Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Objectives Antibody persistence in children following three doses of primary vaccination with diphtheria, tetanus, whole-cell-pertussis (DTwP), hepatitis B, and Haemophilus influenzae type b (Hib) vaccines (SIIL Pentavac vaccine vs. Easyfive ® of Panacea Biotec), and response to the booster dose of DTwP–Hib (Quadrovax ® ) vaccine. Methods Children who completed their primary immunization were assessed for antibodies at 15–18 months of age, and then given a booster dose of DTwP–Hib vaccine. Reactogenicity and safety of the booster dose was evaluated. Results Both pentavalent vaccines demonstrated a good immune response at 15–18 months. Following the booster dose, all vaccinated subjects achieved protective titers against diphtheria, tetanus and Hib, whereas the response to pertussis antigen was ∼78%. Fever and irritability was noted in 24%, local pain in 51%, and swelling in 36% of the children following booster dose. Conclusions Primary immunization with either pentavalent vaccine induced an excellent immunity lasting till the second year of life. A booster dose with DTwP–Hib (Quadrovax ® ) vaccine effectuated a good anamnestic response to all vaccine components, being specially strong for Hib in children previously vaccinated with SIIL liquid pentavalent vaccine (Pentavac ® ). Also, the safety profile of SIIL quadrivalent vaccine (Quadrovax ® ) administered as booster dose was acceptable. Highlights ► Pentavac ® vaccine demonstrated an excellent and long-lasting immune response. ► Quadrovax ® vaccine induces good anamnestic response to all vaccine components. ► Quadrovax vaccine was well tolerated by all vaccinees. ► No serious adverse event was reported in either group. ► Pentavac is inexpensive and is a good alternative to other costlier similar vaccines.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 The persistence of antibody obtained post-vaccination of preadolescents with three doses of Engerix-B and the effect of a booster administered 5, 10 or 15 years later were monitored in 663 vaccinees. Five, 10 and 15 years post-vaccination 〉94% of subjects had detectable antibodies and 88.2%, 86.4% and 76.7% had a titre ≥10 IU/L; GMTs were 269 IU/L, 169 IU/L and 51 IU/L, respectively; 99.1–100% vaccinees reached a titre ≥10 IU/l post-booster. GMTs were 118012 IU/L, 32477 IU/L, and 13946 IU/L when the booster was administered 5, 10 or 15 years post-vaccination, respectively. We conclude that vaccination induces immunity in the great majority of vaccinees for at least 15 years. The response to a booster dose suggests persistence of immune memory in almost all vaccinees. Although a booster dose increases substantially anti-HBs titres, the clinical relevance of such an increase remains unknown. These results do not support the need of a booster for at least 15 years when vaccinating preadolescents with Engerix-B. Highlights ► Persistence of antibody and the effect of a booster dose were monitored. ► Anti-HBs persist for at least 15 years post-primary vaccination. ► Excellent immune memory was observed in virtually all vaccines. ► Challenge doses induced long-lasting high anti-HBs titres. ► The results indicate no need in booster doses for at least 15 years post-vaccination.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Flavivirus is a genus of the family Flaviviridae . It includes West Nile virus (WNV), dengue virus (DENV), yellow fever virus (YFV), Japanese encephalitis virus (JEV), tick-borne encephalitis virus (TBEV), and several other viruses which lead to extensive morbidity and mortality in humans. To establish infection and replication in the hosts, flaviviruses have evolved a variety of strategies to modulate the host's immune responses. In this review, the strategies employed by flaviviruses to evade the innate and adaptive immunity of host are summarized based on current studies, with a major focus on the inhibition of interferon, complement, natural killer (NK) cell, B cell, and T cell responses. This review aims to provide an overview of the current understanding for the mechanisms used by flaviviruses to escape the host's immune response, which will facilitate the future studies on flavivirus pathogenesis and the development of anti-flavivirus therapeutics. Highlights ► Flaviviruses have evolved a variety of strategies to modulate the immune responses of host. ► Mechanisms by which flaviviruses evade the innate and adaptive immunity of the host are summarized based on current studies. ► Flaviviruses limit type I IFN signaling by blocking the host gene expression, thus attenuating innate immunity. ► Flaviviruses also inhibit the antiviral immune response of complement system and NK cells. ► High genetic variability of viral antigens allows viral escape from both humoral and cellular immunity against flaviviruses.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Oral mucosal vaccines have great promise for generating protective immunity against intestinal infections for the benefit of large numbers of people especially young children. There however appears to be a caveat since these vaccines have to overcome the inbuilt resistance of mucosal surfaces and secretions to inhibit antigen stimulation and responses. Unfortunately, these vaccines are not equally immunogenic nor protective in different populations. When compared to industrialized countries, children living in developing countries appear to have lower responses, but the reasons for these lowered responses are not clearly defined. The most likely explanations relate to undernutrition, micronutrient deficiencies, microbial overload on mucosal surfaces, alteration of microbiome and microbolom and irreversible changes on the mucosa as well as maternal antibodies in serum or breast milk may alter the mucosal pathology and lower immune responses to interventions using oral vaccines. The detrimental effect of adverse environment and malnutrition may bring about irreversible changes in the mucosa of children especially in the first 1000 days of life from conception to after birth and up to two years of age. This review aims to summarize the information available on lowered immune responses to mucosal vaccines and on interventions that may help address the constraints of these vaccines when they are used for children living under the greatest stress and under harmful adverse circumstances. Highlights ► Children in developing countries need different dosage/regimes of oral vaccines. ► Ty21a vaccine induced serum and mucosal B and T-cell responses were observed. ► Administration of rotavirus and OPV may lower the response to rotavirus vaccine. ► Zinc has positive effect to immune response to Dukoral and pneumococcal vaccine.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Although the importance of DNA vaccines, especially as a priming immunization has been well established in numerous HIV vaccine studies, the immunogenictiy of DNA vaccines is generally moderate. Novel adjuvant is in urgent need for improving the immunogenicity of DNA vaccine. Polysaccharide and nucleic acid fraction extracted by hot phenol method from Mycobacterium bovis bacillus Calmette-Guérin, known as BCG-PSN, is a widely used immunomodulatory product in China clinical practice. In this study, we evaluated whether the BCG-PSN could serve as a novel adjuvant of DNA vaccine to trigger better cellular and humoral immune responses against the HIV-1 Env antigen in Balb/C mouse model. The BCG-PSN was mixed with 10 μg or 100 μg of pDRVI1.0gp145 (HIV-1 CN54 gp145 gene) DNA vaccine and intramuscularly immunized two or three times. We found that BCG-PSN could significantly improve the immunogenicity of DNA vaccine when co-administered with DNA vaccine. Further, at the same vaccination schedule, BCG-PSN co-immunization with 10 μg DNA vaccine could elicit cellular and humoral immune responses which were comparable to that induced by 100 μg DNA vaccine alone. Moreover, our results demonstrate that BCG-PSN can activate TLR signaling pathways and induce Th1-type cytokines secretion. These findings suggest that BCG-PSN can serve as a novel and effective adjuvant for DNA vaccination. Highlights ► We found that BCG-PSN could significantly improve the immunogenicity of DNA vaccine when co-administered with DNA vaccine. ► DNA vaccine co-administrated with BCG-PSN could decrease 10-fold dose of vaccine requirement. ► Our results demonstrate that BCG-PSN can activate TLR signaling pathways and induce Th1-type cytokines secretion. ► Our results may provide valuable information for designing an effective HIV-1 DNA vaccine immunization strategy.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Leptospirosis is a zoonotic disease affecting animals and humans worldwide. Leptospiral infection in cattle can cause reproductive failure and reduced weight gain, and importantly, infection represents a significant disease risk for farmers. Current bacterin vaccines offer protection that is short-lived and restricted at best to related serovars. The development of protective vaccines that stimulate immunity across multiple leptospiral serovars would therefore be advantageous. This study used a reverse vaccinology approach to evaluate a set of Leptospira borgpetersenii proteins in the hamster infection model. The L. borgpetersenii serovar Hardjo strain L550 genome sequence was analysed and genes encoding 262 predicted outer membrane or secreted proteins were selected. From this list, 238 proteins or protein fragments were successfully expressed and purified; 28 proteins (12%) were soluble, while the remaining 210 proteins (88%) were insoluble and purified under denaturing conditions. Proteins were mixed into 48 pools of up to five each and tested for protection against infection as assessed by renal colonisation in the hamster model of infection. None of the pools of antigens protected the hamsters against infection, despite a detectable antibody response being mounted against the majority of proteins (71%). This study is the first large scale evaluation of individual leptospiral proteins for ability to induce a protective immune response in the hamster infection model. It thus constitutes an important reference of protein immunogenicity and non-protective antigens that should be consulted before embarking on any future subunit vaccine experiments.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 Cutaneous leishmaniasis (CL) and its associated complications, including mucocutaneous leishmaniasis (MCL) and diffuse CL (DCL) have emerged as important neglected tropical diseases in Latin America, especially in areas associated with human migration, conflict, and recent deforestation. Because of the limitations of current chemotherapeutic approaches to CL, MCL, and DCL, several prototype vaccines are in different states of product and clinical development. We constructed and utilized a Markov decision analytic computer model to evaluate the potential economic value of a preventative CL vaccine in seven countries in Latin America: Bolivia, Brazil, Colombia, Ecuador, Mexico, Peru, and Venezuela. The results indicated that even a vaccine with a relatively short duration of protection and modest efficacy could be recommended for use in targeted locations, as it could prevent a substantial number of cases at low-cost and potentially even result in cost savings. If the population in the seven countries were vaccinated using a vaccine that provides at least 10 years of protection, an estimated 41,000–144,784 CL cases could be averted, each at a cost less than the cost of current recommended treatments. Further, even a vaccine providing as little as five years duration of protection with as little as 50% efficacy remains cost-effective compared with chemotherapy; additional scenarios resembling epidemic settings such as the one that occurred in Chaparral, Colombia in 2004 demonstrate important economic benefits. Highlights ► We constructed and utilized a computer simulation model to evaluate the economic value of a CL vaccine. ► Modest protection duration and efficacy are required for CL vaccination to cost less than treatment. ► A preventative CL vaccine could save costs at moderate levels of infection risk.

Description: 7 January 2013 Publication year: 2013 Source: Vaccine, Volume 31, Issue 3 The predominant genotype of porcine circovirus (PCV) in the pig population today is PCV2b yet PCV2a-based commercial vaccines are considered effective in protecting against porcine circovirus associated disease. The objective of this study was to compare the ability of PCV2a- and PCV2b-based vaccines to control PCV2b viremia in a challenge model that mimics the U.S. field situation. Sixty-three pigs were randomly assigned to one of eight groups. Sixteen pigs were vaccinated with an experimental live-attenuated chimeric PCV1-2a vaccine based on genotype 2a and another 16 pigs with a chimeric PCV1-2b vaccine based on genotype 2b. Challenge was done 28 days post vaccination (dpv) using PCV2b (or a combination of PCV2a and PCV2b), porcine reproductive and respiratory syndrome virus (PRRSV), and porcine parvovirus (PPV) to mimic what commonly occurs in the field. The experiment was terminated 21 days post challenge (dpc) or 49 dpv. Pigs vaccinated with the chimeric PCV1-2b vaccine had significantly higher levels of PCV1-2b viremia and shedding of the PCV1-2b vaccine virus in feces and nasal secretions but also a more robust humoral immune response as evidenced by significantly higher ELISA S/P ratios compared to the PCV1-2a vaccination. Regardless of challenge, the PCV1-2b vaccination significantly reduced the prevalence and amount of PCV2 viremia compared to the PCV1-2a vaccination. Interestingly, in the non-vaccinated pigs concurrent PCV2a infection resulted in clinical disease and increased macroscopic lung lesions compared to pigs challenged with PCV2b alone, further supporting the idea that concurrent PCV2a/PCV2b infection is necessary for optimal PCV2 replication. Highlights ► Commercial PCV2 vaccines are based on PCV2a; most field infections are due to PCV2b. ► PCV2 vaccines based on genotypes 2a and 2b were compared. ► PCV2b vaccination was more effective in the experimental pig model. ► PCV2a and PCV2b coinfection resulted in clinical manifest disease.