Simultaneous formulation of influenza vaccine and chitosan nanoparticles within CpG oligodesoxi nucleotides leads to dose-sparing and protects against lethal challenge in the mouse model

Lack of efficient delivery systems for transporting antigenic molecules to the cytosol of antigen-presenting cells presents a major obstacle for antigen uptake by immune cells. To this end, influenza whole inactivated virus vaccines were formulated with chitosan nanoparticles and CpG oligonucleotide as a biodegradable delivery system and a Th1-specific adjuvant, respectively. Intradermal injections of a single high dose and low dose of formulated candidate vaccines were carried out. Thirty days after injection, cell proliferation assay (MTT), IFN-gamma and IL-4 ELISpot assays were conducted. Sera samples were collected 21 days after immunization to measure IgG1 and IgG2a levels. In addition, the mice challenged with mouse-adopted virus were monitored for weight loss. The results show a significant stimulation of both humoral and cellular immunities; also, weight gain and a decrease in mortality in the mice receiving both dosages of inactivated influenza virus vaccines with CpG and Chitosan coating were observed. Based on the results, it can be concluded that formulation of inactivated influenza virus with CpG and its delivery by chitosan as low-dose can return the same results as with high-dose balanced between cellular and humeral immune responses. This formulation could potentially lead to a significant saving in vaccine production.

Preparation, characterization and immunological evaluation of alginate nanoparticles loaded with whole inactivated influenza virus: Dry powder formulation for nasal immunization in rabbits

It has become important to explore more efficient and feasible influenza vaccines, since epidemics of influenza virus cause hundreds of thousands of deaths all around the world. Improving immunogenicity of parentral influenza vaccines has given rise to mucosal delivery routes. In this study, alginate nanoparticles (NPs) were efficiently synthetized by ionic gelation method and influenza virus and CpG ODN or Quillaja Saponin (QS) adjuvants were actively incorporated into alginate NPs. The prepared particles were evaluated for both humoral and cellular immune responses in rabbits' nostrils. The vaccination started with a prime dose and followed by three boosters (two intranasal (IN) on days 45 and 60 and the last dose, intramuscular (IM) on day 75). HAI titer had increased in all the samples; although, only in the group received WV + CPG suspension reached to the protective HAI titer. All the immunized rabbits elicited significantly high sIgA levels on day 75, compared to the negative and the IM groups. At the end of the study, IN administration of CpG ODN adjuvant with virus antigen induced higher IgG level than the groups vaccinated with alginate NPs with or without CpG ODN (P < 0.001). As for the cellular immunity, CpG ODN was capable of inducing significant levels of IL-4 and TNF-α, either through inoculation along with the virus suspension or as incorporated in alginate NPs. According to the obtained data, CpG ODN adjuvant showed higher immunogenic potential as part of a vaccine delivery system than QS. Moreover, applying alginate polymer as a nasal delivery system carrier was not deemed immunogenic against influenza whole virus.

The role of LPD-nanoparticles containing recombinant major surface glycoprotein of Leishmania (rgp63) in protection against leishmaniasis in murine model

CONTEXT

Leishmaniasis is a major public health problem. Despite numerous attempts, yet there is no effective vaccine against human leishmaniasis, mainly due to a lack of an effective vaccine delivery system as well as adjuvant.

OBJECTIVE(S)

The aim of this study was to evaluate the ability of recombinant glycoprotein 63 (rgp63) as a model of Leishmania antigen, entrapped in liposome-polycation-DNA (LPD) complexes nanoparticles in inducing cell mediated immune (CMI) response and protecting against L. major in BALB/c mice.

MATERIALS AND METHODS

To this end, the abundant leishmania promastigote cell surface glycoprotein, gp63, was entrapped in nano-sized LPD (CpG) particles, (LPD (CpG)-rgp63), and BALB/c mice were immunized three times with either (LPD (CpG)-rgp63) or rgp63-CpG DNA or LPD (CpG) or free rgp63 and dextrose 5%. Various parameters including footpad thickness, splenic load of L. major parasites, rgp63-binding IgGs and also cytokine levels of rgp63-reactive T lymphocytes were then compared among different vaccinated animals.

RESULTS

The lowest number of parasites in spleen, the higher levels of IgG2a after challenge infection, the minimal footpad swelling and high level of IFN-γ secretion, all indicated that adjuvants and antigen-delivery systems are essential in modifying immune responses; as mice received LPD (CpG)-rgp63 induced immune response stronger than the other groups.

CONCLUSIONS

This study demonstrates that LPD nanoparticle is a promising and adaptable delivery system which could be modified towards specific vaccine targets to induce a more potent immune response in combination with rgp63.

Introduction of cationic virosome derived from vesicular stomatitis virus as a novel gene delivery system for sf9 cells

Insect-derived cell lines are used extensively to produce recombinant proteins because they are capable of performing a range of post-translational modifications. Due to their significance in biotechnological applications, various methods have been developed to transfect them. In this study, we introduce a virosome constructed from vesicular stomatitis virus (VSV) as a new delivery system for sf9 cells. We labeled these VSV virosomes by fluorescent probe Rhodamine B chloride (R18). By fluorescence microscope observation and conducting a fusion assay, we confirmed the uptake of VSV virosomes via endocytosis by sf9 cells and their fusion with the endosomal membrane. Moreover, we incubated cationic VSV virosomes with a GFP-expressing bacmid and transfected sf9 cells, after 24 h some cells expressed GFP indicating the ability of VSV virosomes to deliver heterologous DNA to these cells. This is the first report of a virosome-based delivery system introduced for an insect cell line.

Suppressive Effects of Chronic Stress on Influenza Virus Protection after Vaccination with Plasmid DNA-Encoded Nucleoprotein

BACKGROUND

Influenza is a highly infectious and acute respiratory disease caused by an infection of the host respiratory tract mucosa by the influenza virus. The use of DNA vaccines that express conserved genes such as nucleoprotein (NP) represents a new method of vaccination against influenza. In this study, the effect of chronic stress on the efficiency of this type of vaccine has been evaluated in a mouse model.

METHODS

The NP DNA vaccine was administered intradermally 3 times on days 0, 3 and 6 to stressed and nonstressed male BALB/c mice. Two weeks after the last immunization, half of these mice were challenged with A/Puerto Rico/8/34 (PR8) influenza virus and were weighed for 12 days, and their mortality rate was assessed during this period. The cellular immune response of the other half of the mice was evaluated by cytotoxicity assay.

RESULTS

The results indicate a significant reduction in the cytotoxic T-lymphocyte response of stressed mice in comparison with unstressed mice. Also, the percentage of weight loss and mortality after the challenge in stressed mice was significantly increased compared to the other group.

CONCLUSION

These results indicate that the NP DNA vaccine is not able to induce any effective cytotoxic T-lymphocyte response against influenza virus in stressed mice and cannot induce protective immunity against influenza infection in this group of mice.

In Vitro Evaluation of Influenza M2 and Leishmania major HSP70 (221-604) Chimer Protein

Background:

Permanent antigenic variation of influenza viruses causes a major concern to develop an effective human influenza vaccine. Conserved antigens are new vaccine candidates because it is not necessary to match the prepared vaccine with circulating strains. Ion channel M2 protein is conserved among all influenza A viruses, allowing the virus to enter host cells.

Objectives:

To prepare an effective vaccine against influenza A viruses, a chimerical DNA plasmid encoding Influenza virus M2 protein and Leishmania major HSP70 was constructed.

Materials and Methods:

Influenza A/New Caledonia/20/99 (H1N1) was inoculated into MDCK cell line and total RNA was extracted. The full length M2 gene was amplified by RT-PCR using designed specific primers, cloned into pGEM-T Easy cloning vector and completely sequenced. The M2 gene was then subcloned into the pcDNA upstream of HSP70 gene. Recombinant plasmids were transfected into COS-7 cells to evaluate protein expression.

Results:

The recombinant plasmids were confirmed by PCR, restriction enzyme analysis and sequencing. Three dimensional structure of chimer protein was assessed using specific software. Transient protein expression in eukaryotic cells was confirmed by specific mRNA detection, indirect Immunofluorescence test and western blotting.

Conclusions:

M2-HSP70 chimer protein was successfully expressed in eukaryotic cells. Computational studies of chimer peptide sequence revealed that fusing HSP to the C-terminal of M2 protein does not mask the predominant epitope of M2. HSP70 is a molecular chaperon and immunostimulatory component. Genetically fusing antigens to HSPs leads to the enrichment of DNA vaccine potency. The immunogenicity of this construct with different formulation would be evaluated in further investigations.

An H1-H3 chimeric influenza virosome confers complete protection against lethal challenge with PR8 (H1N1) and X47 (H3N2) viruses in mice

Annual health threats and economic damages caused by influenza virus are still a main concern of the World Health Organization and other health departments all over the world. An influenza virosome is a highly efficient immunomodulating carrier mimicking the natural antigen presentation pathway and has shown an excellent tolerability profile due to its biocompatibility and purity. The major purpose of this study was to construct a new chimeric virosome influenza vaccine containing hemagglutinin (HA) and neuraminidase (NA) proteins derived from the A/PR/8/1934 (H1N1) (PR8) and A/X/47 (H3N2) (X47) viruses, and to evaluate its efficacy as a vaccine candidate in mice. A single intramuscular vaccination with the chimeric virosomes provided complete protection against lethal challenge with the PR8 and X47 viruses. The chimeric virosomes induced high IgG antibody responses as well as hemagglutination inhibition (HAI) titers. HAI titers following the chimeric virosome vaccination were at the same level as the whole inactivated influenza vaccine. Mice immunized with the chimeric virosomes displayed considerably less weight loss and exhibited significantly reduced viral load in their lungs compared with the controls. The chimeric virosomes can be used as an innovative vaccine formulation to confer protection against a broad range of influenza viruses.

Rabbit nasal immunization against influenza by dry-powder form of chitosan nanospheres encapsulated with influenza whole virus and adjuvants

Influenza virus is one of the main causes of respiratory diseases in human. Although different vaccines have been produced during past decades, there is still a huge demand for a safe influenza vaccine with the ability to induce mucosal immune responses and sufficient protection, especially in elderly patients. In this study, chitosan nanospheres were employed as the drug delivery system. Influenza virus, CpG oligodeoxynucleotide (CpG ODN) and Quillaja saponins (QS) were incorporated in this nanospheric system. Three doses of dry powder nanosphere vaccine were nasally administered to rabbits on days 0, 45 and 60, followed by a final booster injection on day 75. Both humoral and cellular immune responses were investigated. Hemagglutination inhibition (HI) antibody titer was elevated in all groups compared to the control group at the end of vaccination in rabbits receiving nanospheres loaded with virus and CpG, CH(WV+CpG) (P<0.001). Rabbit serum IgG raised significantly in all the vaccinated groups, with the highest responses in CH(WV+CpG) group. CH(WV+CpG) and CH(WV) induced significant sIgA titers (P<0.001). CpG adjuvant also showed a prominent role in the stimulation and secretion of of IL-2 and IFN-γ cytokines (3 and 3.5 fold increase, respectively). Finally, as CH(WV+CpG) depicted to be effective in induction of humoral and cellular immune responses after nasal administration, this nanoparticulate adjuvant could be identified as an efficient adjuvant/delivery system for mucosal immunization against influenza virus.

Reconstruction of H3N2 influenza virus based virosome in-vitro

BACKGROUND AND OBJECTIVES

Virosomes are Virus Like Particles (VLP) assembled in-vitro. Influenza virosomes maintain the cell binding and membrane fusion activity of the wild type virus but are devoid of viral genetic material or internal proteins. Influenza virosomes mimic the natural antigen presentation route of the influenza virus.

METHODS

Virosomes were prepared by membrane solubilization and reconstitution. Briefly, the Madine-Darby Canine kidney (MDCK) cell line was cultivated on microcarrier beads inoculated with influenza virus strain A/X-47 (H3N2). The culture medium was harvested and clarified. Subsequently, virus was concentrated and purified by ultrafiltration and ultracentrifugation. The purified viral membrane was dissolved by adding 375 µl of 200 mM 1, 2-dicaproyl-sn-glycero-3-phosphocholine (DCPC) in HEPES-buffered saline (HBS). Nucleocapsid was removed by ultracentrifugation. The supernatant consisting of phospholipids and glycoproteins of the influenza virus was reconstituted by removal of DCPC using overnight dialysis against Hank's Buffered Saline (HBS) solution at 4°C. After dialysis, crude virosome preparation was layered over a discontinuous sucrose gradient in order to separate non-incorporated material from the reconstituted virus membranes.

RESULTS

The virosome harvested from the boundary of the two sucrose layers successfully was identified by the Hemagglutination assay and western blotting.

CONCLUSION

Use of a dialyzable short-chain phospholipid (DCPC) is an efficient procedure for solubilization and reconstitution of influenza virus virosomes and has not caused structural changes in a major envelope glycoprotein (hemagglutinin protein) on the surface of virosome.

Determining influenza virus shedding at different time points in madin-darby canine kidney cell line

OBJECTIVE

Monitoring of influenza virus shedding and optimization of multiplicities of infection (MOI) is important in the investigation of a virus one step growth cycle and for obtaining a high yield of virus in vaccine development and conventional basic diagnostic methods. However, eluted infectious viruses may still be present immediately after virus inoculation and when cells are washed following virus cultivation which may lead to a false positive virus infectivity assay.

MATERIALS AND METHODS

In this experimental study, we investigated influenza virus progeny production in Madin-Darby canine kidney (MDCK) cells with five different MOI at determined time points. The results were analyzed by end point titration tests and immunofluorescence assay.

RESULTS

Higher titers of eluted virus were observed following a high MOI inoculation of virus in cell culture. Most probably, this was the result of sialic acid residues from viral hemagglutin in proteins that were cleaved by neuraminidase glycoproteins on the surface of the influenza virus, which promoted viral spread from the host cell to the culture supernatant or during endocytosis, where viruses recycle to the cell surface by recycling endosomes which culminated in virus shedding without replication.

CONCLUSION

We demonstrated that the pattern of influenza virus progeny production was dose-dependent and not uniform. This production was influenced by several factors, particularly MOI. Understanding the exact features of viral particle propagation has a major impact in producing high virus yields in the development of vaccines. Use of lower MOI (0.01) could result in accurate, precise quantitative assays in virus diagnosis and titration methods.

The role of liposome size on the type of immune response induced in BALB/c mice against leishmaniasis: rgp63 as a model antigen

To develop an efficient liposomal vaccine delivery system, the size of liposomes is critical to their adjuvant activities. In the present study, liposomes with different sizes (100, 400, 1000 nm) containing recombinant major surface glycoprotein of Leishmania (rgp63) were prepared, characterized, and inoculated subcutaneously into BALB/c mice to evaluate the rate of protection and the type of immune response generated against leishmaniasis. The lowest footpad lesion size and splenic parasite burden were seen in the mice immunized with large size (≥400 nm) liposomes after challenge with Leishmania major. The production of IFN-γ was only elevated in the spleen cells of mice immunized with large size (≥400 nm) liposomes. The highest IgG2a/IgG1 ratio was also seen in the sera of the mice immunized with large size (≥400 nm) liposomes before and 14 weeks after challenge. The results showed that immunization with small size (100 nm) liposomes induces a Th2 response, whereas immunization with large size (≥400 nm) liposomes induces a Th1 type of immune response. There was no significant difference in the type of induced immune response between the mice immunized with liposomes of 400 nm and those immunized with liposomes of 1000 nm or unextruded. The results of the current study demonstrated that the size of liposomes plays a significant role in the type of generated immune response.

Influenza virosome/DNA vaccine complex as a new formulation to induce intra-subtypic protection against influenza virus challenge

Influenza virosome is one of the commercially available vaccines that have been used for a number of years. Like other influenza vaccines, the efficacy of the virosomal vaccine is significantly compromised when circulating viruses do not have a good match with vaccine strains due to antigenic drift or less frequent emergence of a pandemic virus. A major advantage of virosome over other influenza vaccine platforms is its intrinsic adjuvant activity and potential carrier capability which have been exploited in this study to broaden vaccine protectivity by incorporating a conserved component of influenza virus in seasonal vaccine formulation. Influenza nucleoprotein (NP)-encoding plasmid was adsorbed onto surface of influenza virosomes as a virosome/DNA vaccine complex. Mice were immunized with a single dose of the influenza virosome attached with the NP plasmid or NP plasmid alone where both influenza virosomes and NP gene were derived from influenza A virus H1N1 New/Caledonia strain. Analysis of the cellular immune responses showed that 5μg (10-fold reduced dose) of the NP plasmid attached to the virosomes induced T cell responses equivalent to those elicited by 50μg of NP plasmid alone as assessed by IFN-γ and granzyme B ELISPOT. Furthermore, the influenza virosome/NP plasmid complex protected mice against intra-subtypic challenge with the mouse adapted H1N1 PR8 virus, while mice immunized with the virosome alone did not survive. Results of hemagglutination inhibition test showed that the observed intra-subtypic cross-protection could not be attributed to neutralizing antibodies. These findings suggest that influenza virosomes could be equipped with an NP-encoding plasmid in a dose-sparing fashion to elicit anti-influenza cytotoxic immune responses and broaden the vaccine coverage against antigenic drift.

Attenuation of influenza virus infectivity with herbal-marine compound (HESA-A): an in vitro study in MDCK cells

Background

The influenza virus is still one of the most important respiratory risks affecting humans which require effective treatments. In this case, traditional medications are of interest. HESA-A is an active natural biological compound from herbal-marine origin. Previous studies have reported that the therapeutic properties of HESA-A are able to treat psoriasis vulgaris and cancers. However, no antiviral properties have been reported.

Methods

This study was designed to investigate the potential antiviral properties of HESA-A and its effects in modulating TNF-α and IL-6 cytokine levels. HESA-A was prepared in normal saline as a stock solution (0.8 mg/ml, pH = 7.4). Percentages of cell survival when exposed to different concentrations of HESA-A at different time intervals was determined by MTT assay. To study the potential antiviral activity of HESA-A, Madin-Darby Canine Kidney (MDCK) cells were treated with the effective concentration (EC₅₀) of HESA-A (0.025 mg/ml) and 100 TCID₅₀/0.1 ml of virus sample under different types of exposure.

Results

Based on the MTT method and hemagglutination assay (HA), HESA-A is capable of improving cell viability to 31% and decreasing HA titre to almost 99% in co-penetration exposures. In addition, based on quantitative real-time PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), it was found that HESA-A causes decrements in TNF-α and IL-6 cytokine expressions, which was significant for TNF-α (p ≤ 0.05) but not for IL-6.

Conclusion

In conclusion, HESA-A was effective against influenza infection through suppressing cytokine expression.

Anti-influenza Activity of a Novel Polyoxometalate Derivative (POM-4960)

There are many effective chemotherapeutic agents used in influenza disease which some of them inhibit virus replication by interfering with FluV (influenza virus) viral binding or its penetration into cell membrane. A series of polyoxometalates compounds such as POM-523 and PM-504 have been synthesized and have showed inhibitory effects on viruses. In this study we examined anti influenza activity of a novel polyoxometalate derivative (POM-4960) synthesized in the Faculty of Chemistry of Damghan University of Basic Sciences. To evaluate the anti-influenza activity of POM, following the treatment of FluV with POM at different temperatures and incubation periods, viral titer reduction was assessed by haemaglutination assay (HA). The 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine TCID50 (tissue culture infective dose) of virus, CC50 (median cytotoxic concentration) of POM, protection percentage and antiviral activity of POM in cell culture. RT-PCR and direct Immunofluorescent assays were performed to evaluate the effect of POM on viral infection and viral RNA load, respectively. POM reduced HA titer near to zero in all cell culture specimens and showed high protection against viral infection of the cells. Reduction in viral infection was confirmed by RT-PCR and Immunofluorescent staining methods. Moreover, this POM derivative has a dual (cumulative) effect on attachment and penetration inhibition compared to other POM's with just one inhibitory effect. POM-4960 could be considered as a powerful anti-influenza agent with low toxicity and high antiviral potency.

Expression of antigenic determinants of the haemagglutinin large subunit of novel influenza virus in insect cells

The global outbreak of novel A/H1N1 spread in human population worldwide has revealed an emergency need for producing a vaccine against this virus. Current influenza vaccines encounter problems with safety issues and weak response in high-risk population. It has been established that haemagglutinin is the most important viral antigen to which antibody responses are directed, and recombinant subunit vaccines, haemagglutinin of influenza A and B viruses, have been considered in order to facilitate vaccine production. In the present study, we have focused on construction of a recombinant baculovirus encoding the large subunit of novel influenza virus A/H1N1 haemagglutinin. The full genome of haemagglutinin was cloned into pGEM-TEasy vector and sequenced. The large subunit of the haemagglutinin gene was amplified by PCR using specific primers and cloned into pFast- BacHTc donor plasmid, which was then confirmed by restriction enzyme analysis and sequencing and transformed into E. coli DH10Bac competent cells. The bacmid DNA was transfected into insect cells to produce recombinant baculovirus. Expression of recombinant haemagglutinin in insect cells was determined by SDS-PAGE and immunoblotting. It has been shown that the recombinant haemagglutinin (rHA) obtained from the baculovirus insect cell expression system has suitable immunogenicity in human and can be considered as a candidate flu vac- cine. Here we produced large amounts of the HA1 protein of novel influenza A/H1N1 (Iranian isolate) in insect cells. The immunogenicity and efficacy of the recombinant HA1 will be evaluated as a vaccine candidate and compared to the recombinant HA1 produced in a prokaryotic system.

Phylogenetic Comparison of Influenza Virus Isolates from Three Medical Centers in Tehran with the Vaccine Strains during 2008-2009

BACKGROUND

Influenza virus is a major infectious pathogen of the respiratory system causing a high degree of morbidity and mortality annually. The worldwide vaccines are decided and produced annually by World Health Organization and licensed companies based on the samples collected from all over the world. The aim of this study was to determine phylogenecity and heterogenecity of the circulating influenza isolates during 2008-2009 outbreaks in Tehran, compare them with the vaccine strains that were recommended by WHO for the same period.

METHODS

Nasopharyngeal swabs (n=142) were collected from patients with influenza and influenza-like illness. Typing and subtyping of the isolates were performed using multiplex RT-PCR and phylogenetic analysis was carried out for hemagglutinin genes of the isolates.

RESULTS

Fifty out of 142 samples were positive for influenza A virus, and no influenza B virus was detected. Phylogenetic analyses revealed that the A/H1N1 isolates were related closely to A/Brisbane/59/2007, and the A/H3N2 isolates were close to A/Brisbane/10/2007 vaccine strains.

CONCLUSION

The findings of the present study demonstrate that the A/H1N1 was the predominant subtype of human influenza virus among the patients studied in Tehran during 2008-2009 winter seasons. In addition, some amino acid variation was found in Tehran/2008/H1N1 isolates from the 2008-2009 vaccine strain, but the H3N2 isolates showed higher genetic resemblance to the vaccine strain.

Molecular analysis of human influenza virus in Tehran, Iran

BACKGROUND

To date there are no reports of molecular and phylogenetic analyses of human influenza virus in Tehran, Iran.

OBJECTIVES

We isolated and characterized circulating influenza viruses in a sample of patients in Tehran.

METHODS

Nasal and pharyngeal swabs were collected from 57 individuals who were suspected of having influenza between October 2005 and January 2007. These samples were cultured and subsequently genotyped by RT-PCR and sequencing analyses.

RESULTS

Twelve of 57 samples (21%) were positive for human influenza virus. Out of the 12 positive samples, 7 were A/H3N2 (58%), 3 were A/H1N1 (25%) and 2 were B subtypes (17%). The phylogenetic analysis of the hemagglutinin gene showed that the H1N1 isolates were close to the A/New Caledonia/20/99 and the H3N2 isolates were close to the A/Panama/2007/99 and A/Moscow/10/99 vaccine strains.

CONCLUSION

In a sample of clinical patients in Tehran, Iran, the predominant subtype of human influenza virus was determined to be A/H3N2, followed by A/H1N1 and B. In addition, phylogenetic analysis on H1 showed some genetic drifts from vaccine strains, but the phylogeny of H3 demonstrated that these isolates were from the previous vaccine strains.

The role of liposome charge on immune response generated in BALB/c mice immunized with recombinant major surface glycoprotein of Leishmania (rgp63)

Liposomes as a lipid-based system have been shown to be an effective adjuvant formulation. In this study, the role of liposome charge in induction of a Th1 type of immune response and protection against leishmaniasis in BALB/c mice was studied. Liposomes containing rgp63 were prepared by Dehydration-Rehydration Vesicle (DRV) method. Neutral liposomes consisted of dipalmitoylphosphatidylcholine and cholesterol. Positively and negatively charged liposomes were prepared by adding dimethyldioctadecylammonium bromide (DDAB) or dicetyl phosphate (DCP) to the neutral liposome formulation, respectively. Female BALB/c mice were immunized subcutaneously with negatively, positively charged or neutral liposomes encapsulated with rgp63, rgp63 in soluble form or PBS, three times in 3week intervals. The extent of protection and type of immune response generated were studied in different groups of mice. The group of mice immunized with rgp63 encapsulated in neutral liposomes showed a significantly (P<0.01) smaller footpad swelling upon challenge with Leishmania major compared with positively or negatively charged liposomes. The mice immunized with neutral liposomes also showed a significantly (P<0.01) the lowest splenic parasite burden, the highest IgG2a/IgG1 ratio and IFN-gamma production and the lowest IL-4 level compared to the other groups. The results indicated that a Th1 type of immune response was induced in mice immunized with neutral liposomes more efficiently than positively charged liposomes and conversely negatively charged liposomes induced a Th2 type of immune response.

The role of CpG ODN in enhancement of immune response and protection in BALB/c mice immunized with recombinant major surface glycoprotein of Leishmania (rgp63) encapsulated in cationic liposome

CpG oligodeoxynucleotides (CpG ODN) are known to be a potent immunoadjuvant for a wide range of antigens. The aim of this study was to evaluate the role of CpG ODN co-encapsulated with rgp63 antigen in cationic liposomes (Lip-rgp63-CpG ODN) in immune response enhancement and protection in BALB/c mice against leishmaniasis. Lip-rgp63-CpG ODN prepared by using dehydration-rehydration vesicle (DRV) method significantly inhibited (P<0.001) Leishmania major infection in mice measured by footpad swelling compared to Lip-rgp63, rgp63 alone, rgp63 plus CpG ODN, PBS or control liposomes. The mice immunized with Lip-rgp63-CpG ODN also showed the lowest spleen parasite burden, highest IgG2a/IgG1 ratio and IFN-gamma production and the lowest IL-4 production compared to the other groups. The results indicate that co-encapsulation of CpG ODN in liposomes improves the immunogenicity of Leishmania antigen.

Molecular and phylogenetic analysis of human influenza virus among Iranian patients in Shiraz, Iran

Influenza is a viral respiratory pathogen responsible for frequent seasonal epidemics. There are currently three major human influenza viruses in global circulation namely A/H1N1, A/H3N2, and B. The objective of this study was to determine the human influenza virus genotypes in Shiraz, the capital of the Fars province of Iran. Three hundred patients suspected with human influenza virus infection were enrolled in this survey (2004-2005). The throat samples were cultured and titrated by hemagglutination (HA) assay. Typing and subtyping were performed by an in-house developed multiplex RT-PCR. Moreover, the phylogenetic analysis was carried out for HA gene. A total of 24 samples were found to be positive for human influenza virus infection, 17 H1N1 and 7 H3N2. These results were in agreement with the HI assay. The phylogenetic analysis results revealed that the Iranian H1N1 isolated were close to the A/New Caledonia/20/99 vaccine strain genetically and the Iranian H3N2 isolates were also related closely to the Fujian/411/021 and California/7/2004 vaccine strains. However, a slight genetic drift was found in these isolates. In conclusion, it was demonstrated that both influenza A subtypes A/H1N1 and A/H3N2 were dominant among Iranian patients in Shiraz during the 2004/5 winter season.

Immune response and protection assay of recombinant major surface glycoprotein of Leishmania (rgp63) reconstituted with liposomes in BALB/c mice

In this study the ability of recombinant gp63 entrapped in liposomes to induce immune response and protection against L. major infection in susceptible BALB/c mice was studied. Liposomes containing rgp63 (Lip-rgp63) were prepared from egg lecithin and cholesterol using detergent solubilization method. Immunization of BALB/c mice with rgp63 alone conferred a partial protection while entrapment of rgp63 in liposomes significantly increased the rate of protection (P<0.05). The parasite burden of spleen in mice challenged with L. major was significantly (p<0.001) lower in group of mice immunized with rgp63 alone or Lip-rgp63, however, the least parasite burden was seen in Lip-rgp63 group. Both rgp63 alone and Lip-rgp63 elicited significant delayed-type hypersensitivity (DTH) response compared to controls (p<0.01), however, the DTH response of PBS-rgp63 was less than the Lip-rgp63. Titration of anti-Leishmania IgG isotypes (IgG2a/IgG1) showed a preferential Th1 type of immune response only in mice immunized with Lip-rgp63. The results indicate that liposomes might be used as a suitable immunoadjuvant for development of Leishmania vaccine.