Poly-γ-glutamic acid nanoparticles and aluminum adjuvant used as an adjuvant with a single dose of Japanese encephalitis virus-like particles provide effective protection from Japanese encephalitis virus.

To maintain immunity against Japanese encephalitis virus (JEV), a formalin-inactivated Japanese encephalitis (JE) vaccine should be administered several times. The repeated vaccination is not helpful in the case of a sudden outbreak of JEV or when urgent travel to a high-JEV-risk region is required; however, there are few single-injection JE vaccine options. In the present study, we investigated the efficacy of a single dose of a new effective JE virus-like particle preparation containing the JE envelope protein (JE-VLP). Although single administration with JE-VLP protected less than 50% of mice against lethal JEV infection, adding poly(γ-glutamic acid) nanoparticles (γ-PGA-NPs) or aluminum adjuvant (alum) to JE-VLP significantly protected more than 90% of the mice. A single injection of JE-VLP with either γ-PGA-NPs or alum induced a significantly greater anti-JEV neutralizing antibody titer than JE-VLP alone. The enhanced titers were maintained for more than 6 months, resulting in long-lasting protection of 90% of the immunized mice. Although the vaccine design needs further modification to reach 100% protection, a single dose of JE-VLP with γ-PGA-NPs may be a useful step in developing a next-generation vaccine to stop a JE outbreak or to immunize travelers or military personnel.

Evidences of protection against blood-stage infection of Plasmodium falciparum by the novel protein vaccine SE36.

An effective malaria vaccine is a public health priority. Proteins expressed during the blood-stage of the parasite life cycle have been proposed as good vaccine candidates. No such blood-stage vaccine, however, is available against Plasmodium falciparum, the deadliest Plasmodium species. We show here that P. falciparum serine repeat antigen 5 (SERA5) is a potential vaccine immunogen. We have constructed a new recombinant molecule of SERA5, namely SE36, based on previously reported SE47' molecule by removing the serine repeats. Epidemiological study in the holo-endemic population of Solomon Islands shows highly significant correlation of sero-conversion and malaria protective immunity against this antigen. Animal experiments using non-human primates, and a human phase 1a clinical trial assessed SE36 vaccine immunogenicity. Vaccination of squirrel monkeys with SE36 protein and aluminum hydroxyl gel (SE36/AHG) conferred protection against high parasitemia and boosted serum anti-SE36 IgG after P. falciparum parasite challenge. SE36/AHG was highly immunogenic in chimpanzees, where serum anti-SE36 IgG titers last more than one year. Phase 1a clinical trial (current controlled trials, ISRCTN78679862) demonstrated the safety and immunogenicity of SE36/AHG with 30 healthy adults and 10 placebo controls. Three subcutaneous administrations of 50 and 100microg dose of SE36/AHG were well-tolerated, with no severe adverse events; and resulted in 100% sero-conversion in both dose arms. The current research results for SE36/AHG provide initial clinical validation for future trials and suggest clues/strategies for further vaccine development.

Rapid and efficient introduction of a foreign gene into bacterial artificial chromosome-cloned varicella vaccine by Tn7-mediated site-specific transposition.

Using a rapid and reliable system based on Tn7-mediated site-specific transposition, we have successfully constructed a recombinant Oka varicella vaccine (vOka) expressing the mumps virus (MuV) fusion protein (F). The backbone of the vector was our previously reported vOka-BAC (bacterial artificial chromosome) genome. We inserted the transposon Tn7 attachment sequence, LacZalpha-mini-attTn7, into the region between ORF12 and ORF13 to generate a vOka-BAC-Tn genome. The MuV-F expressing cassette was transposed into the vOka-BAC genome at the mini-attTn7 transposition site. MuV-F protein was expressed in recombinant virus, rvOka-F infected cells. In addition, the MuV-F protein was cleaved in the rvOka-F infected cells as in MuV-infected cells. The growth of rvOka-F was similar to that of the original recombinant vOka without the F gene. Thus, we show that Tn7-mediated transposition is an efficient method for introducing a foreign gene expression cassette into the vOka-BAC genome as a live virus vector.

Antibody to varicella-zoster virus immediate-early protein 62 augments allodynia in zoster via brain-derived neurotrophic factor.

Varicella-zoster virus (VZV) expresses immediate-early protein 62 (IE62), and zoster is associated with neuropathic pain. Brain-derived neurotrophic factor (BDNF) is involved in the neuronal mechanism underlying pain hypersensitivity. Zoster is associated with prodrome and the robust production of booster antibody to VZV. We hypothesized that the intrathecal production of antibody to IE62 cross-reacting with BDNF and the nerve injury by skin lesions may augment allodynia in zoster by enhancing BDNF activity. One of three monoclonal antibodies against the 268-556 peptide of IE62 recognized BDNF. Immunological cross-reactivity between IE62 and BDNF and the effects of anti-IE62 monoclonal antibody (anti-IE62 MAb) cross-reactivity with BDNF on BDNF activity in cultured neurons were examined. Anti-IE62 MAb and anti-BDNF MAbs recognized the 414-429 peptide of IE62 and the BDNF dimer. Anti-IE62 MAb significantly augmented BDNF-related transcription in neurons and the morphological development of spinal dorsal horn neurons. Sera from patients recognized IE62 and BDNF and enhanced BDNF activity in neurons. The effect of anti-IE62 antibody on mechanical allodynia was characterized by the threshold of allodynia using von Frey filaments in a spinal nerve injury (SNI) in mice. The administration of anti-IE62 MAb to or immunization with cross-reacting IE62 protein to mice significantly enhanced mechanical allodynia on the side with SNI but not on the uninjured side. Anti-IE62 antibody augmented BDNF activity in neurons and allodynia in mice with SNI. The intrathecal production of anti-IE62 antibody augmenting BDNF activity and peripheral nerve injury by zoster may participate in the pathogenesis of allodynia in zoster.

Poly(gamma-glutamic acid) nano-particles combined with mucosal influenza virus hemagglutinin vaccine protects against influenza virus infection in mice.

Adding poly(gamma-glutamic acid) nano-particles (gamma-PGA-NPs), a safe, natural material, to subcutaneous immunization with influenza virus hemagglutinin (HA) vaccine increases the protective immune responses against influenza virus in mice. Here, we examined whether intranasal administration of the HA vaccine with gamma-PGA-NPs would induce protection from influenza virus challenge in mice. Intranasal immunization with the mixture of gamma-PGA-NPs and HA vaccine from an influenza virus strain A/PR/8/34 (H1N1) or A/New Caledonia/20/99 (H1N1) enhanced protection of mice from A/PR/8/34 infection. Intranasal immunization with A/New Caledonia/20/99 HA vaccine and gamma-PGA-NPs induced cell-mediated immune responses and neutralizing antibody production for both A/New Caledonia/20/99 and A/PR/8/34. These data suggest that gamma-PGA-NPs may have potential for clinical applications as a mucosal adjuvant.

DNA sequence analysis of varicella-zoster virus gene 62 from subclinical infections in healthy children immunized with the Oka varicella vaccine.

A live attenuated varicella vaccine, the Oka vaccine strain (vOka), is routinely administered to children in Japan and other countries, including the United States. vOka consists of a mixture of genotypically distinct variants, but little is known about the growth potential of each variants in vivo. We isolated varicella-zoster virus (VZV) DNA sequences from the peripheral blood mononuclear cells (PBMCs) of asymptomatic healthy children immunized with the Oka varicella vaccine. VZV gene 62 DNA fragments were detected in 5 of 166 (3.0%) PBMC samples by nested PCR within 5 weeks of the vaccination. Sequence analysis of VZV DNA from these five PBMC samples indicated that multiple viral clones in the vaccine could infect vaccinees and replicate in vivo. We also provide evidence that a nonsynonymous substitution at position 105356 may affect viral replication in vivo.

Development of varicella vaccine.

The Oka strain of varicella-zoster virus (VZV) was first isolated from vesicles of an otherwise healthy 3-year-old boy with typical varicella. The virus was passaged 11 times in human embryonic lung fibroblasts at 34 degrees C and 12 times in guinea pig embryo fibroblasts (GPEFs) at 37 degrees C. GPEFs were the only nonprimate cells tested in which some degree of viral replication occurred. The resultant virus was temperature sensitive and showed host dependency, measured as better replication in GPEFs than that shown by the parental virus. The passaged virus was used as a candidate varicella vaccine and proved safe and effective for healthy and immunocompromised children. During the follow-up of vaccinated children with acute lymphocytic leukemia, the incidence of herpes zoster (HZ) was significantly lower among children who did not have a rash after vaccination, compared with those who had a rash caused by VZV (6 [2.3%] of 260 vs. 12 [17.1%] of 70, respectively). Because of the pathogenesis of VZV, the incidence of latency and of HZ is predicted to be lower among vaccine recipients than among individuals who have experienced varicella.

Varicella-zoster virus ORF 58 gene is dispensable for viral replication in cell culture.

BACKGROUND: Open reading frame 58 (ORF58) of varicella-zoster virus (VZV) lies at the 3'end of the Unique long (UL) region and its functional is unknown. In order to clarify whether ORF58 is essential for the growth of VZV, we constructed a deletion mutant of ORF58 (pOka-BACDelta58) from the Oka parental genome cloned into a bacterial artificial chromosome (pOka-BAC). RESULTS: The ORF58-deleted virus (rpOkaDelta58) was reconstituted from the pOka-BACDelta58 genome in MRC-5 cells, indicating that the ORF58 gene is non-essential for virus growth. Comparison of the growth rate of rpOkaDelta58 and recombinant wild-type virus by assessing plaque sizes revealed no significant differences between them both in MRC-5 cells and malignant melanoma cells. CONCLUSION: This study shows that the ORF58 gene is dispensable for viral replication and does not affect the virus' ability to form plaques in vitro.

Single dose of inactivated Japanese encephalitis vaccine with poly(gamma-glutamic acid) nanoparticles provides effective protection from Japanese encephalitis virus.

Japanese encephalitis (JE) is a serious disease caused by the JE virus (JEV), and vaccination is the only way to prevent the diseases. In Japan, the only JE vaccine currently available is an inactivated vaccine that requires multiple doses for effective protection; therefore, an effective single-dose vaccine is needed. However, no report of an effective protocol for a single dose of JE vaccine in animals has been published. Here, we evaluated the efficacy of a single-dose vaccination in mice to which the JE vaccine was given with or without adjuvant. Biodegradable poly(gamma-glutamic acid) nanoparticles (gamma-PGA-NPs) were used as a test adjuvant. Remarkably, a single dose of JE vaccine with gamma-PGA-NPs enhanced the neutralizing antibody titer, and all of the immunized mice survived a normally lethal JEV infection, while only 50% of the mice that received a single dose of JE vaccine without gamma-PGA-NPs survived. The use of aluminum as the adjuvant showed similar levels of enhanced efficacy. These results show that gamma-PGA-NPs are a novel and safe adjuvant for JE vaccine, and that a single dose of JE vaccine with gamma-PGA-NPs provides effective protection from lethal JEV in mice. A similar protocol, in which a single dose of JE vaccine is mixed with gamma-PGA-NPs, may be useful for the immunization of humans.

Generation of a recombinant Oka varicella vaccine expressing mumps virus hemagglutinin-neuraminidase protein as a polyvalent live vaccine.

We constructed a recombinant varicella-zoster virus (VZV) Oka vaccine strain (vOka) that contained the mumps virus (MuV) hemagglutinin-neuraminidase (HN) gene, inserted into the site of the ORF 13 gene by using the bacterial artificial chromosome (BAC) system in Escherichia coli. Insertion of the HN gene into the VZV genome was confirmed by PCR and Southern blot. The infectious virus reconstituted from the vOka-HN genome (rvOka-HN) had a growth curve similar to the original recombinant vOka without the HN gene. The mumps virus HN protein expressed in rvOka-HN infected cells was expressed diffusely in the cytoplasm, and modification of the protein was similar to that seen in MuV-infected cells. Electron microscopic examination of infected cells revealed that HN was expressed on the plasma membrane of the cells but not in the viral envelope, suggesting that the tropism of rvOka-HN would be unchanged from that of the original vOka strain. Immunization of guinea pigs with rvOka-HN-induced VZV- and HN-specific antibodies. Interestingly, the induced antibodies had a strong neutralizing activity against virus-cell infections of both MuV and VZV. Therefore, the novel varicella vaccine expressing MuV HN protein is suitable as a polyvalent live attenuated vaccine against VZV and MuV infections.

Influenza hemagglutinin vaccine with poly(gamma-glutamic acid) nanoparticles enhances the protection against influenza virus infection through both humoral and cell-mediated immunity.

Subcutaneous immunization with an influenza hemagglutinin (HA) vaccine can induce the production of virus-neutralizing antibodies, but not a cell-mediated immune response. Here we tested whether amphiphilic poly(gamma-glutamic acid)-graft-l-phenylalanine copolymers (gamma-PGA-NPs), which are derived from a bacterial capsular exopolymer produced by certain Bacillus natto strains, were an effective adjuvant for systemic influenza HA vaccination. Subcutaneous immunization with a mixture of HA vaccine and gamma-PGA-NPs induced higher mononuclear cell proliferation and the production of gamma-interferon (IFN-gamma), interleukin (IL)-4, and IL-6 upon HA restimulation, and enhanced not only anti-HA neutralizing antibody production but also the influenza virus-specific cell-mediated immune response, including CTL activity, compared with immunization with HA alone or a mixture of HA and aluminum adjuvant. HA vaccine with gamma-PGA-NPs protected mice against challenges with lethal doses of homologous influenza virus. The results indicate that adding gamma-PGA-NPs to the HA vaccine promotes effective protection and identifies gamma-PGA-NPs as a new, effective, and potent candidate adjuvant for a subcutaneous influenza virus vaccine.

Cloning of full length genome of varicella-zoster virus vaccine strain into a bacterial artificial chromosome and reconstitution of infectious virus.

The complete genome of the varicella-zoster virus (VZV) Oka vaccine strain (vOka) has been cloned into a bacterial artificial chromosome (BAC), and several BAC clones with the vOka genome have been obtained. Infectious viruses were reconstituted in MRC-5 cells transfected with the vOka-BAC DNA clones. The clones were distributed into two groups based on differences in amino acids found in ORF 62/71 region among the vOka-BAC clones. The recombinant vOka (rvOka) grew slower than recombinant Oka parental virus (rpOka), pOka and vOka. This is the first report that the vOka genome was cloned into BAC vector. The rvOka-BAC system would be useful as a vector for construction of recombinant live vaccines.

Estimation of the neuraminidase content of influenza viruses and split-product vaccines by immunochromatography.

The neuraminidase (NA) of the influenza virus, as well as the hemagglutinin, is the most important protective components in the vaccine. However, the NA content of the vaccine remains to be standardized because of the labile nature of this glycoprotein during various chemical treatments and storage. In the present study, the NA content of the split-product (SP) vaccine (virus treated with ether then formalin) was estimated together with that of the virus by an immunochoromatography technique using monoclonal antibodies (mAbs) to viral NA for A/Panama/2007/99 (A/Pa) (H3N2), B/Shangdong/7/97 (B/S) or A/New Caledonia/20/99 (A/NC) (H1N1) viral strains. In the new method, the NA catalytic activity of each fraction from steps of NA purification was measured as an index of NA content. The NA level of A/Pa, B/S or A/NC viral particles was estimated at 6.9+/-0.9, 7.6+/-0.8 or 8.5+/-1.7% of total viral protein (not significant difference between viral strains). The NA level of the corresponding A/Pa, B/S or A/NC vaccines was estimated at 9.6+/-1.5, 12.7+/-0.4 or 12.2+/-1.2% of the total vaccine protein (a significant difference between each strain of virus and its vaccine). These results suggest that the NA content in the N1, N2 or B type NA virus ranges from 5 to 11% of the total viral protein, and that the NA level in each split-product vaccine is 1.4- to 1.6-fold higher than that in the corresponding viral particles. They also suggest that the NA content can be estimated by the immunochoromatography technique using anti-viral NA mAbs.

Cloning of the varicella-zoster virus genome as an infectious bacterial artificial chromosome in Escherichia coli.

The complete genome of the varicella-zoster virus (VZV) Oka strain has been cloned as a bacterial artificial chromosome (BAC). Following electroporation into Escherichia coli (E. coli) strain DH10B, the VZV BAC was stably propagated over multiple generations of its host. Human embryonic lung (HEL) cells transfected with VZV BAC DNA recovered from DH10B showed cytopathic effect (CPE), and virus spread to neighbouring cells was observed. BAC vector sequences are flanked by loxP sites and, coinfection of the reconstituted virus, with a recombinant adenovirus expressing Cre recombinase removed the bacterial sequences. The resulting recombinant rV02 grew as well as the parental virus in HEL cells. The recombinant VZV will promote VZV research and increase use of the viral genome as an investigative tool.

Effectiveness of live varicella vaccine.

The disease burden of chickenpox to children has been described, and a lower force of neutralising antibody to varicella-zoster virus (VZV) than against measles, either after natural infection or after vaccination, has been reported. In the case of VZV, strong cell-mediated immunity may work efficiently to prevent the spread of the virus. The lower force of humoral antibody to VZV might be related to the occurrence of "breakthrough" varicella cases in a small portion of the vaccine recipients. Safety and high effectiveness of the varicella vaccine--approximately 85% effective for all diseases and 95-100% effective for moderate-to-severe diseases--have been reported. Vaccine-induced immunity persists for 10-20 years. However, concerns have been raised that universal immunisation in children may shift the susceptibility from children to adults, whose symptoms are usually moderate-to-severe. In addition, other concerns have been expressed that, due to lack of exposure to varicella in children, the elderly may develop zoster infections more frequently than before. A clear answer is difficult to give at present, although, for several reasons, such situations may be unlikely to occur.

Pathogenetic tropism of varicella-zoster virus to primary human hepatocytes and attenuating tropism of Oka varicella vaccine strain to neonatal dermal fibroblasts.

The pathogenesis of varicella-zoster virus (VZV) was characterized by the cell tropism of the original Oka and attenuated Oka varicella vaccine strains. Among the tissue cells examined, VZV replicated best in hepatocytes and second best in lung fibroblasts. The high affinity to hepatocytes and lung fibroblasts might correlate with varicella hepatitis and pneumonia and with autopsy observations of varicella. Cell tropism may be important in understanding the pathogenesis of VZV.

Enhancement of immunity against VZV by giving live varicella vaccine to the elderly assessed by VZV skin test and IAHA, gpELISA antibody assay.

The enhancement of immunity against varicella-zoster vaccine (VZV) by subcutaneous injection of a live varicella vaccine was assessed by the VZV skin test for cell-mediated immunity (CMI), and immunoadherence hemagglutination assay (IAHA) and gpELISA antibody assays in the elderly people of 50-79 years of age. A total of 127 subjects were examined: 79 aged 50-59, 25 aged 60-69, and 25 aged 70-79. All were seropositive by the gpELISA assay (one was seronegative in the IAHA antibody assay). In contrast, a notable decline was observed in the VZV skin test with increasing age. Negative reaction was observed in 16/79 (20.2%) of the subjects in their 50s, 12/25 (48.0%) in their 60s and 14/25 (56.0%) in the 70s. After the vaccination, the results of the VZV skin test changed from negative to positive in 15/16 (91.8%) of subjects in their 50s, 11/12 (91.7%) in their 60s and 12/14 (85.7%) in their 70s. The mean antibody titer in the IAHA and the gpELISA increased approximately two-fold after the vaccination in each group. Immunity to VZV in 35 elderly subjects who were vaccinated previously was followed up for 4 years. All were positive by the VZV skin test after the previous vaccination. After 4 years, 31 (88.6%) were positive by the skin test, 4 were negative and became positive after revaccination. Although this study was uncontrolled open study, the results suggest that administering live varicella vaccine to the elderly is effective for enhancing immunity, particularly CMI to VZV.

Comparison of the complete DNA sequences of the Oka varicella vaccine and its parental virus.

The DNA sequences of the Oka varicella vaccine virus (V-Oka) and its parental virus (P-Oka) were completed. Comparison of the sequences revealed 42 base substitutions, which led to 20 amino acid conversions and length differences in tandem repeat regions (R1, R3, and R4) and in an origin of DNA replication. Amino acid substitutions existed in open reading frames (ORFs) 6, 9A, 10, 21, 31, 39, 50, 52, 55, 59, 62, and 64. Of these, 15 base substitutions, leading to eight amino acid substitutions, were in the gene 62 region alone. Further DNA sequence analysis showed that these substitutions were specific for V-Oka and were not present in nine clinical isolates. The immediate-early gene 62 product (IE62) of P-Oka had stronger transactivational activity than the mutant IE62 contained in V-Oka in 293 and CV-1 cells. An infectious center assay of a plaque-purified clone (S7-01) from the V-Oka with 8 amino acid substitutions in ORF 62 showed smaller plaque formation and less-efficient virus-spreading activity than did P-Oka in human embryonic lung cells. Another clone (S-13) with only five substitutions in ORF 62 spread slightly faster than S7-01 but not as effectively as P-Oka. Moreover, transient luciferase assay in 293 cells showed that transactivational activities of IE62s of S7-01 and S7-13 were lower than that of P-Oka. Based on these results, it appears that amino acid substitutions in ORF 62 are responsible for virus growth and spreading from infected to uninfected cells. Furthermore, the Oka vaccine virus was completely distinguishable from P-Oka and 54 clinical isolates by seven restriction-enzyme fragment length polymorphisms that detected differences in the DNA sequence.

The molecular epidemiology of varicella-zoster virus: evidence for geographic segregation.

Of 75 varicella-zoster virus (VZV) isolates obtained from patients in Africa, Asia, and the Far East, 74 (98.6%) were found to be positive for a BglI restriction site in gene 54. By contrast, <22% of strains from patients in the United Kingdom and in North and South America were positive for the BglI restriction site. Viruses positive for BglI were significantly more common in zoster occurring in patients of nonwhite origin (P<.05). Irrespective of the country in which the sample was obtained, 98% of strains positive for BglI clustered within a single phylogenetic group, which we termed "group A"; the exception was 1 strain that appeared to be recombinant genotype C/A. We used the BglI site to examine both the spread of type A viruses in the United Kingdom and the patterns of VZV infections within persons from different ethnic groups who grew up in the United Kingdom or abroad.