Attenuated live infectious bronchitis virus QX vaccine disseminates slowly to target organs distant from the site of inoculation.

Infectious bronchitis (IB) is a highly contagious respiratory disease of poultry, caused by the avian coronavirus infectious bronchitis virus (IBV). Currently, one of the most relevant genotypes circulating worldwide is IBV-QX (GI-19), for which vaccines have been developed by passaging virulent QX strains in embryonated chicken eggs. Here we explored the attenuated phenotype of a commercially available QX live vaccine, IB Primo QX, in specific pathogens free broilers. At hatch, birds were inoculated with QX vaccine or its virulent progenitor IBV-D388, and postmortem swabs and tissues were collected each day up to eight days post infection to assess viral replication and morphological changes. In the trachea, viral RNA replication and protein expression were comparable in both groups. Both viruses induced morphologically comparable lesions in the trachea, albeit with a short delay in the vaccinated birds. In contrast, in the kidney, QX vaccine viral RNA was nearly absent, which coincided with the lack of any morphological changes in this organ. This was in contrast to high viral RNA titers and abundant lesions in the kidney after IBV D388 infection. Furthermore, QX vaccine showed reduced ability to reach and replicate in conjunctivae and intestines including cloaca, resulting in significantly lower titers and delayed protein expression, respectively. Nephropathogenic IBVs might reach the kidney also via an ascending route from the cloaca, based on our observation that viral RNA was detected in the cloaca one day before detection in the kidney. In the kidney distal tubular segments, collecting ducts and ureter were positive for viral antigen. Taken together, the attenuated phenotype of QX vaccine seems to rely on slower dissemination and lower replication in target tissues other than the site of inoculation.

Determination of the minimum protective dose of a glycoprotein-G-deficient infectious laryngotracheitis virus vaccine delivered via eye-drop to week-old chickens.

Infectious laryngotracheitis (ILT) is an upper respiratory tract disease of chickens that is caused by infectious laryngotracheitis virus (ILTV), an alphaherpesvirus. This disease causes significant economic loses in poultry industries worldwide. Despite widespread use of commercial live attenuated vaccines, many poultry industries continue to experience outbreaks of disease caused by ILTV. Efforts to improve the control of this disease have resulted in the generation of new vaccine candidates, including ILTV mutants deficient in virulence factors. A glycoprotein G deletion mutant vaccine strain of ILTV (ΔgG ILTV), recently licenced as Vaxsafe ILT (Bioproperties Pty Ltd), has been extensively characterised in vitro and in vivo, but the minimum effective dose required to protect inoculated animals has not been determined. This study performed a vaccination and challenge experiment to determine the minimum dose of ΔgG ILTV that, when delivered by eye-drop to seven-day-old specific pathogen-free chickens, would protect the birds from a robust challenge with a virulent field strain of virus (class 9 ILTV). A dose of 10(3.8) plaque forming units was the lowest dose capable of providing a high level of protection against challenge, as measured by clinical signs of disease, tracheal pathology and virus replication after challenge. This study has shown that the ΔgG ILTV vaccine strain is capable of inducing a high level of protection against a virulent field virus at a commercially feasible dose. These results lay the foundations upon which a commercial vaccine can be developed, thereby offering the potential to provide producers with another important tool to help control ILTV.

The efficacy, biodistribution and safety of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis.

DNA vaccines, the third-generation vaccines, were extensively studied. The attenuated Salmonella choleraesuis (S. choleraesuis) was widely focused as a carrier to deliver DNA vaccines in the chromosome-plasmid balanced-lethal system. The efficacy of inhibin DNA vaccine delivered by attenuated S. choleraesuis was proved in mice and cows in our previous studies. In this study, the efficacy of inhibin DNA vaccine was confirmed in rhesus monkeys. To further study the biodistribution and safety, the mice were immunized under laboratory conditions. The results of the rhesus monkeys showed the plasma IgA and IgG titres against inhibin were elevated, and the oestradiol (E2 ) and progesterone (P4 ) levels were increased with immunizing inhibin DNA vaccine. The biodistribution and safety assessment displayed the body weight, pathological change and haematology indexes where there is no significant difference between vaccinated mice and control. And the genomics analysis showed there was no integration of the inhibin gene into the mouse genome 2 months after immunization. This study indicated the inhibin DNA vaccine delivered by attenuated S. choleraesuis was safe. And this vaccine was a potential means to improve their reproductive traits in primates and other animals.

Vaccination with 3-dose paediatric rotavirus vaccine (RotaTeq®): impact on the timeliness of uptake of the primary course of DTPa vaccine.

BACKGROUND: In countries like Australia where high coverage rates of early childhood vaccines has been achieved, ensuring timely vaccination is the next challenge--particularly where multiple doses are required for protection (e.g. DTPa vaccine). Since July 2007, for the first time, the Australian childhood vaccination schedule has included a vaccine (rotavirus vaccine) that must be administered within strict dosing windows. AIM: To determine whether the introduction of a 3-dose rotavirus vaccine (RotaTeq® into the national childhood immunisation program in Victoria, Australia, had an impact on the timeliness of the primary course of DTPa vaccine that is also scheduled at the same ages (2, 4 and 6 months). STUDY: We studied de-identified data of >17,000 children residing in four large and culturally diverse localities in the Eastern Region of Melbourne, Victoria who were born prior to or after the introduction of RotaTeq® into the National Immunisation Program schedule. Timeliness was defined as the proportion of children who received a particular dose of DTPa vaccine within the dosing window for the equivalent dose of RotaTeq®. We were particularly interested in any change in the timeliness of dose 3 of DTPa vaccine. RESULTS: Before the introduction of RotaTeq®, timely uptake of doses 1 and 2 of DTPa vaccine was high (93-97%). However, timeliness of the 3rd dose was markedly lower, dropping to 80% in one locality. In the post-RotaTeq® cohort, rates of timely uptake for doses 1 and 2 of DTPa vaccine remained high (97-99%). However, for DTPa vaccine dose 3, there was a clear trend toward improved timeliness--increasing by 5 to up to 12 percentage points compared with the pre-RotaTeq® cohort. CONCLUSION: Inclusion in the national immunisation schedule of the 3-dose vaccine RotaTeq® that has strict dosing windows encourages parents to present in a timely fashion for their child's vaccination, which in turn may drive an improvement in timeliness of other concurrently scheduled vaccines (e.g. DTPa). Introduction of government-funded RotaTeq® may improve the uptake of the crucial 3rd dose of DTPa vaccine, where traditionally the greatest delays are noted.

Microneedle array design determines the induction of protective memory CD8+ T cell responses induced by a recombinant live malaria vaccine in mice.

BACKGROUND: Vaccine delivery into the skin has received renewed interest due to ease of access to the immune system and microvasculature, however the stratum corneum (SC), must be breached for successful vaccination. This has been achieved by removing the SC by abrasion or scarification or by delivering the vaccine intradermally (ID) with traditional needle-and-syringes or with long microneedle devices. Microneedle patch-based transdermal vaccine studies have predominantly focused on antibody induction by inactivated or subunit vaccines. Here, our principal aim is to determine if the design of a microneedle patch affects the CD8(+) T cell responses to a malaria antigen induced by a live vaccine. METHODOLOGY AND FINDINGS: Recombinant modified vaccinia virus Ankara (MVA) expressing a malaria antigen was percutaneously administered to mice using a range of silicon microneedle patches, termed ImmuPatch, that differed in microneedle height, density, patch area and total pore volume. We demonstrate that microneedle arrays that have small total pore volumes induce a significantly greater proportion of central memory T cells that vigorously expand to secondary immunization. Microneedle-mediated vaccine priming induced significantly greater T cell immunity post-boost and equivalent protection against malaria challenge compared to ID vaccination. Notably, unlike ID administration, ImmuPatch-mediated vaccination did not induce inflammatory responses at the site of immunization or in draining lymph nodes. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that the design of microneedle patches significantly influences the magnitude and memory of vaccine-induced CD8(+) T cell responses and can be optimised for the induction of desired immune responses. Furthermore, ImmuPatch-mediated delivery may be of benefit to reducing unwanted vaccine reactogenicity. In addition to the advantages of low cost and lack of pain, the development of optimised microneedle array designs for the induction of T cell responses by live vaccines aids the development of solutions to current obstacles of immunization programmes.

Vaccination in pregnancy.

The recent H1N1 influenza pandemic has highlighted the potential for viral infections to cause severe disease in mothers disproportionate to the general population and have deleterious effects on the fetus. Vaccines have been used in pregnant women for over 200 years. Current guidelines recommend vaccination with only inactivated virus due to potential risk to mother and fetus with live vaccine. The exception is during times of pandemic or biological weapons attack, when the risk of life-threatening disease outweighs the risk of vaccination. A paucity of data is available regarding actual risk and mechanisms of live viral vaccine transfer from mother to fetus. Pregnancy-induced changes to the maternal immune system, effects of maternal infection on neonatal immunity, and the role of the placenta in transmission of infection and passive immunity to the fetus are incompletely understood. The aim of this paper is to review available data pertaining to newer vaccines such as the pandemic H1N1 and HPV vaccines in pregnancy, the role of Fc receptors in active transport of immunoglobulin across the placenta, and cytokine activity during maternal infection and after vaccination. We will also discuss potential areas for future research.

In vivo biodistribution of a highly attenuated recombinant vesicular stomatitis virus expressing HIV-1 Gag following intramuscular, intranasal, or intravenous inoculation.

Recombinant vesicular stomatitis viruses (rVSVs) are being developed as potential HIV-1 vaccine candidates. To characterize the in vivo replication and dissemination of rVSV vectors in mice, high doses of a highly attenuated vector expressing HIV-1 Gag, rVSV(IN)-N4CT9-Gag1, and a prototypic reference virus, rVSV(IN)-HIVGag5, were delivered intramuscularly (IM), intranasally (IN), or intravenously (IV). We used quantitative, real-time RT-PCR (Q-PCR) and standard plaque assays to measure the temporal dissemination of these viruses to various tissues. Following IM inoculation, both viruses were detected primarily at the injection site as well as in draining lymph nodes; neither virus induced significant weight loss, pathologic signs, or evidence of neuroinvasion. In contrast, following IN inoculation, the prototypic virus was detected in all tissues tested and caused significant weight loss leading to death. IN administration of rVSV(IN)-N4CT9-Gag1 resulted in detection in numerous tissues (brain, lung, nasal turbinates, and lymph nodes) albeit in significantly reduced levels, which caused little or no weight loss nor any mortality. Following IV inoculation, both prototypic and attenuated viruses were detected by Q-PCR in all tissues tested. In contrast to the prototype, rVSV(IN)-N4CT9-Gag1 viral loads were significantly lower in all organs tested, and no infectious virus was detected in the brain following IV inoculation, despite the presence of viral RNA. These studies demonstrated significant differences in the biodistribution patterns of and the associated pathogenicity engendered by the prototypic and attenuated vectors in a highly susceptible host.

Replication kinetics of duck virus enteritis vaccine virus in ducklings immunized by the mucosal or systemic route using real-time quantitative PCR.

A chicken embryo-adapted duck enteritis virus (DEV) strain is the most widely used vaccine against duck virus enteritis (DVE) infection. The kinetics of attenuated DEV vaccine was examined in tissues of ducklings vaccinated by the mucosal or systemic route at 20 days of age and sampled regularly up to 60 days post-vaccination (p.v.). Significant numbers of virus genomes in the lymphoid and other parenchymatous organs were first detected at 60 min p.v., and subsequently rose to peak levels during 90 min to 1 day p.v. independent of the route of vaccine administration. The peak level of vaccine virus in the individual parenchymatous organs of subcutaneously immunized ducklings was significantly higher than that of orally or nasally immunized ducklings. The route of vaccine administration had significant effect on the initial tissue distribution of vaccine virus in respiratory and digestive tracts. Vaccine viruses spread to digestive tract and trachea tissues by mucosal route, i.e. oral and nasal administration, early than that by subcutaneous route. The rapid early increase of vaccine virus levels in all samples examined followed by a steady decline from 90 min to 6 days p.v. The real-time PCR analysis of a variety of tissues is significant for further investigation of the mechanism of vaccinal protection, and the optimization of vaccination regimes.

Varicella-zoster virus-specific immune responses in elderly recipients of a herpes zoster vaccine.

BACKGROUND: A double-blind, placebo-controlled trial that involved 38,546 subjects > or =60 years old demonstrated efficacy of a high-potency live-attenuated Oka/Merck varicella-zoster virus (VZV) vaccine. The trial included an immunology substudy to determine the relationship of VZV-specific immune responses to vaccination and clinical outcome. METHODS: The immunology substudy enrolled 1395 subjects at 2 sites where blood samples obtained prior to vaccination, at 6 weeks after vaccination, and at 1, 2, and 3 years thereafter were tested for VZV-specific cell-mediated immunity (VZV-CMI) by gamma-interferon ELISPOT and responder cell frequency assays and for VZV antibody by glycoprotein ELISA. RESULTS: VZV-CMI and VZV antibodies were significantly increased in vaccine recipients at 6 weeks after vaccination. The vaccine-induced increases in VZV-CMI persisted during the 3 years of follow-up, although their magnitude decreased over time. The magnitude of these VZV-specific immune responses was greater in subjects 60-69 years old than in subjects > or =70 years old. CONCLUSIONS: The zoster vaccine induced a significant increase in VZV-CMI and VZV antibody. The magnitude and duration of the boost in VZV-CMI in vaccine recipients and the relationship of this boost to age paralleled the clinical effects of the vaccine observed during the efficacy trial. These findings support the hypothesis that boosting VZV-CMI protects older adults against herpes zoster and postherpetic neuralgia.

Zoster vaccine live.

Herpes zoster is a neurocutaneous disease caused by the varicella-zoster virus and is associated with significant morbidity and long-term sequelae in older adults. Until recently, treatment options for these complications have been primarily targeted at disease state management and symptom relief. Zoster vaccine live is the first vaccine approved for the prevention of herpes zoster. The vaccine was approved by the United States Food and Drug Administration for adults aged 60 years or older. Results of the Shingles Prevention Study demonstrated that in older individuals, administration of zoster vaccine live reduces the burden of illness associated with herpes zoster by 61.1%, the frequency of herpes zoster pain and discomfort by 51.3%, and the frequency of postherpetic neuralgia by 66.5%. Overall, adverse events reported in clinical trials of zoster vaccine live were classified as mild. Events that occurred more frequently in zoster vaccine live recipients than in placebo recipients included injection site reactions, headache, respiratory infections, fever, flu syndrome, diarrhea, rhinitis, skin disorders, respiratory disorders, and asthenia. The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recently recommended universal vaccination for those 60 years of age and older, including those who have experienced previous episodes of shingles.

A live, attenuated recombinant West Nile virus vaccine.

West Nile (WN) virus is an important cause of febrile exanthem and encephalitis. Since it invaded the U.S. in 1999, >19,000 human cases have been reported. The threat of continued epidemics has spurred efforts to develop vaccines. ChimeriVax-WN02 is a live, attenuated recombinant vaccine constructed from an infectious clone of yellow fever (YF) 17D virus in which the premembrane and envelope genes of 17D have been replaced by the corresponding genes of WN virus. Preclinical tests in monkeys defined sites of vaccine virus replication in vivo. ChimeriVax-WN02 and YF 17D had similar biodistribution but different multiplication kinetics. Prominent sites of replication were skin and lymphoid tissues, generally sparing vital organs. Viruses were cleared from blood by day 7 and from tissues around day 14. In a clinical study, healthy adults were inoculated with 5.0 log(10) plaque-forming units (PFU) (n = 30) or 3.0 log10 PFU (n = 15) of ChimeriVax-WN02, commercial YF vaccine (YF-VAX, n = 5), or placebo (n = 30). The incidence of adverse events in subjects receiving the vaccine was similar to that in the placebo group. Transient viremia was detected in 42 of 45 (93%) of ChimeriVax-WN02 subjects, and four of five (80%) of YF-VAX subjects. All subjects developed neutralizing antibodies to WN or YF, respectively, and the majority developed specific T cell responses. ChimeriVax-WN02 rapidly elicits strong immune responses after a single dose, and is a promising candidate warranting further evaluation for prevention of WN disease.

Vaccination by aerosols: modulation of clearance mechanisms in the lung.

Inhalation and deposition within the the airways are the initial steps before pathogens of the respiratory tract are able to adhere and colonize their host. Once the microorganisms are deposited in the lung lining fluids they do not remain at the location where they first came in contact with the mucous membranes. It is long known that lung clearance mechanisms translocate all deposited particles. At least, most of them are swallowed and cleared via the gastrointestinal tract. Aerosol vaccination with inactivated or (recombinant) live bacteria has been shown to be an efficient way to induce local protection against lung diseases. It can be assumed that the local concentration of the vaccine and the deposition pattern of the vaccine within the lung limit the strength of a local or systemic immune response. The local concentration of airborne bacterial antigen necessary to initiate a mucosal immunity in the respiratory tract is known for a very few microorganisms. Bacterial survival, infectivity, deposition, and persistence characteristics have to be defined when aerosols are included in vaccination experiments.