A review of influenza vaccine immunogenicity and efficacy in HIV-infected adults

BACKGROUND

HIV-seropositive adults are at an increased risk for influenza infection. They also develop more severe influenza disease and are hyporesponsive to current influenza vaccinations.

METHODS

The authors examined findings from a systematic review of influenza vaccination in HIV-seropositive adults, and evaluated other relevant studies. A narrative overview of findings formulated to summarize the implications of currently available literature is presented. The primary goal of the present review is to assess the limitations of current evidence and to provide a framework for additional research.

RESULTS

There is a paucity of knowledge regarding the relative value of prophylactic influenza vaccination in HIV-positive adults compared with immunocompetent populations. There are shortcomings related to study methodology and temporal changes in the characteristics of patient baseline immune status, which limit the utility of this information to shape public health policy.

CONCLUSIONS

There is a pressing need to pursue methodologically rigorous studies that will increase knowledge related to improving the effectiveness of preventive influenza measures in this patient population.

Sequential administration of GM-CSF and IL-2 surface-modified MB49 cells vaccines against the metastatic bladder cancer

OBJECTIVES

Many strategies are pursued to enhance tumor vaccine immune response, including the utilization of cytokines. We have developed a novel protein-anchor technology to immobilize cytokines on tumor cell surface. Here we reported the preparation of tumor cell vaccines by immobilizing GM-CSF or IL-2 on MB49 bladder cancer cells and evaluated their antitumor efficacy (administrated alone or sequentially) in a metastatic mouse model.

MATERIALS AND METHODS

SA-mGM-CSF or SA-hIL-2 surface-modified MB49 cells were prepared as vaccine. Mice were treated with MB49 cell vaccines (administrated alone or sequentially). Survival time, tumor growth, flow cytometry, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and cytotoxic T lymphocytes (CTL) assay were used to evaluate the antitumor efficiency of the vaccines in the pulmonary metastatic model of bladder cancer.

RESULTS

GM-CSF vaccine induced more mature dendritic cells in the mice spleen. Combination with subsequent IL-2 vaccine significantly increased CD4(+), CD8(+), and IFN-γ(+)CD8(+) T but not CD4(+)Foxp3(+) T cell population and induced the highest production of IFN-γ, IL-12, but not IL-10. Furthermore, the splenocytes from the sequentially combined vaccines group showed the most potent cytotoxicity on MB49 cells. Finally, the sequentially combined vaccines evidently extended the survival time of mice (the median survival time of PBS, ethanol-fixed, anchored GM-CSF, anchored IL-2, and anchored GM-CSF + anchored IL-2 groups were 34, 37, 45, 47, and 59 days, respectively) and effectively protected the mice against a second MB49 cells but not RM-1 cells challenge.

CONCLUSIONS

This study demonstrated that sequential administration of GM-CSF and IL-2 surface-modified MB49 cells vaccines could effectively induce specific antitumor immune response.

Polio Eradication in India: Myth or Reality

BACKGROUND

Poliomyelitis has been eradicated from large parts of the world. In South East Asian Region, India and Pakistan remain the only countries where active transmission of the disease persists. A decade-long initiative to eradicate the disease is in progress in India. Initial results were encouraging, with the number of fresh polio decreasing till 2001. The year 2002, however, witnessed a setback, with significant rise in cases of poliomyelitis.

METHODS AND RESULTS

The eradication measures have been reviewed. The corrective measures appear to be succeeding. Various facets of eradication and their impact are evaluated.

CONCLUSION

Poliomyelitis is controlled but the ultimate target of eradication may still be elusive, keeping in mind operational lacunae and vaccine virus characteristics.

Management and prevention of herpes zoster: A Canadian perspective

Varicella-zoster virus reactivation leads to herpes zoster - the main complication of which is postherpetic neuralgia (PHN). Rapid antiviral therapy initiated within 72 h of rash onset has been shown to accelerate rash healing, reduce the duration of acute pain and, to some extent, attenuate the development and duration of PHN. Other adjunctive therapies such as analgesics, antidepressants and some anticonvulsants are frequently required in the management of severe PHN. A live, attenuated zoster vaccine has been recently shown to significantly decrease herpes zoster incidence, PHN and the overall burden of illness when administered to adults older than 60 years of age. This new prophylactic modality has been reported to be cost-effective in the Canadian context, especially in the 60- to 75-year-old age group.

Immunological perspectives of leishmaniasis

Leishmania parasites have been widely used in experimental models to understand generation, maintenance and failure of immune responses underlying resistance and susceptibility to infection. The clinical outcomes of Leishmania infection depend on the infecting species and the immune status of the host. Noticeably most people exposed Leishmania never develop overt disease. Understanding the immunological events that result in failure or successful control of the parasites is fundamental to both design and evaluation of vaccines and therapies against the leishmaniases. Recent studies visualizing immune response to Leishmania major in the skin have given new insights into the different immune cells acting as hosts the parasite during different stage of infection. Control of Leishmania infection and disease progression has been associated with generation of T-helper (Th) 1 and Th2 responses respectively. Though still valid in several aspects, the Th1/Th2 paradigm is an oversimplification in need of revision. Th2 polarization has never explained severity of human leishmanial disease and a number of other T-cell subsets, including regulatory T- and Th17- cells, have important roles in susceptibility and resistance of both experimental and human leishmanial disease. This review gives an updated overview of immunological response considered to be of importance in protection, susceptibility, disease progression and cure of leishmaniasis, with a special emphasis on human diseases.

Towards universal childhood immunization against chickenpox?

Live attenuated varicella vaccine is available in Canada. The National Advisory Committee on Immunization recommended immunization of healthy susceptible individuals after one year of age. This was endorsed by a National Varicella Consensus Conference, provided that 90% coverage could be ensured. So far only Prince Edward Island has begun universal childhood immunization. Barriers to achieving high childhood vaccine coverage include: the perception that chickenpox is mild in children but severe in both adults and immunocompromised; concern that vaccine field effectiveness will be much lower than observed in pre-licensure efficacy trials; fear that waning immunity may increase adult cases and the associated disease burden; and uncertainty regarding long term morbidity due to vaccine strain reactivation. In fact, chickenpox is usually an uncomplicated illness in otherwise healthy individuals of all ages. Further, with varicella zoster immunoglobulin (VZIG) prophylaxis and acyclovir treatment soon after rash onset, the course in immunocompromised individuals is also usually benign. However, on a population basis, otherwise healthy children with no identifiable risk factors account for 80% to 90% of all chickenpox-associated hospital admissions and 40% to 60% of case fatalities. A more accurate assessment of the relative merits of varicella immunization should contrast the current natural history of disease (90% to 95% infected symptomatically by age 15 years, 15% lifetime risk of a moderate to severe reactivation episode) with the demonstrated vaccine effectiveness of 70% to 86% against any chickenpox, 95% to 100% against moderate to severe illness and significant reduction of frequency and severity of reactivation illness.

Leishmaniasis Vaccine: Where are We Today?

Leishmaniasis is a disease that ranges in severity from skin lesions to serious disfigurement and fatal systemic infection. WHO has classified the disease as emerging and uncontrolled and estimates that the infection results in two million new cases a year. There are 12 million people currently infected worldwide, and leishmaniasis threatens 350 million people in 88 countries. Current treatment is based on chemotherapy, which relies on a handful of drugs with serious limitations such as high cost, toxicity, difficult route of administration and lack of efficacy in endemic areas. Vaccination remains the best hope for control of all forms of the disease, and the development of a safe, effective and affordable antileishmanial vaccine is a critical global public-health priority. Extensive evidence from studies in animal models indicates that solid protection can be achieved by immunization with defined subunit vaccines or live-attenuated strains of Leishmania. However, to date, no such vaccine is available despite substantial efforts by many laboratories. The major impediment in vaccine design is the translation of data from animal models to human disease, and the transition from the laboratory to the field. Furthermore, a thorough understanding of protective immune responses and generation and maintenance of the immunological memory, the most important and least-studied aspect of antiparasitic vaccine development, during Leishmania infection is needed. This review focuses on recent findings in antileishmania vaccine field and highlights current difficulties facing vaccine development and implementation.

A comparison of pertussis rates in the Northwest Territories: Pre- and postacellular pertussis vaccine introduction in children and adolescents

INTRODUCTION

During the past decade, a trend toward increasing cases of Bordetella pertussis in older children and adults has been witnessed in Canada. The National Advisory Committee on Immunization now recommends that the adult formulation of the acellular pertussis (adult dTap) vaccine combined with diphtheria and tetanus toxoids be substituted for diphtheria and tetanus toxoids alone for the 14- to 16-year-old booster dose. In October 2000, the government of the Northwest Territories was one of the first to adopt adult dTap into their territorial immunization program free of charge.

OBJECTIVE

To evaluate the effect of the acellular pertussis vaccine in children and adolescents on the epidemiology of pertussis in the Northwest Territories.

METHODS

Pertussis is a reportable disease in the Northwest Territories, and data on the incidence rates of pertussis are available from 1989 to 2004. The present study reviews pertussis cases during three four-year periods: the whole-cell vaccine era (1993 to 1996); the preadult dTap era (1997 to 2000); and the postadult dTap era (2001 to 2004).

RESULTS

The incidence of pertussis decreased from 18.0 cases per 10,000 population in 1993 to 0.2 cases per 10,000 population in 2004. The number of cases decreased from 186 to 129 to 19 cases in the three chronological time periods (ie, whole-cell vaccine era, preadult dTap era and postadult dTap era, respectively), with the most substantial reduction coming with the introduction of postadult dTap.

CONCLUSIONS

There appears to be a decrease in the incidence of pertussis with the targeted introduction of adult dTap in the Northwest Territories.

Burden of chickenpox on families: A study in Quebec

OBJECTIVE

To estimate the nonhospital costs of treating chickenpox and to ascertain the opinion of parents regarding the usefulness of vaccination.

DESIGN

Retrospective postal survey.

SETTING

Province of Quebec.

PARTICIPANTS

Random sample of 3333 families with children aged six months to 12 years.

OUTCOME MEASURES

For cases of chickenpox that occurred between September 1, 1997 and August 31, 1998, the use of health services, time away from school or work, patient care required, direct and indirect costs for the families and the health care system, and the opinion of parents regarding chickenpox and the vaccine were evaluated.

RESULTS

The response rate was 64.7%, and 18.8% of households reported a history of chickenpox, a total of 693 cases. A physician was consulted in 45.8% of these cases, and medication was used in 91.7%. The frequency of hospitalizations was 0.6%. Time away from work or school caused by the disease was 4.1 days on average, with 46.5% of absences being attributed to the risk of contagion. The total average cost of a case of chickenpox was $225. Direct expenses for households accounted for 11% of the total cost, public sector direct costs 7%, indirect costs related to absence from work 38% and caregiving time 45%. A majority of parents (70%) were in favour of a systematic childhood immunization program.

CONCLUSIONS

Chickenpox without complications is disruptive for families, but the direct costs for families and the public sector are relatively small.

Rotavirus infection: a perspective on epidemiology, genomic diversity and vaccine strategies

For centuries, acute diarrhea has been a major cause of death in young children worldwide, and until 1973, before rotavirus was discovered; no infectious agents could be identified in about 80% of patients admitted to hospital with severe dehydrating diarrhea. Rotaviruses have now been shown to cause 40-50% of severe acute diarrhea in young children worldwide in both developing and developed countries. More than 600,000 young children die and approximately 2.4 million hospitalize annually from rotavirus disease, especially in South-East Asia and sub-Saharan Africa. Two safe and effective vaccines are now licensed in 100 countries but used in 17 countries. Rotarix (GSK) vaccine is derived from single attenuated human rotavirus G1P[8], representative of the most common serotype identified worldwide. RotaTeq (Merck) is a pentavalent mixture of naturally attenuated bovine/human rotavirus reassortants representing G1, G2, G3, G4, and P[8] serotypes. Though these vaccines have already dramatically decreased the morbidity associated with rotavirus in countries where they are widely used, the third generation of vaccines, based on inactivated viruses or recombinant virus like particle are already in pipeline. Continuous surveillance and the genetic and antigenic analysis of the various strains of rotavirus circulating worldwide will aid significantly in assessing the effectiveness of these vaccines and monitor emergence of new strains. Introduction of rotavirus vaccines in national vaccine policy along with other childhood vaccines may result in significant reduction in mortality in children in poor socioeconomic countries.

Idiotype vaccines for lymphoma: Potential factors predicting the induction of immune responses

Over the last two decades, lymphoma idiotype vaccines have been the first human cancer vaccines to show striking evidence of biological and clinical efficacy on the one hand, as well as clinical benefit on the other. More recently, however, three large-scale, independent, randomized clinical trials on idiotypic vaccination have failed to achieve their main clinical endpoints for reasons likely to depend more on flaws in each clinical trial’s study design than on each vaccination strategy per se. Independently of these considerations, a major hurdle for the development of this substantially innocuous and yet potentially very effective type of treatment has been the fact that, even to date, no factors ascertainable before vaccination have been prospectively singled out as predictors of subsequently vaccine-induced, idiotype-specific immune as well as clinical responses. The aim of this review article is precisely to analyze what has been and what could be done in this respect in order to give a greater chance of success to future trials aimed at regulatory approval of idiotype vaccines.

Tuberculin Reactivity in School Age Children; Five-year Follow-up in Iran

OBJECTIVE

Tuberculosis (TB) is an important infectious disease worldwide. Tuberculin skin test (TST) is the standard test for diagnosis of tuberculosis infection; Bacillus Calmette-Guerin (BCG) vaccination at birth has effects on this test. The aim of this study was to determine the prevalence of positive TST cases among 7- to 11-year-old primary school children and also to follow test-positive individuals for a five-year period.

METHODS

TST was performed on 10.184 children aged 7-11 years sampled by cluster random method in Kermanshah, West Iran. Those who had a positive test result (i.e. an induration of ≥15 mm following 72 hours of injecting 0.1 ml of 5 tuberculin units of purified protein derivative from Mycobacterium tuberculosis) were followed for five years to determine the presence of active TB. Also tuberculin positive rates at cut-off points of 10 mm and ≥15 mm for boys and girls and at different ages were derived and compared using the chi-squared test.

FINDINGS

Of 10.184 studied subjects, 830 (8.15%) cases showed positive TST. This rate was 8.7% in boys and 7.8% in girls (P=0.1). A significant linear trend was found between the tuberculin positive rates and age at all cut-off points (P<0.001). No active TB was detected during 5-year follow-up.

CONCLUSION

The rate of positive TST cases in primary school children in Kermanshah, Iran was 8.15% with no new cases of active tuberculosis detection within five-year follow-up.

Hepatitis B Vaccine Coverage and the Immune Response in Children under ten years old in Sana'a, Yemen

OBJECTIVES

The study was undertaken, first, to determine the coverage rate of hepatitis B (HB) vaccine and second to evaluate the immune response to HB vaccine among children under 10 years old by measuring the level of circulating anti-HB surface antigen (anti-HBs) antibodies after immunisation with three doses.

METHODS

First, 840 children were randomly selected from 4 randomly selected sites in Sana'a city to study the coverage rate of the vaccine; of these, 504 children vaccinated against HBV prior to the study, were tested (56% males and 44% females). Sera were tested for anti-HBs antibodies by ELISA quantitative technique. Each individual's data was collected in a pre-designed questionnaire including: vaccination date, sex, and age at the time of the study.

RESULTS

The coverage rate of HBV vaccine was only 69.9%, being slightly higher among male children (72.1%) than female children (66.8%). A total of 276 (54.8%) of the 504 children responded to the vaccine with anti-HBs antibody level ≥ 10 mIU/ml, while 228 (45.2%) of the 504 children had non-protective anti-HBs antibodies levels (<10IU/ml). Children of ages 3-5 years had the highest protective rate (63.6%), and the lowest protective rate was in the 9-10 years age group.

CONCLUSION

This study revealed a low coverage rate of HBV vaccine and a low protective rate against HBV infection. A considerable proportion of vaccinated children should be considered for either revaccination or booster doses. There is also the need to complete HBV vaccine coverage among the child population in San'a, Yemen.

Ovine rotaviruses

Rotavirus has been recognized as a predominant cause of acute diarrhea in young animals and humans. Rotavirus has segmented genome composed of 11 segments of double stranded RNA. The virus has a triple layered protein shell consisting of a core, an inner capsid and an outer capsid. The inner capsid protein is responsible for group specificity and based on it rotaviruses are classified into seven groups. Ovine rotavirus strains have only been identified into two serogroups (A and B). The two outer capsid proteins (VP7 and VP4) are responsible for G and P typing of rotavirus, respectively. Although rotavirus has been frequently reported in many animal species, data regarding ovine rotavirus strains is very scanty and limited. Only a few ovine rotaviruses have been isolated and characterized so far. Recently, the G and P types circulating in ovines have been identified. The ovine rotavirus strain NT isolated from a diarrheic lamb in China is being considered as a promising vaccine candidate for human infants.

A Recombinant Adenovirus Encoding Multiple HIV-1 Epitopes Induces Stronger CD4+ T cell Responses than a DNA Vaccine in Mice

T-cell based vaccines against SIV/HIV may reduce both transmission and disease progression by inducing broad and functionally relevant T cell responses. Mounting evidence points toward a critical role for CD4⁺ T cells in the control of immunodeficiency and virus replication. We have previously shown that a DNA vaccine (HIVBr18), encoding 18 HIV CD4 epitopes capable of binding to multiple HLA class II molecules was able to elicit broad, polyfunctional, and long-lived CD4⁺ and CD8⁺ T cell responses in BALB/c and multiple HLA class II transgenic mice. By virtue of inducing broad responses against conserved CD4⁺ T cell epitopes that could be recognized across diverse common HLA class II alleles, this vaccine concept may cope with HIV-1 genetic variability and increase population coverage. Given the low immunogenicity of DNA vaccines in clinical trials, we tested the ability of a recombinant adenovirus serotype 5 encoding the 18 HIV epitopes (Ad5-HIVBr18) to increase specific cellular immune responses. We assessed the breadth and magnitude of HIV-specific proliferative and cytokine responses of CD4⁺ and CD8⁺ T cells induced by Ad5-HIVBr18 using different vaccination regimens/routes and compared to DNA immunization. Immunization with Ad5-HIVBr18 induced significantly higher specific CD4⁺ and CD8⁺ T cell proliferation, IFN-γ and TNF-α production than HIVBr18. The subcutaneous route of Ad5-HIVBr18 administration was associated with the highest responses. Ad5-HIVBr18 induced higher proliferative and cytokine responses than HIVBr18 up to 28 weeks post-immunization. Our results indicate that a vaccine based on an adenovirus vector encoding the HIVBr18 epitopes shows superior immunogenicity as compared to its DNA counterpart. These results support the possible testing of a vaccine encoding HIVBr18 in non-human primates and future clinical trials.

Streptococcus pneumoniae meningitis in Alberta pre- and postintroduction of the 7-valent pneumococcal conjugate vaccine

OBJECTIVE

To describe the epidemiology, clinical characteristics, microbiology and outcomes of patients of all ages with Streptococcus pneumoniae meningitis two years pre- and postintroduction of a S pneumoniae 7-valent conjugate vaccine program in Alberta in children <2 years of age.

METHODS

Between 2000 and 2004, all cases of invasive pneumococcal disease in Alberta were identified. From this cohort, patients with S pneumoniae meningitis were identified by chart review. Clinical data, laboratory data and in-hospital outcomes were collected.

RESULTS

Of the 1768 cases of invasive pneumococcal disease identified between 2000 and 2004, 110 (6.2%) had S pneumoniae meningitis. The overall incidence was 0.7 per 100,000 persons and remained unchanged over the study period. The rate in children <2 years of age appeared to fall over time, from 10.5 per 100,000 persons in 2000 to five per 100,000 persons in 2004, although there was insufficient evidence of a statistically significant time trend within any age group. Overall, the mean age was 30 years and 47% were male. In-hospital mortality was 20%, ranging from 6% in those ≤2 years of age to 31% for those ≥18 years of age, despite appropriate antimicrobial therapy.

CONCLUSION

The high mortality rate associated with S pneumoniae meningitis suggests that prevention by vaccination is critical. In children <2 years of age, there was a downward trend in the rate of S pneumoniae meningitis after implementation of the S pneumoniae 7-valent conjugate vaccine program, but rates were still high.

Antigen-expressing immunostimulatory liposomes as a genetically programmable synthetic vaccine

Liposomes are versatile (sub)micron-sized membrane vesicles that can be used for a variety of applications, including drug delivery and in vivo imaging but they also represent excellent models for artificial membranes or cells. Several studies have demonstrated that in vitro transcription and translation can take place inside liposomes to obtain compartmentalized production of functional proteins within the liposomes (Kita et al. in Chembiochem 9(15):2403–2410, 2008; Moritani et al.in FEBS J, 2010; Kuruma et al. in Methods Mol Biol 607:161–171, 2010; Murtas et al. in Biochem Biophys Res Commun 363(1):12–17, 2007; Sunami et al. in Anal Biochem 357(1):128–136, 2006; Ishikawa et al. in FEBS Lett 576(3):387–390, 2004; Oberholzer et al. in Biochem Biophys Res Commun 261(2):238–241, 1999). Such a minimal artificial cell-based model is ideal for synthetic biology based applications. In this study, we propose the use of liposomes as artificial microbes for vaccination. These artificial microbes can be genetically programmed to produce specific antigens at will. To show proof-of-concept for this artificial cell-based platform, a bacterial in vitro transcription and translation system together with a gene construct encoding the model antigen β-galactosidase were entrapped inside multilamellar liposomes. Vaccination studies in mice showed that such antigen-expressing immunostimulatory liposomes (AnExILs) elicited higher specific humoral immune responses against the produced antigen (β-galactosidase) than control vaccines (i.e. AnExILs without genetic input, liposomal β-galactosidase or pDNA encoding β-galactosidase). In conclusion, AnExILs present a new platform for DNA-based vaccines which combines antigen production, adjuvanticity and delivery in one system and which offer several advantages over existing vaccine formulations.

Antibody responses to 43 and 48 kDa antigens of blood-stage Plasmodium berghei in Balb/c mice

Progress towards a vaccine against malaria is advancing rapidly with several candidate antigens being tested for their safety and efficacy. In present investigation, two polypeptides (43 and 48 kDa) of Plasmodium berghei (NK-65) were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Immunogenicity and protective efficacy of both these polypeptides formulated in saponin has been compared in Balb/c mice against challenge infection with P. berghei. Antibody responses were evaluated by indirect fluorescent antibody test and enzyme-linked immunosorbent assay. Merozoite invasion inhibition assay and challenge infections revealed that 48 kDa antigen is better immunogen as compared to 43 kDa and provide better protection against rodent malaria infection.

Recommendations for the use of rotavirus vaccines in infants

Rotavirus infection occurs in the majority of healthy children before five years of age, and is the most common diarrheal illness associated with hospitalization. The majority of children present with symptoms of vomiting, diarrhea and fever. As a result, rotavirus gastroenteritis is responsible for greater morbidity than other common childhood diarrheal illnesses. The highest risk of severe disease is in children younger than two years of age. It is estimated that one in 20 children will require an emergency department visit. In addition to community-acquired infections, hospital-acquired infections are also significant. There are currently two licensed rotavirus vaccines in Canada. Both vaccines are administered orally and are highly effective against severe disease and hospitalization. Large pre- and postmarketing studies have shown no increased risk of intussusception with the current rotavirus vaccines. The present statement provides information concerning the clinical disease and rotavirus vaccines in Canada.

Reemergence of Chikungunya virus in Indian Subcontinent

Chikungunya virus (CHIKV), a reemerging arboviral disease of public health concern is characterized by a triad of fever, rash and arthralgia. It was responsible for a number of epidemics in Asia and Africa. The severity of the current epidemic can be judged by the fact that an estimated 1.38 million people in India and one-third of the La Reunion population (by April 2006) were affected by CHIKV. Aedes aegypti and Aedes albopictus are the major mosquitoes transmitting CHIKV in Asia. Various neurological complications and CHIKV associated deaths were encountered during the current outbreak (2005-2010). The aggressive nature of the recent CHIKV epidemic was attributed to the mutations in the viral genome in addition to their adaptation and spread to vectors like Aedes albopictus. Proper diet, adequate rest and symptomatic treatment using non-salicylate analgesics and Non-steroidal anti inflammatory drugs (NSAIDS) helped the patients in recovering from CHIKV infections. In the absence of an effective vaccine, rapid implementation of mosquito control measures and establishment of a system for continuous surveillance of the disease seems to be the only possible solution to prevent any such outbreak in the near future.

Understanding the Influenza A H1N1 2009 Pandemic

A new strain of Influenza A virus, with quadruple segment translocation in its RNA, caused an outbreak of human infection in April 2009 in USA and Mexico. It was classified as Influenza A H1N1 2009. The genetic material originates from three different species: human, avian and swine. By June 2009, the World Health Organization (WHO) had classified this strain as a pandemic virus, making it the first pandemic in 40 years. Influenza A H1N1 2009 is transmitted by respiratory droplets; the transmissibility of this strain is higher than other influenza strains which made infection control difficult. The majority of cases of H1N1 2009 were mild and self limiting, but some people developed complications and others died. Most laboratory tests are insensitive except the polymerase chain reaction (PCR) which is expensive and labour intensive. The Influenza A H1N1 2009 virus is sensitive to neuraminidase inhibitors (oseltamivir and zanamivir), but some isolates resistant to oseltamivir have been reported. A vaccine against the new pandemic strain was available by mid-September 2009 with very good immunogenicity and safety profile. Surveillance is very important at all stages of any pandemic to detect and monitor the trend of viral infections and to prevent the occurrence of future pandemics. The aim of this review is to understand pandemic influenza viruses, and what strategies can be used for surveillance, mitigation and control.

Population-based surveillance of Hib invasive infections in children in British Columbia Alberta and Ontario - 1995 to 1997

OBJECTIVE

To assess vaccine effectiveness through enhanced disease surveillance following the change in childhood immunization programs in 1995, when all provinces and territories chose to use polyribosyl ribitol phosphate-tetanus protein (PRP-T) Haemophilus influenzae type b (Hib) conjugate vaccine, generally in combination with diphtheria-pertussis-tetanus inactivated polio vaccine (DPT-IPV) (as PENTA vaccine) because the protective efficacy of this regimen had not been directly measured.

DESIGN

Prospective, active, laboratory-based Hib case surveillance was implemented in British Columbia and Alberta, and enhanced, stimulated laboratory surveillance in Ontario during 1995 to 1997, centred on invasive infections in children. Case details and immunization histories were uniformly collected and centrally collated.

MAIN RESULTS

Thirty-eight Hib cases were detected, but only 12 cases arose among PENTA-eligible children, an attack rate of 0.85 cases/100,000 child-years of observation. Annual case totals declined from 20 in 1995 to seven in 1997, when only one to three cases were encountered in each province and the incidence rate in children under age five years was 0.6/100,000. Only four cases occurred after primary immunization with PENTA, a failure rate of 0.28 cases/100,000 child-years of observation. Three cases among PENTA-eligible children reflected parental refusal of infant vaccinations, accounting for 25% of cases in eligible children.

CONCLUSIONS

PRP-T conjugate vaccine was highly effective when given in combination with DPT-IPV vaccine. Provincial programs that used this regimen resulted in the near elimination of invasive Hib disease in children, but unimmunized children remain at risk.

Advances in immunology of hepatitis E virus infection

Hepatitis E virus (HEV) is the cause of human hepatitis E. Hepatitis E is endemic in many developing countries, including China, and represents a major public health problem. In this article, we will review the current knowledge on humoral and cellular immune responses and mechanisms of immunologic injury in HEV infection as well as the development of HEV vaccines.

Pneumococcal peritonitis: Still with us and likely to increase in importance

BACKGROUND

Pneumococcal peritonitis is uncommon and poorly understood.

METHODS

As part of a five-year study (2000 to 2004) of invasive pneumococcal disease (IPD) in Alberta, all cases of peritonitis due to Streptococcus pneumoniae were reviewed and compared with all other cases of IPD.

RESULTS

Twenty-three of 1768 (1.3%) IPD patients were found to have peritonitis. Patients with peritonitis were more likely to have cirrhosis, hepatitis C, alcoholism and HIV/AIDS, than the remainder of the patients with IPD. The all-cause mortality did not differ between the two groups. Peritonitis was classified as primary in nine (39%) patients, secondary in 12 (52%) patients, and genitourinary in females, specifically, in two (9%) patients. Pneumococcal serotypes causing peritonitis were under-represented in current vaccines - 17% among peritonitis patients versus 53% for the remainder of IPD patients for the 7-valent pneumococcal conjugate vaccine, and 56% versus 86% for the 23-valent pneumococcal polysaccharide vaccine.

CONCLUSIONS

Peritonitis represents a small subset of patients with IPD, but one that is likely to grow in importance given the increase in the number of patients with hepatitis C and HIV, and the reduced coverage of peritonitis serotypes in currently available vaccines.

Emerging vaccine therapy approaches for prostate cancer

Prostate cancer vaccines attempt to induce clinically relevant, cancer-specific systemic immune responses in patients with prostate cancer and represent a new class of targeted, nontoxic therapies. With a growing array of vaccine technologies in preclinical or clinical development, autologous antigen-presenting cell vaccines loaded with the antigen, prostate acid phosphatase, and poxvirus vaccines targeting prostate-specific antigen have recently demonstrated a significant survival benefit in randomized trials of patients with metastatic castration-resistant prostate cancer, whereas others have failed to demonstrate any benefit. The combination of vaccines with chemotherapy, radiotherapy, and other biologic agents is also being evaluated. Efforts to optimize vaccine approaches and select ideal patient populations need to continue to build on these early successes.

Vaccines for immunological control of fertility

Vaccines have been proposed as one of the strategies for population control. Immunocontraceptive vaccines can be designed to inhibit: (1) production of gametes (sperm and egg); (2) functions of gametes, leading to blocking of fertilization; and (3) gamete outcome (pregnancy). Immunization with gonadotropin-releasing hormone coupled to different carriers has shown curtailment in the production of sperm with concomitant infertility in various species. Immunization of nonhuman primates and men with ovine follicle stimulating hormone has also resulted in reduced sperm output. Various spermatozoa-specific proteins such as FA1, PH-20, LDH-C₄, SP-10, SP-17, sp56, SPAG9, and Izumo have been proposed as candidate antigens to develop contraceptive vaccines, which have shown efficacy in inhibiting fertility in different animal models. Immunization with zona pellucida glycoproteins-based immunogens also results in curtailment of fertility in a variety of species. However, ways to overcome the observed oophoritis associated with zona proteins immunization have yet to be discovered, a necessary step before their proposal for control of human population. Nonetheless, this is a very promising approach to control wildlife animal population. Phase II clinical trials of β-human chorionic gonadotropin-based vaccine in women have established the proof of principle that it is possible to inhibit fertility without any untoward side-effects by vaccination. Further scientific inputs are required to increase the efficacy of contraceptive vaccines and establish their safety beyond doubt, before they can become applicable for control of fertility in humans.

Acute gastroenteritis in a pediatric hospital in rio de janeiro in pre- and post-rotavirus vaccination settings

A 4½-year hospital-based survey was conducted in Rio de Janeiro to determine baseline rates of gastroenteritis-related cases, hospitalizations, and deaths; to examine the prevalence of rotavirus strains causing admissions; and to assess the immediate impact of the nationwide rotavirus immunization program launched in March 2006. From August 2002 to May 2007, 14,473 (10.4%) of the 139,747 consultations had AGE as primary diagnosis, 491 (3.4%) children required hospitalization and two (0.4%) dehydrated children died. Gastroenteritis contribution to hospitalizations varied from ~2.3% in 2004 and 2006 to 6.4% in 2005, being roughly half of them rotavirus-related cases. A gradual decrease in rotavirus strain diversity was observed from 2002 to 2005 when a single G9P[8] prevailed until April 2006. Then only short profile G9P[4] and G2P[4] strains were detected. Gastroenteritis cases were distributed year-round in a trimodal pattern with major winter peaks. Local climate apparently affected the incidence of gastroenteritis: reduction in dry years (2004 and 2007) and explosive outbreaks caused by multiple agents during the heavy rainfalls and recurrent floods of the 2005-early 2006 period. Besides rotavirus, adenovirus and calicivirus were major gastroenteritis agents of these seemingly waterborne outbreaks. In conclusion, rotavirus vaccination impacted marginally, if at all, on the incidence of childhood gastroenteritis, as favorable results obtained by comparing data from the post-vaccine period to the preceding unusual 2005 year all but disappeared when comparing to previous pre-vaccination periods, and the shift towards G2P[4] rotavirus strains may be a global trend unrelated to vaccination.

Immunopathogenesis of hepatitis B persistent infection: implications for immunotherapeutic strategies

It has been shown that cellular immunity, especially by cytotoxic T lymphocytes (CTLs), NK cells and NK-T cells, plays a central role in the control of virus infection. In addition, CD4+ T cells facilitate both CTL and B-cell responses. Hyporesponsiveness of HBV-specific T cells in peripheral blood has been shown in patients with chronic HBV infection. Interferon and nucleos(t)ide analogs, such as lamivudine, adefovir, entecavir and tenofovir, are the currently available treatments. Unfortunately, the efficacy of nucleos(t)ide analogs is limited by viral reactivation by the emergence of escaped mutants in cases of prolonged treatment. Therefore, immunotherapy is one of the significant options to eradicate or control HBV replication without drugs. The aim of immunotherapies is to decrease the levels of viral replication and to eradicate infected hepatocytes. For this reason, new strategies for immunotherapies by vaccination target not only the induction or stimulation of CD4+ and CD8+ T cell responses, but also the induction of proinflammatory cytokines capable of controlling viral replication. We will review the immunopathogenesis of persistent HBV infection, especially focusing on the mechanisms of immune suppression. Then we will review the immunotherapy for HBV persistent infection.

The role of immunotherapy in prostate cancer: an overview of current approaches in development

Ongoing clinical trials provide promise for the introduction of immunotherapy into the armamentarium against prostate cancer, but the precise role for immunotherapy remains to be determined. Combinations of immunotherapies may be needed to improve the response rates and the duration of response. Investigators have begun to examine the effect of immunotherapy in combination with other standard treatment, including as an adjuvant to chemotherapy or radiotherapy and as a neoadjuvant agent before prostatectomy. Although many studies examine efficacy in men with metastatic hormone-refractory prostate cancer, there is some evidence for improved responses at earlier stages of disease: the ability of the tumor to evade the immune system may be lessened with lower tumor burden, or the immune system may already be weakened in men with later stages of disease.

Preparation and evaluation of an experimental iscom-based infectious bursal disease vaccine

The present study was conducted to develop and evaluate an experimental ISCOM-based infectious bursal disease (IBD) vaccine. The indigenous very virulent infectious bursal disease virus (vvIBDV) already attenuated and adapted to Vero cell line was used. After denaturation of viral proteins with sodium dodecyl sulphate (SDS), an IBD-ISCOM was constructed. The non-incorporated viral components were separated from ISCOM by centrifugation of dialysate. The pathogenicity and immunogenicity trials were conducted in 3-week-old broiler chicken. A commercial oil-emulsified vaccine (CEVAC IBD K) was used for comparison. There were no clinical signs of disease, gross or microscopic lesions in bursa of Fabricius in group G1 vaccinated with ISCOM-based vaccine and bursa to body weight ratio were comparable to un-vaccinated control group (G3). The virus-neutralizing antibody titers were significantly (P<0.05) higher in group G1 as compared with group G2 which was vaccinated with commercial vaccine. On challenge with vvIBDV, 100%, 75% and 0.00% protection was achieved in G1, G2 and G3, respectively. The results indicated that ISCOM-based IBD vaccine is safe and immunogenic.

Preparation of FMD type A87/IRN inactivated vaccine by gamma irradiation and the immune response on guinea pig

FMD is one of the most economically damaging diseases that affect livestock animals. In this study FMD Virus type A87/IRN was multiplied on BHK21 cells. The virus was titrated by TCID50 method, it was 10(7.5)/ml. The FMD virus samples were inactivated by gamma ray from 60Co source at -20°C. Safety test was done by IBRS2 monolayer cell culture method, also antigenicity of irradiated and un-irradiated virus samples were studied by Complement Fixation Test. The Dose/Survival curve for irradiated FMD Virus was drawn, the optimum dose range for inactivation of FMDV type A87/IRN and unaltered antigenicity was obtained 40-44 kGy. The inactivated virus samples by irradiation and ethyleneimine (EI) were formulated respectively as vaccine with Al(OH)3 gel and other substances. The vaccines were inoculated to Guinea pigs and the results of Serum Neutralization Test for the normal vaccine and radio-vaccine showed protective titer after 8 months. The potency test of the inactivated vaccines was done, PD50 Value of the vaccines were calculated 7.06 and 5.6 for inactivated vaccine by EI and gamma irradiation respectively.

Heparanase: a novel target of tumor metastasis therapy

Heparanase plays a key role in promoting tumor angiogenesis, vasiveness and metastasis. This predominant enzyme is primarily responsible for cleaving heparin sulphate, the main polysaccharide constituent of extracellular matrix and basement membrane, thus having become a novel target of tumor therapy. It can prevent tumor growth and metastasis by inhibiting its expression and reducing its activity. This paper reviews the biological characteristics of heparanase as a target of tumor therapy, the significance in tumor progression and tumor therapies, and the prospect of its relating medicine in clinical applications.

Human papillomavirus: the usefulness of risk factors in determining who should get vaccinated

Vaccination against human papillomavirus (HPV) promises to dramatically decrease the incidence of HPV-related diseases, including cervical cancer. Although this vaccine is recommended by the Advisory Committee on Immunization Practices and The American College of Obstetricians and Gynecologists for all age-eligible women, challenges related to the vaccine's high cost and the difficulty in reaching some patients for vaccination may make implementation of this recommendation difficult. As an alternative strategy, some may consider targeting HPV vaccines to specific patients based on their risk for HPV infection or HPV-related disease. This article reviews what is known about risk factors for HPV, and discusses why using risk factors as the basis for targeting HPV vaccination is unlikely to be a viable vaccination strategy.

Vaccination guidelines: a bridge between official requirements and the daily use of vaccines

Vaccination guidelines are non-compulsory recommendations which assist the veterinary practitioner to use vaccines efficiently. They complement the official information contained in the shortened form of the summary of product characteristics that is included in the package insert of the product. The aim of this article is to clarify the role of guidelines and examine how they can improve the use of vaccines in practical conditions. The development of vaccination guidelines is explained. Several issues are discussed: primary vaccination schedule; interference with maternally derived antibodies; duration of immunity; vaccination and ageing. Three guidelines dealing with the vaccination of cats against upper respiratory tract disease are compared, as an example. In conclusion, vaccination guidelines are essential tools to assist veterinarians in good vaccination practices. They fill the gap that exists between the official recommendations included in the regulations and the licensing dossiers and the daily use of the vaccines.

Synergistic anti-tumor effect of recombinant chicken fibroblast growth factor receptor-1-mediated anti-angiogenesis and low-dose gemcitabine in a mouse colon adenocarcinoma model

AIM: To evaluate whether the combination of recom-binant chicken fibroblast growth factor receptor -1 (FGFR-1) protein vaccine (cFR-1) combined with low-dose gemcitabine would improve anti-tumor efficacy in a mouse CT26 colon adenocarcinoma (CT26) model.

METHODS: The CT26 model was established in BABL/c mice. Seven days after tumor cell injection, mice were randomly divided into four groups: combination therapy, cFR-1 alone, gemcitabine alone, and normal saline groups. Tumor growth, survival rate of tumor-bearing mice, and systemic toxicity were observed. The presence of anti-tumor auto-antibodies was detected by Western blot analysis and enzyme-linked immunospot assay, microvessel density (MVD) of the tumors and tumor cell proliferation were detected by Immunohistochemistry staining, and tumor cell apoptosis was detected by TdT-mediated biotinylated-dUTP nick end label staining.

RESULTS: The combination therapy results in apparent decreases in tumor volume, microvessel density and tumor cell proliferation, and an increase in apoptosis without obvious side-effects as compared with either therapy alone or normal control groups. Also, both auto-antibodies and the antibody-producing B cells against mouse FGFR-1 were detected in mice immunized with cFR-1 vaccine alone or with combination therapy, but not in non-immunized mice. In addition, the deposition of auto-antibodies on endothelial cells from mice immunized with cFR-1 was observed by immunofluorescent stain-ing, but not on endothelial cells from control groups. Synergistic indexes of tumor volume, MVD, cell apoptosis and proliferation in the combination therapy group were 1.71 vs 1.15 vs 1.11 and 1.04, respectively, 31 d after tumor cell injection.

CONCLUSION: The combination of cFR-1-mediated anti-angiogenesis and low-dose gemcitabine synergistically enhances the anti-tumor activity without overt toxicity in mice.

Hepatitis A vaccine associated with autoimmune hepatitis

To describe a case of probable relapsing autoimmune hepatitis associated with vaccination against hepatitis A virus (HAV). A case report and review of literature were written concerning autoimmune hepatitis in association with hepatitis A and other hepatotropic viruses. Soon after the administration of formalin-inactivated hepatitis A vaccine, a man who had recently recovered from an uncharacterized but self-limiting hepatitic illness, experienced a severe deterioration (AST 1687 U/L, INR 1.4). Anti-nuclear antibodies were detectable, and liver biopsy was compatible with autoimmune hepatitis. The observation supports the role of HAV as a trigger of autoimmune hepatitis. Studies in helper T-cell activity and antibody expression against hepatic proteins in the context of hepatitis A infection are summarized, and the concept of molecular mimicry with regard to other forms of viral hepatitis and autoimmunity is briefly explored.

Th immune response induced by H pylori vaccine with chitosan as adjuvant and its relation to immune protection

AIM: To study the immunological protective effect of H pylori vaccine with chitosan as an adjuvant and its mechanism.

METHODS: Female BALB/c mice were randomly divided into seven groups and orally immunized respectively with PBS, chitosan solution, chitosan particles, H pylori antigen, H pylori antigen plus cholera toxin (CT), H pylori antigen plus chitosan solution, H pylori antigen plus chitosan particles once a week for four weeks. Four weeks after the last immunization, the mice were challenged twice by alive H pylori (1 × 10⁹ CFU/mL) and sacrificed. Part of the gastric mucosa was embedded in paraffin, cut into sections and assayed with Giemsa staining. Part of the gastric mucosa was used to quantitatively culture H pylori. ELISA was used to detect cytokine level in gastric mucosa and anti- H pylori IgG1, IgG2a levels in serum.

RESULTS: In the groups with chitosan as an adjuvant, immunological protection was achieved in 60% mice, which was significantly higher than in groups with H pylori antigen alone and without H pylori antigen (P < 0.05 or 0.001). Before challenge, the level of IFN and IL-12 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in the control group and the group without adjuvant (P < 0.05 or 0.005). After challenge, the level of IFN and IL-12 was significantly higher in the groups with adjuvant than in the groups without adjuvant and antigen (P < 0.05 or 0.001). Before challenge, the level of IL-2 in gastric mucosa was not different among different groups. After challenge the level of IL-2 was significantly higher in the groups with adjuvant than in the control group (P < 0.05 or 0.001). Before challenge, the level of IL-10 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in other groups without adjuvant (P < 0.05 or 0.01). After challenge, the level of IL-10 was not different among different groups. Before challenge, the level of IL-4 in gastric mucosa was significantly higher in the groups with chitosan as an adjuvant than in other groups without adjuvant (P < 0.05). After challenge, the level of IL-4 was significantly higher in the groups with chitosan particles as an adjuvant than in the group with CT as an adjuvant (P < 0.05), and in the group with chitosan solution as an adjuvant, the level of IL-4 was significantly higher than that in control group, non-adjuvant group and the groups with CT (P < 0.05 or 0.001). The ratio of anti- H pylori IgG2a/IgG1 in serum was significantly lower in the groups with chitosan as an adjuvant than in the groups with CT as an adjuvant or without adjuvant (P < 0.01).

CONCLUSION: H pylori vaccine with chitosan as an adjuvant can protect against H pylori infection and induce both Th1 and Th2 type immune response.

The burden of pneumococcal disease in the Canadian population before routine use of the seven-valent pneumococcal conjugate vaccine

BACKGROUND

In the United States, implementation of the seven-valent conjugate vaccine into childhood immunization schedules has had an effect on the burden of pneumococcal disease in all ages of the population. To evaluate the impact in Canada, it is essential to have an estimate of the burden of pneumococcal disease before routine use of the vaccine.

METHODS

The incidence and costs of pneumococcal disease in the Canadian population in 2001 were estimated from various sources, including published studies, provincial databases and expert opinion.

RESULTS

In 2001, there were 565,000 cases of pneumococcal disease in the Canadian population, with invasive infections representing 0.7%, pneumonia 7.5% and acute otitis media 91.8% of cases. There were a total of 3000 deaths, mainly as a result of pneumonia and largely attributable to the population aged 65 years or older. There were 54,330 life-years lost due to pneumococcal disease, and 37,430 quality-adjusted life-years lost due to acute disease, long-term sequelae and deaths. Societal costs were estimated to be $193 million (range $155 to $295 million), with 82% borne by the health system and 18% borne by families. Invasive pneumococcal infections represented 17% of the costs and noninvasive infections represented 83%, with approximately one-half of this proportion attributable to acute otitis media and myringotomy.

CONCLUSIONS

The burden of pneumococcal disease before routine use of the pneumococcal conjugate vaccine was substantial in all age groups of the Canadian population. This estimate provides a baseline for further analysis of the direct and indirect impacts of the vaccine.

Immunogenicity of recombinant hepatitis B virus vaccine in patients with and without chronic hepatitis C virus infection: A case-control study

AIM: To compare the response of standard hepatitis B virus (HBV) vaccination between patients with chronic hepatitis C virus (HCV) infection and healthy individuals.

METHODS: This is a prospective case-control study. A total of 38 patients with chronic HCV infection and 40 healthy controls were included. Vaccination was performed by injection of 20 μg recombinant HBsAg into the deltoid muscle at mo 0, 1 and 6. Anti-HBs concentration was determined 3 mo after the last dose and compared between the two groups. The response pattern was characterized as (1) high-response when the anti-HBs antibody titer was > 100 IU/L, (2) low-response when the titer was 10-100 IU/L and (3) no-response when the titer was < 10 IU/L.

RESULTS: In the patient group, there were 10/38 (26.3%) non-responders, 8/38 (21.1%) low-responders and 20/38 (52.6%) high-responders. The corresponding values in the control group were 2/40 (5.0%), 7/40 (17.5%) and 31/40 (77.5%), respectively. The response pattern was statistically different between the two groups. In multivariate analysis, smoking was a significant confounder, while HCV infection lost its significant correlation with lower antibody response.

CONCLUSION: Patients with chronic HCV infection tend to respond weakly to HBV vaccination compared to healthy individuals, though this correlation is not independent according to multivariate analysis.

Influence factors of post-immunization gastritis after Helicobacter pylori vaccine immunization in mice

AIM: To explore the influence factors of post-immunization gastritis after H. pylori vaccine immunization in mice.

METHODS: (1) C₅₇BL/6 and BALB/c mice were orally immunized with H. pylori vaccine (H. pylori whole cell sonicate antigen plus mucosa adjuvant cholera toxin). Gastric H. pylori infection and inflammation were evaluated after H. pylori challenge. (2) C₅₇BL/6 mice were orally immunized with H. pylori vaccine, and then challenged by different amounts of H. pylori. Gastric H. pylori infection and inflammation were evaluated after H. pylori challenge. (3) C₅₇BL/6 mice were immunized orally or intraperitoneally with H. pylori vaccine. Gastric H. pylori infection and inflammation were evaluated after H. pylori challenge at different time points. (4) Infected C₅₇BL/6 mice were orally immunized with H. pylori vaccine, and gastric H. pylori infection and inflammation were evaluated after immunization at different time points.

RESULTS: (1) Similar decreasing of H. pylori colonization was found in both C₅₇BL/6 and BALB/c mice. However, C₅₇BL/6 mice showed more severe post-immunization gastritis than BALB/c mice did. (2) Although H. pylori colonization was similar in all groups with different challenging amounts, larger amount of H. pylori challenge induced more severe post-immunization gastritis. (3) Similar post-immunization gastritis and decreasing of H. pylori colonization were found in mice with both oral and intraperitoneal immunization at different time points. (4) Therapeutic immunization led to significant decreasing of H. pylori colonization in infected mice; meanwhile more severe gastritis was also found in therapeutic group when compared with that in control group.

CONCLUSION: Post-immunization gastritis occurs in different immune hosts, the same hosts with different vaccination routes and hosts received therapeutic immunization. H. pylori challenge amounts and immune host are influential factors of post-immunization gastritis degree.

Coimmunization with IL-15 plasmid enhances the longevity of CD8 T cells induced by DNA encoding hepatitis B virus core antigen

AIM: To test the feasibility of delivering a plasmid encoding IL-15 as a DNA vaccine adjuvant for improving the immune responses induced by hepatitis B virus core gene DNA vaccine.

METHODS: We used RT-PCR based strategies to develop IL-15 expression constructs. We first confirmed that the gene could be expressed in Escherichia coli due to the poor expression of IL-15. Then the bioactivity of IL-15 plasmid expression product was identified by CTLL-2 proliferation assay. One hundred micrograms of DNA from each of the IL-15 eukaryotic expressed plasmid and the recombinant plasmid harboring DNA encoding the 144 amino acids of the N-terminus of HBV core gene (abbreviated pHBc144) was used to co-immunize C57 BL/6 mice. The titer of anti-HBcIgG was detected by ELISA and the antigen-specific CD8⁺ T cells (CD8⁺IFN-γ⁺ T cells) were detected by intracellular cytokine staining at different time points.

RESULTS: After co-immunization by pIL-15 and pHBc144 DNA vaccine the antigen-specific CD8⁺ cells of mice increased gradually, the first peak of immune response appeared 14 d later, then the number of antigen-specific CD8⁺ Ts cells decreased gradually and maintained at a steady level in 3 mo. After boosting, the number of antigen-specific CD8⁺ T cells reached the second peak 10 d later with a double of the 1st peak, then the number of antigen-specific CD8⁺ T cells decreased slowly. IL-15 as a gene adjuvant had no significant effect on humoral immune responses induced by hepatitis B virus core gene DNA vaccine, but increased the memory antigen-specific CD8⁺ T cells induced by hepatitis B virus core gene DNA vaccine.

CONCLUSION: DNA vaccine constructed by HBc Ag 1-144 amino acid induces effective cell immunity, and cytokine plasmid-delivered IL-15 enhances the longevity of CD8⁺ T cells.

Expression, purification and characterization of enterovirus-71 virus-like particles

AIM: Enterovirus 71 (EV71) has been implicated as the etiological agent responsible for the recent outbreaks of hand, foot and mouth disease associated with severe neurological diseases in the Asia-Pacific region.

METHODS: The assembly process was hypothesized to occur via an orchestrated proteolytic processing of the P1 precursor by the viral protease 3CD. To test this hypothesis, we constructed 3 recombinant baculoviruses: Bac-P1 expressing P1; Bac-3CD expressing 3CD; and Bac-P1-3CD co-expressing P1 and 3CD.

RESULTS: Both single infection by Bac-P1-3CD and co-infection by Bac-P1 and Bac-3CD resulted in correct cleavage of P1 to yield individual proteins VP0, VP1 and VP3, while the former approach yielded higher VLP production. In the cells, the structural proteins self-assembled into clusters of virus-like particles (VLP) resembling the authentic EV71 particle aggregates. After ultracentrifugation purification, the dispersed VLPs were indistinguishable from the authentic virus in size, appearance, composition and surface epitopes, as determined by SDS-PAGE, Western blot, transmission electron microscopy and immunogold labeling.

CONCLUSION: Our data, for the first time, suggest that in insect cells EV71 structural proteins adopt a processing and assembly pathway similar to poliovirus assembly. The preservation of particle morphology and composition suggest that the VLP may be a valuable vaccine candidate to prevent EV71 epidemics.

Current situation in the development of a preventive HIV vaccine

The uncontrolled progression of the aids epidemic has made the development of an efficacious human immunodeficiency virus (HIV) vaccine a major objective of scientific research. No effective preventive vaccine against HIV is currently available and sterilizing immunity has not yet been achieved in animal models. This review analyses the major challenges in developing an aids vaccine, in particular the mechanisms involved in viral escape from the immune response, and summarizes the results obtained with the different prototypes of therapeutic and preventive vaccines. Finally, social, economic and healthcare aspects of research into HIV vaccines and current controversies regarding the development of clinical trials are discussed.

Depletion of CD25+CD4+T cells (Tregs) enhances the HBV-specific CD8+ T cell response primed by DNA immunization

AIM: Persistent hepatitis B virus (HBV) infection is characterized by a weak CD8⁺ T cell response to HBV. Immunotherapeutic strategies that overcome tolerance and boost these suboptimal responses may facilitate viral clearance in chronically infected individuals. Therefore, we examined whether CD25⁺CD4⁺ regulatory T (Treg) cells might be involved in a inhibition of CD8⁺ T cell priming or in the modulation of the magnitude of the ‘peak’ antiviral CD8⁺ T cell response primed by DNA immunization.

METHODS: B10.D2 mice were immunized once with plasmid pCMV-S. Mice received 500 μg of anti-CD25 mAb injected intraperitoneally 3 d before DNA immunization to deplete CD25⁺ cells. Induction of HBV-specific CD8⁺ T cells in peripheral blood mononuclear cells (PBMCs) was measured by S28-39 peptide loaded DimerX staining and their function was analyzed by intracellular IFN-γ staining.

RESULTS: DNA immunization induced HBV-specific CD8⁺ T cells. At the peak T cell response (d 10), 7.1±2.0% of CD8⁺ T cells were HBV-specific after DNA immunization, whereas 12.7±3.2% of CD8⁺ T cells were HBV-specific in Treg-depleted mice, suggesting that DNA immunization induced more antigen-specific CD8⁺ T cells in the absence of CD25⁺ Treg cells (n = 6, P<0.05). Similarly, fewer HBV-specific memory T cells were detected in the presence of these cells (1.3±0.4%) in comparison to Treg-depleted mice (2.6±0.9%) on d 30 after DNA immunization (n = 6, P<0.01). Both IFN-γ production and the avidity of the HBV-specific CD8⁺ T cell response to antigen were higher in HBV-specific CD8⁺ T cells induced in the absence of Treg cells.

CONCLUSION: CD25⁺ Treg cells suppress priming and/or expansion of antigen-specific CD8⁺ T cells during DNA immunization and the peak CD8⁺ T cell response is enhanced by depleting this cell population. Furthermore, Treg cells appear to be involved in the contraction phase of the CD8⁺ T cell response and may affect the quality of memory T cell pools. The elimination of Treg cells or their inhibition may be important in immunotherapeutic strategies to control HBV infection by inducing virus-specific cytotoxic T lymphocyte responses in chronically infected subjects.

Clinical significance of CD1a and survivin expression in gastric carcinoma

AIM: To investigate the distribution of dendritic cells (DCs) and DC precursors in gastric carcinoma (GC) and to discuss the possibility of survivin as the target antigen in GC immunotherapy.

METHODS: Immunohistochemical staining was used to detect the expression of CD1a, CD68, S100 and survivin protein in 132 cases of GC tissues, including 72 cases of moderately differentiated adenocarcinomas and 60 poorly differentiated ones.

RESULTS: The expression of CD1a in moderately differentiated GCs(33%, 24/72) was significantly higher (c² = 6.56, P<0.05) than that in poorly differentiated ones (10%, 6/60). S100 expression was not markedly different between moderately (50%, 36/72) and poorly (30%, 18/60) differentiated GCs (P>0.05). The expression of CD1a was positively related to S100 protein. The distribution of CD68 molecules in moderately and poorly differentiated GCs was and 60% respectively and there was no significantly difference between them (P>0.05). The expression CD1a was also positively related to CD68 in GC.The expression of survivin protein was 91.7% (66/72) and 90%(54/60) in moderately and poorly differentiated GCs respectively, and there was no significant difference between them.

CONCLUSION: Combination of survivin and DC may play a valuable role in GC immunotherapy, and further studies on individualized DC vaccine against GC targeted on survivin antigen should be made in the future.

Combination effect of human B7-2 and dentric cells vaccines in anti-esophageal cancer in vitro

AIM: To investigate the roles of human B7-2 combined with dentric cell (DC) vaccine in inducing anti-tumor immunity against esophageal cancer in vitro.

METHODS: Human esophageal cancer cell line EC9706 was transfected with the vector of pEGFP-N3-B7-2 by lipofectamine method. The mononuclear cells (MNCs) were separated from cord blood by density gradient centrifugation (Ficall-Hypaque) and then were induced to differentiate by cell factors. On the 3^rd day, EC9706 cytolysis antigen was added into the medium, in which DCs gradually matured and expressed special tumor antigen. After the matured DCs were co-cultured with autologous T cells derived from cord blood for 3 days, the T cells were activated to become tumor specific cytotoxic T lymphocytes (CTL). The inhibition of CTL on the transfected and untransfected EC9706 cells was detected by methyl thiazolyl tetrazolium (MTT) assay.

RESULTS: The EGFP-B7-2 fusion gene was expressed mainly on the membrane of EC9706 cells, which proved the transfection was successful. Mature DCs with tumor cytolysis antigene was able to activate naive T cells to become tumor specialized CTL, and the CTL had significant inhibitory effect or killing response on EC9706 cells transfected with pEGFP-N3-B7-2(F = 21.672,P = 0.000).

CONCLUSION: The human B7-2 combined with DC vaccine can induce significant killing response on esophageal cancer cell.

Phage displaying peptides mimic schistosoma antigenic epitopes selected by rat natural antibodies and protective immunity induced by their immunization in mice

AIM: To obtain the short peptides mimic antigenic epitopes selected by rat natural antibodies to schistosomes, and to explore their immunoprotection against schistosomiasis in mice.

METHODS: Adults worm antigens (AWA) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked transferred immunoblotting methods with normal SD rat sera (NRS). The killing effects on schistosomula with fresh and heat-inactivated sera from SD rats were observed. Then the purified IgG from sera of SD rats was used to biopan a phage random peptide library and 20 randomly selected positive clones were detected by ELISA and 2 of them were sequenced. Sixty female mice were immunized thrice with positive phage clones (0, 2^nd, 4^th wk). Each mouse was challenged with 40 cercariae, and all mice were killed 42 d after challenge. The worms and the liver eggs were counted.

RESULTS: NRS could specifically react to the molecules of 75000, 47000, 34500 and 23000 of AWA. Sera from SD rats showed that the mortality rate of schistosomula was 76.2%, and when the sera were heat-inactivated in vitro, the mortality rate was decreased to 41.0% after being cultured for 48 h. The specific phages bound to IgG were enriched about 300-folds after three rounds of biopanning. Twenty clones were detected by ELISA, 19 of them bound to the specific IgG of rat sera. Immunization with these epitopes was carried out in mice. Compared with the control groups, the mixture of two mimic peptides could induce 34.9% (P = 0.000) worm reduction and 67.6% (P = 0.000) total liver egg reduction in mice. Two different mimic peptides could respectively induce 31.0% (P = 0.001), 14.5% (P = 0.074) worm reduction and 61.2% (P = 0.000), 35.7% (P = 0.000) total liver egg reduction. The specific antibody could be induced by immunization of the mimic peptides, and the antibody titer in immunized mice reached more than 1:6400 as detected by ELISA.

CONCLUSION: Specific peptides mimic antigenic molecules can be obtained by biopanning the phage random peptide library and a partially protective immunity against schistosome infection can be stimulated by these phage epitopes in mice.

Enhancement of humoral immune responses to HBsAg by heat shock protein gp96 and its N-terminal fragment in mice

AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragment of gp96 could substitute native gp96 to stimulate the immune system.

METHODS: gp96 isolated from livers of normal mice and its N-terminal fragment (amino acid 22-355) expressed in E coli were used for immunization of BALb/c mice. Eight groups of mice received one of the following regiments subcutaneously in 100 μL phosphate buffered saline (PBS) at an interval of 3 wk. Group 1: PBS only; group 2: gp96 only; group 3: N-terminal fragment only; group 4: HBsAg only; group 5: HBsAg+gp96; group 6: HBsAg+N-terminal fragment; group 7: HBsAg+incomplete Freud’s adjuvant; group 8: HBsAg+N-terminal fragment (95 °C heated for 30 min). Serum anti-HBsAg antibody levels were assayed by ELISA. CTL responses in splenocytes were analyzed by ELISPOT after the last vaccination.

RESULTS: The average titer of serum anti-HBsAg antibody in the mice immunized with HBsAg together with gp96 or its N-terminal fragment were much higher than those immunized with HBsAg alone detected by ELISA. The cellular immune response of the mice immunized with HBsAg together with gp96 or its N-terminal fragment was not different with those immunized with HBsAg alone measured by ELISPOT assay.

CONCLUSION: gp96 or its N-terminal fragment greatly improved humoral immune response induced by HBsAg, but failed to enhance the CTL response, which demonstrated the potential of using gp96 or its N-terminal fragment as a possible adjuvant to augment humoral immune response against HBV infection.