Safety of live, attenuated oral vaccines in HIV-infected Zambian adults: oral vaccines in HIV

Recent development of oral vaccines (Review)

Oral immunization can elicit an effective immune response and immune tolerance to specific antigens. When compared with the traditional injection route, delivering antigens via the gastrointestinal mucosa offers superior immune effects and compliance, as well as simplicity and convenience, making it a more optimal route for immunization. At present, various oral vaccine delivery systems exist. Certain modified bacteria, such as Salmonella, Escherichia coli and particularly Lactobacillus, are considered promising carriers for oral vaccines. These carriers can significantly enhance immunization efficiency by actively replicating in the intestinal tract following oral administration. The present review provided a discussion of the main mechanisms of oral immunity and the research progress made in the field of oral vaccines. Additionally, it introduced the advantages and disadvantages of the currently more commonly administered injectable COVID-19 vaccines, alongside the latest advancements in this area. Furthermore, recent developments in oral vaccines are summarized, and their potential benefits and side effects are discussed.

Evaluation of medullary cytokine expression and clinical and laboratory aspects in severe human visceral leishmaniasis

BACKGROUND

Visceral leishmaniasis (VL) is a serious public health problem. The factors that can determine whether VL develops and progresses to severe form have not been fully identified, but a specific cellular immune response appears to play a key role. Therefore, understanding immunopathogenesis can be useful in preventing a serious clinical outcome.

MATERIALS AND METHODS

Bone marrow samples were collected from patients with severe VL (SVL) or non-severe VL (NSVL). Cytokine levels and parasitic load were analysed by RT-qPCR. There is a statistically significant difference in the leukocyte parameter in patients with SVL and NSVL compared with the control patients (p = .006 and p = .014, respectively).

RESULTS

Urea, alanine transaminase and albumin parameters had a significant difference p = .036, p = .039 and p = .017, respectively, between SVL and NSVL. Although high levels of IFN-γ, IL-10, IL-6 and TNF-α were present in all groups of individuals with VL, they were not statistically associated with severity. In patients with active VL, IFN-γ and IL-10 were associated, respectively, with a reduction and increase in the parasite load, strong and significant positive association between IFN-γ and IL-10 (rho = .627 and p = .003).

CONCLUSION

This study demonstrates that VL stimulates an non-dichotomized inflammatory response between Th1/Th2 and that bone marrow is an important tissue for immune regulation.

Health Considerations for HIV-Infected International Travelers

PURPOSE OF THE REVIEW

International travel continues to steadily increase, including leisure travel, travel to one's country of origin to visit friends and relatives, travel for service work, and business travel. Travelers with HIV may have an increased risk for travel-associated infections. The pre-travel medical consultation is an important means of assessing one's risk for travel-related health issues. The aim of this review is to provide an update on key health considerations for the HIV-infected traveler.

RECENT FINDINGS

Like all travelers, the HIV-infected traveler should adhere to behavioral precautions, including safety measures with food and water consumption, safe sexual practices, and arthropod bite avoidance. HIV is a risk factor for venous thromboembolism and patients should be educated regarding this risk. Most pre-travel vaccines are safe and immunogenic in HIV-infected individuals, though live vaccines should be avoided in patients with low CD4 counts. Malaria chemoprophylaxis is strongly recommended in patients with HIV traveling to endemic areas and no significant interactions exist between the commonly used prophylactic anti-malarial agents and anti-retroviral therapy (ART). Travelers with HIV, particularly those who are not on ART or who have low CD4 cell counts, may have increased risk for tuberculosis, malaria, enteric infections, visceral leishmaniasis, American trypanosomiasis, and endemic mycoses such as histoplasmosis, talaromycosis, and coccidioidomycosis. The immune status of the HIV-infected traveler should be assessed prior to travel along with the duration, itinerary, and activities planned during travel in order to carefully consider individual risk for travel-related health issues.

Retinoic acid elicits a coordinated expression of gut homing markers on T lymphocytes of Zambian men receiving oral Vivotif, but not Rotarix, Dukoral or OPVERO vaccines

•

ATRA increased vaccine specific IgA in gut secretions to Vivotif but not Dukoral or Rotarix.

•

ATRA increased α4β7 and CCR9 gut marker expression in a coordinated manner only when given simultaneously with Vivotif vaccine.

•

In individuals with coordinated gut marker expression Vivotif specific IgA increase was much stronger.

All-trans retinoic acid (ATRA) up-regulates, in laboratory animals, the expression of the gut homing markers α4β7 integrin and CCR9 on lymphocytes, increasing their gut tropism. Here, we show that, in healthy adult volunteers, ATRA induced an increase of these gut homing markers on T cells in vivo in a time dependent manner. The coordinated increase of α4β7 and CCR9 by ATRA was seen in 57% (12/21) of volunteers and only when given together with an oral Vivotif vaccine. When this coordinated response to ATRA and Vivotif vaccine was present, it was strongly correlated with the gut immunoglobulin A (IgA) specific response to vaccine LPS (ρ = 0.82; P = 0.02). Using RNA-Seq analysis of whole blood transcription, patients receiving ATRA and Vivotif in conjunction showed transcriptomic changes in immune-related pathways, particularly including interferon α/β signaling pathway, membrane-ECM interactions and immune hubs. These results suggest that exogenous ATRA can be used to manipulate responses to a subclass of oral vaccines, so far limited to a live attenuated Vivotif vaccine.

Safety of live vaccines on immunosuppressive or immunomodulatory therapy-a retrospective study in three Swiss Travel Clinics

BACKGROUND

Patients increasingly benefit from immunosuppressive/immunomodulatory medications for a range of conditions allowing them a lifestyle similar to healthy individuals, including travel. However, the administration of live vaccines to immunodeficient patients bears the risk of replication of the attenuated vaccine microorganism. Therefore, live vaccines are generally contraindicated on immunosuppression. Data on live vaccinations on immunosuppressive/immunomodulatory medication are scarce. We identified all travellers seeking pre-travel advice in three Swiss travel clinics with a live vaccine during immunosuppressive/immunomodulatory therapy to ascertain experienced side effects. A retrospective and multi-centre study design was chosen to increase the sample size.

METHODS

This study was conducted in the travel clinics of the University of Zurich; the Swiss TPH, Basel; and Geneva University Hospitals. Travellers on immunosuppressive/immunomodulatory therapy who received live vaccines [yellow fever vaccination (YFV), measles/mumps/rubella (MMR), varicella and/ or oral typhoid vaccination (OTV)] between 2008 and 2015 were identified and interviewed. A total of 60 age- and sex-matched controls (matched to Basel/Zurich travel clinics travellers) were included.

RESULTS

Overall, 197 patients were identified. And 116 patients (59%) and 60 controls were interviewed. YFV was administered 92 times, MMR 21 times, varicella 4 times and OTV 6 times to patients on immunosuppressive/immunomodulatory therapy. Most common medications were corticosteroids (n = 45), mesalazine (n = 28) and methotrexate (n = 19). Live vaccines were also administered on biological treatment, e.g. TNF-alpha inhibitors (n = 8). Systemic reactions were observed in 12.2% of the immunosuppressed vs 13.3% of controls; local reactions in 7.8% of the immunosuppressed vs 11.7% of controls. In controls, all reactions were mild/moderate. In the immunosuppressed, 2/21 severe reactions occurred: severe local pain on interferon-beta and severe muscle/joint pain on sulfasalazine.

CONCLUSION

Safety of live vaccines given to immunosuppressed patients cannot be concluded. However, it is re-assuring that in the examined patient groups no serious side effects or infections by the attenuated vaccine strain occurred.

Vaccinations for the HIV-Infected Adult: A Review of the Current Recommendations, Part II

Vaccination is a critical component for ensuring the ongoing health HIV-infected adults. Since this group may have reduced immune responses and shorter durations of protection post-vaccination, HIV-specific guidelines have been published. This review article provides a comprehensive discussion of the current guidelines and evidence-based data for vaccinating HIV-infected adults, including data on dosing schedules, immunogenicity studies, and safety. In the current paper, part II of the review, live vaccines, as well as vaccines for travelers and specific occupational groups, will be discussed.

Anti-microbial peptide gene expression during oral vaccination: analysis of a randomized controlled trial

We have observed previously that micronutrient supplementation ameliorated suppression of α‐defensin expression during diarrhoea. However, how interactions between anti‐microbial peptide (AMP) expression and diarrhoeal disease are altered by micronutrient supplementation remain unclear. Using oral vaccination as a model of intestinal infection, we measured changes in AMP expression during multiple micronutrient supplementation. In the first part, volunteers underwent duodenal jejunal biopsy before and at 1, 2, 4 or 7 days after administration of one of three live, attenuated oral vaccines against rotavirus, typhoid and enterotoxigenic Escherichia coli. In the second part, participants were randomized to receive a multiple micronutrient supplement or placebo for 6 weeks before undergoing intestinal biopsy, vaccination against typhoid and rebiopsy after 14 days. Expression of human alpha‐defensin (HD)5, HD6, hBD1, hBD2 and LL‐37 was measured by quantitative reverse transcription–polymerase chain reaction. Taken together, the bacterial vaccines, but not rotavirus vaccine, reduced HD5 expression (P = 0·02, signed‐rank test) and reduced LL‐37 expression in seven of the eight individuals whose biopsies had expression prevaccination (P = 0·03). hBD2 was not detected. In the controlled trial, HD5 and HD6 expression after vaccination was lower [median ratio 0·5, interquartile range (IQR) = 0·07–2·2 and 0·58, IQR = 0·13–2·3, respectively] than before vaccination. There was no significant effect detected of micronutrient supplementation on expression of HD5, HD6, hBD1 or LL‐37. We conclude that live attenuated bacterial vaccines, but not rotavirus vaccine, can reduce intestinal α‐defensins, and typhoid vaccine reduced LL‐37 expression. We found no evidence that micronutrient supplementation in the short term had any impact on anti‐microbial peptide expression.

European Society for Paediatric Infectious Diseases consensus recommendations for rotavirus vaccination in Europe: update 2014

The first evidence-based recommendations for rotavirus (RV) vaccination in Europe were prepared at the time of licensure of 2 live oral RV vaccines (Rotarix, GlaxoSmithKline Biologicals, and RotaTeq, Sanofi Pasteur MSD) in 2006 and published in 2008. Since then several countries in Europe and more globally have adopted universal RV vaccination of all healthy infants as part of their national immunization programs (NIPs). The experience from these NIPs has produced a wealth of post-introduction effectiveness data that, together with the evidence from prelicensure efficacy trials presented in the 2008 Recommendations, support the case of RV vaccination in Europe. The prelicensure safety trials of Rotarix and RotaTeq, each in populations of more than 60,000 infants, did not reveal risk of intussusception (IS), but postvaccination surveillance in several countries, particularly Australia and Mexico, has established that the risk of IS for both vaccines after the first dose might be between 1:50,000 and 1:80,000. Although it may be argued that the risk is acceptable vis-à-vis the great benefits of RV vaccination, this argument alone may not suffice, and every effort should be made to reduce the risk of IS. Considerable evidence, including postvaccination surveillance data from Germany, suggests that the risk of IS can be reduced by early administration of the first dose of oral RV vaccine. The previous European Society for Paediatric Infectious Diseases/European Society for Paediatric Gastroenterology, Hepatology and Nutrition recommendations held that the first dose of oral RV vaccine should be given between 6 and 12 weeks of age; this recommendation is sustained but with an emphasis toward the lower range of the recommended age, that is, preferably between 6 and 8 weeks of age. At the time of the earlier recommendations, experience of RV vaccination in premature infants and other special target groups was limited. It is now recommended with greater confidence than before that prematurely born infants should be vaccinated according to their calendar age as recommended for full-term infants. It is now strongly recommended that all HIV-infected or HIV-exposed infants should be vaccinated with oral RV vaccine. Although specific information on many immunodeficiencies is lacking, infants with known severe combined immunodeficiency should not receive live RV vaccine.

Live viral vaccines in immunocompromised patients

ABSTRACT: 

Live-attenuated viral vaccines (LAV) have been used safely for several decades in healthy individuals to protect against diseases with great success. In immunocompromised hosts their use is usually not recommended. We explore the use of currently available LAV, such as live-attenuated influenza, varicella–zoster virus, measles, mumps and rubella, oral polio, rotavirus, yellow fever virus vaccines, especially in patients with cancer, solid organ or hematopoietic stem cell transplant, HIV, and with acquired or congenital immunodeficiencies. Although evidence-based recommendations cannot currently be made, it is possible that LAV will be recommended in specific, well-defined situations in these immunocompromised patients in the future.

High dose multiple micronutrient supplementation improves villous morphology in environmental enteropathy without HIV enteropathy: results from a double-blind randomised placebo controlled trial in Zambian adults

BACKGROUND

Environmental enteropathy (EE) is an asymptomatic abnormality of small bowel structure and function, which may underlie vaccine inefficacy in the developing world. HIV infection co-exists in many of these populations. There is currently no effective treatment. We conducted a secondary analysis of a randomised controlled trial of high dose multiple micronutrient (MM) supplementation on small bowel architecture in EE in participants with or without HIV infection.

METHODS

In a double-blind parallel-group trial of the effect of MM on innate immune responses to oral vaccines, consenting Zambian adults were randomised to receive 6 weeks of 24 micronutrients as a daily capsule or placebo. HIV status was established after randomisation. Proximal jejunal biopsies were obtained after the supplementation period. Villous height, crypt depth, villous width, villous perimeter per 100 μm muscularis mucosa (a measure of epithelial surface area), and villous cross sectional area per 100 μm muscularis mucosa (a measure of villous compartment volume) were measured in orientated biopsy sections using semi-automated image analysis. Analysis was by intention to treat.

RESULTS

18 patients received MM and 20 placebo. 6/18 MM and 9/20 placebo patients had HIV. In HIV negative patients given MM compared to placebo, mean villous height was 24.0% greater (293.3 v. 236.6 μm; 95% CI of difference 17.7-95.9 μm; P = 0.006), mean villous area was 27.6% greater (27623 v. 21650 μm2/100 μm; 95% CI of difference 818-11130 μm2/100 μm; P = 0.03), and median villous perimeter was 29.7% greater (355.0 v. 273.7 μm/100 μm; 95% CI of difference 16.3-146.2 μm/100 μm; P = 0.003). There was no significant effect on crypt depth or villous width. No effect was observed in HIV positive patients. There were no adverse events attributable to MM.

CONCLUSIONS

MM improved small bowel villous height and absorptive area, but not crypt depth, in adults with EE without HIV. Nutritional intervention may therefore selectively influence villous compartment remodelling. In this small study, there was a clear difference in response depending on HIV status, suggesting that EE with superimposed HIV enteropathy may be a distinct pathophysiological condition.

Recombinant Salmonella Bacteria Vectoring HIV/AIDS Vaccines

HIV/AIDS is an important public health problem globally. An affordable, easy-to-deliver and protective HIV vaccine is therefore required to curb the pandemic from spreading further. Recombinant Salmonella bacteria can be harnessed to vector HIV antigens or DNA vaccines to the immune system for induction of specific protective immunity. These are capable of activating the innate, humoral and cellular immune responses at both mucosal and systemic compartments. Several studies have already demonstrated the utility of live recombinant Salmonella in delivering expressed foreign antigens as well as DNA vaccines to the host immune system. This review gives an overview of the studies in which recombinant Salmonella bacteria were used to vector HIV/AIDS antigens and DNA vaccines. Most of the recombinant Salmonella-based HIV/AIDS vaccines developed so far have only been tested in animals (mainly mice) and are yet to reach human trials.