cytotoxicity were also assayed. In all vaccine groups, anti-PA IgM and IgG titers peaked at 2 weeks and 4-5 weeks postimmunization, respectively. Five weeks postimmunization, animals in all vaccine groups demonstrated PA-specific lymphocyte proliferation and sera that neutralized in vitro cytotoxicity. Six weeks after immunization, the animals were challenged by aerosol with approximately 93 LD50 of virulent anthrax spores. Animals were bled daily for 1 week to monitor bacteremia, and deaths were recorded. Anti-PA ELISA titers in all groups of immunized animals were substantially increased 2 weeks after challenge. One dose of each vaccine provided significant protection (> 90%) against inhalation anthrax in the rhesus macaques.     

Placebo-controlled evaluation of a modified life virus vaccine against feline infectious peritonitis: safety and efficacy under field conditions

A modified live virus vaccine against feline infectious peritonitis (FIP) was evaluated in a double blind, placebo-controlled field trial in two high-risk populations. The vaccine was found to be safe and efficacious in one population of cats that had low antibody titre against feline coronavirus (FCoV) at the time of vaccination. Although clinically healthy at the time of vaccination, retrospectively some vaccinees that later came down with FIP were found to be RT-PCR positive for FCoV in plasma and showed changes in blood parameters consistent with early stage of FIP. It is concluded that vaccination can protect cats with no or low FCoV antibody titres and that in some cats vaccine failure was probably due to pre-existing infection.     

The anti-emetic efficacy of a combination of ondansetron and droperidol

The anti-emetic efficacy of a combination of ondansetron 8 mg with either droperidol 0.75 mg or 1.25 mg given prophylactically was studied in a randomised blinded trial of 94 female inpatients with a previous history of postoperative nausea and vomiting and scheduled to have laparoscopic surgery. A standardised general anaesthetic technique was used for all patients. The mean estimated risk of postoperative sickness according to predictive patient characteristics was 65% for both treatment groups. During the 24 h study period, the proportion of patients with nausea was similar (35%) in both groups, and vomiting occurred in 16% and 14% of the patients in the droperidol 0.75 mg and 1.25 mg groups, respectively. No serious adverse events were observed. Ondansetron in combination with droperidol 0.75 mg resulted in less drowsiness than in combination with 1.25 mg (p = 0.03). In conclusion, a prophylactic combination treatment of ondansetron 8 mg with a small dose of droperidol was clinically effective and well tolerated for the prevention of postoperative nausea and vomiting after laparoscopic surgery in patients with a high probability of nausea and vomiting.     

The vaccine efficacy of native paramyosin (Sj-97) against Chinese Schistosoma japonicum

One of the promising anti-schistosome vaccine candidates currently under investigation is paramyosin, a 97-kDa myofibrillar protein located in the muscles and tegument of schistosome worms. Here we describe the results of two vaccination/challenge experiments undertaken in mice using native paramyosin isolated from adult worms of a Chinese strain of Schistosoma japonicum. In both sets of experiments, a relatively low but consistent and significant reduction in worm burden was evident in mice vaccinated subcutaneously with S. japonicum paramyosin and Freund's adjuvant. In contrast, intraperitoneal vaccination of mice with Chinese strain S. japonicum paramyosin without adjuvant did not result in any reduction in worm numbers when compared with a saline control group. These data contrast with the impressive protection figures reported by another group who used a similar intraperitoneal vaccination protocol with native paramyosin extracted from Philippine strain S. japonicum.     

The efficacy of enterosorption and a combination of antioxidants in schizophrenics

A total of 143 patients with schizophrenia, who ranged from 28 to 42 years old, were studied. Of these, 68 patients were running a continuously progredient course, 75 were in the phase of exacerbation of the attack-like progredient course of schizophrenia. Group I (n = 76) of patients received the enterosorbent polysorb and a complex of antioxidants (tocoferolum acetatum, ascorbic acid, quercetin) as a supplement to the conventional therapy, group II (n = 67) was placed on the conventional therapy only. A complex of the antioxidants as well as the enterosorbent had a positive effect on the clinical course of the condition in 63.2% of group I patients who managed, among other therapeutic benefits, to achieve a stable remission. They have also demonstrated a concomitant improvement or normalization of indices for lipid peroxidation.     

Plasmodium yoelii sporozoite infectivity varies as a function of sporozoite loads in Anopheles stephensi mosquitoes

PURPOSE: This prospective study was undertaken to determine the incremental yield of combined abdominal and pelvic CT in searching for clinically suspected postoperative abscess in oncologic patients. METHOD: One hundred seventeen oncologic patients underwent CT to exclude a clinically suspected abscess within 30 days of abdominal or pelvic surgery during an 8 month period. Scans were evaluated for the presence of ascites, loculated fluid collections, or other possible sources of fever. The clinical course and any intervention in the abdomen or pelvis within 30 days after CT were recorded. RESULTS: After abdominal surgery, 44 of 69 [64%; confidence interval (CI) 51-75%] patients had loculated fluid collections in the abdomen; no patient (0%; CI 0-5%) had a loculated fluid collection present only in the pelvis. After pelvic surgery, 22 of 48 (46%; CI 31-61%) patients had loculated fluid collections in the pelvis; no patient (0%; CI 0-7%) had a loculated collection present only in the abdomen. Loculated collections were present in both the abdomen and the pelvis in 4 of 69 (6%; CI 1.6-14%) patients after abdominal surgery and 3 of 48 (6%; CI 1.3-17%) after pelvic surgery. CONCLUSION: Isolated pelvic abscesses after abdominal surgery and isolated abdominal abscesses after pelvic surgery appear to be very uncommon in oncologic patients. CT initially need be directed only to the region of surgery in this particular patient population.     

In vitro efficacy of levofloxacin alone or in combination tested against multi-resistant Pseudomonas aeruginosa strains

PURPOSE: To describe the causes and outcomes of pediatric injuries using the emergency departments (ED) as a surveillance site. METHOD: Prospective, 14-day surveys of all injuries were conducted in the EDs of the two national trauma referral hospitals of Trinidad and Tobago. Data on patient demographics, type, cause, and outcome of injuries were collected. The chi 2 test for significance was used for categorical variables. RESULTS: Pediatric patients (< 20 years) accounted for 41.5% (714/1722) of injury visits. Of these, 62.6% were male and 17.4% were < four years old, 26.2% four to nine years, 31.1% 10 to 14 years, and 25.4% were 15 to 19 years old. Three patients (0.4%) died, 68.6% were discharged, and 31.0% admitted. Intentional injuries accounted for 13.9% of injuries. Of the intentional injuries, the assailant was significantly more likely to be known than not (P < 0.01). The most common causes of all injuries were: falls, 44.4%; blunt objects, 12.3%; sharp objects, 11.8%; motor vehicle (including pedestrians), 7.4%; poison, 3.6%; and burns, 1.7%. Injuries occurring in the home accounted for 46.2%; in school, 25.5%; sports/recreation, 11.1%; and at work, 4.5%. The most common injuries were: lacerations, 30.8%, contusions/abrasions, 26.7%, fractures, 18.8%; and sprains/dislocations, 9.4%. CONCLUSION: Pediatric injuries are a significant cause of morbidity and mortality in this country, accounting for almost one third of injured patients. Because of the low frequency of pediatric injury deaths, ED surveillance may be a more effective means of identifying high risk groups and activities for injuries. Data from EDs may be useful in other developing countries to develop injury prevention programs.