Immunization in transplantation: review of the recent literature

Evidence for Microchimerism in Baboon Recipients of Pig Hearts

Xenotransplantation, like allotransplantation, is usually associated with microchimerism, i.e., the presence of cells from the donor in the recipient. Microchimerism was reported in first xenotransplantation trials in humans, as well as in most preclinical trials in nonhuman primates (for review, see Denner, Viruses 2023, 15, 190). When using pigs as xenotransplantation donors, their cells contain porcine endogenous retroviruses (PERVs) in their genome. This makes it difficult to discriminate between microchimerism and PERV infection of the recipient. Here, we demonstrate the appropriate virological methods to be used for the identification of microchimerism, first by screening for porcine cellular genes, and then how to detect infection of the host. Using porcine short interspersed nuclear sequences (SINEs), which have hundreds of thousands of copies in the pig genome, significantly increased the sensitivity of the screening for pig cells. Second, absence of PERV RNA demonstrated an absence of viral genomic RNA or expression as mRNA. Lastly, absence of antibodies against PERV proteins conclusively demonstrated an absence of a PERV infection. When applying these methods for analyzing baboons after pig heart transplantation, microchimerism could be demonstrated and infection excluded in all animals. These methods can be used in future clinical trials.

A randomized controlled trial of comparative effectiveness between the 2 dose and 3 dose regimens of hepatitis a vaccine in kidney transplant recipients

Hepatitis A virus (HAV) is able to cause a spectrum of illnesses ranging from no symptom to fulminant hepatitis which may lead to acute kidney injury. Although hepatitis A vaccine is recommended in non-immune solid organ transplant recipients who live in or travel to endemic areas, the standard 2-dose vaccination regimen demonstrated less favorable immunogenicity among these population. The 3-dose regimen showed higher response rate and immune durability in patients with human immunodeficiency virus. However, this strategy has never been studied in solid organ transplant recipients. A single-center, open-labeled, computer-based randomized controlled trial (RCT) with a 2:1 allocation ratio was conducted from August 2017 to December 2018. The study compared the seroconversion rate after receiving 2- or 3-dose regimen of hepatitis A vaccine at 0, 6 and 0, 1, 6 months, respectively, in non-immune kidney transplant recipients. A total of 401 adult kidney transplant recipients were screened for anti-HAV IgG and 285 subjects had positive results so the seroprevalence was 71.1%. Of 116 seronegative recipients, 93 (80.2%) completed vaccination; 60 and 33 participants completed 2- and 3-dose vaccination, respectively. The baseline characteristics were comparable between both groups. The seroconversion rate at 1 month after vaccination was 51.7% in the standard 2-dose regimen and 48.5% in the 3-dose regimen (p = 0.769). Overall, the seroconversion rate appeared to be associated with high estimated glomerular infiltration rate, high serum albumin, and low intensity immunosuppressive regimen. Seroconversion rate after hepatitis A vaccination in kidney transplant recipients was less favorable than healthy population. Three-dose regimen did not show superior benefit over the standard 2-dose regimen. Other strategies of immunization may increase immunogenicity among kidney transplant recipients.

Comparison of the immunogenicity of Dukoral® oral cholera vaccine between renal transplant recipients on either a calcineurin inhibitor or mycophenolate - A controlled trial

BACKGROUND

The evidence for recommendations regarding vaccination in solid organ transplant recipients is sparse. There is little data comparing vaccine responses between groups on different immunosuppressive drugs. This study was conducted to evaluate the antibody response to Dukoral® oral cholera vaccine in renal transplant recipients (RTR).

METHODS

In a single-center non-randomized controlled clinical trial, healthy volunteers (n = 21) and renal transplant recipients (n = 30) were vaccinated with the oral whole cell/recombinant B subunit cholera vaccine Dukoral® (Valneva Inc., Vienna, Austria). The RTR were stratified according to their maintenance immunosuppressive therapy: either prednisone and a calcineurin inhibitor (cyclosporine A or tacrolimus; P/CNI group; n = 15) or prednisone and mycophenolate (P/MMF group; n = 15). All volunteers ingested Dukoral® at baseline and at day 14. Serum samples were drawn at day 0 and day 21. The primary outcome was seroconversion, defined as either a 3-fold IgA serum titer increase in anti-cholera toxin B antibodies and/or a 4-fold rise in the serum vibriocidal titer.

RESULTS

Follow-up was complete. Seroconversion after vaccination was 57% (standard error, SE 9%) in RTR and 81% (SE 9%) in healthy controls (Relative Risk, RR 0.70; 95% CI 0.48-1.02). When stratified according to maintenance immunosuppression, the seroconversion rate was 67% (SE 12%) in the P/CNI group (RR compared with controls 0.82; 95% CI 0.55-1.25) and 47% (SE 13%) in the P/MMF group (RR compared with controls 0.58; 95% CI 0.32-1.03).

CONCLUSION

Adverse events were mild to moderate and transient. The response to Dukoral was weaker and the seroconversion rate was lower in renal transplant recipients than in healthy controls. In particular, those using mycophenolate had a poor response. Nevertheless, more than half of the transplant recipients seroconverted. Therefore oral vaccines should not be discarded as a potential tool for protection of solid organ transplant recipients. This trial is registered in clinicaltrials.gov under NCT01109914.

Pediatric kidney transplantation

Since first performed in 1954, kidney transplantation has evolved as the preferred long-term treatment of children with end stage renal disease (ESRD). The etiology of chronic kidney disease (CKD) and ESRD in children is broad and can be quite complicated, necessitating a multidisciplinary team to adequately care for these patients and their myriad needs. Precise surgical techniques and modern protocols for immunosuppression provide excellent long-term patient and graft survival. This article reviews the many etiologies of renal failure in the pediatric population focusing on those most commonly leading to the need for kidney transplantation. The processes of evaluation, kidney transplantation, short-term and long-term complications, as well as long-term outcomes are also reviewed.

Nasopharyngeal viral PCR in immunosuppressed patients and its association with virus detection in bronchoalveolar lavage by PCR

Background and objective

Pulmonary infiltrates are common in immunosuppressed patients. Bronchoscopy with bronchoalveolar lavage (BAL) is often used to evaluate their aetiology. However, it may not always be easily performed. Thus, alternative diagnostic strategies may be needed. There is limited data on the correlation of nasopharyngeal (NP) respiratory viral panel (RVP)‐PCR testing compared with BAL. We aimed to identify the predictive value of NP RVP‐PCR samples compared with samples obtained from BAL in immunosuppressed patients with pulmonary infiltrates.

Methods

We conducted an observational retrospective study of immunosuppressed adults who underwent bronchoscopy in the Pulmonary Department at the University of Rochester Medical Center between January 2011 and June 2016. We compared the positive and negative predictive values, sensitivity, specificity and false negative rate of NP RVP‐PCR and BAL RVP‐PCR, as well as identified clinical predictors of positive viral BAL RVP‐PCR.

Results

Eighty‐nine immunosuppressed patients had both NP and bronchoalveolar RVP‐PCR testing. Twenty‐one patients had NP(+)BAL(+) RVP‐PCR testing. Seven patients had false negative (NP(−)BAL(+)) RVP‐PCR testing. Three patients had NP(+)BAL(−) RVP‐PCR testing. The positive and negative predictive values of NP RVP‐PCR testing were 88% and 89%, respectively. Allogeneic bone marrow transplantation and testing performed in the winter and spring months were significantly associated with positive BAL RVP‐PCR (OR = 3.3 (1.19–9.12); OR = 4.62 (1.64–12.99), respectively).

Conclusion

NP RVP‐PCR testing has high concordance with testing performed on BAL samples. Repeat testing through BAL is beneficial when there is high concern for viral infection after initial NP RVP‐PCR testing is negative.

There are limited data on nasopharyngeal (NP) testing compared with bronchoscopy in immunosuppressed patients. NP PCR testing has a false negative rate of 8%, positive predictive value of 88% and negative predictive value of 89%.

http://onlinelibrary.wiley.com/doi/10.1111/resp.13061/abstract

Effect of the adjuvanted (AS03) A/H1N1 2009 pandemic influenza vaccine on the risk of rejection in solid organ transplant recipients in England: a self-controlled case series

OBJECTIVE

To assess the risk of solid organ transplant (SOT) rejection after vaccination with the adjuvanted (AS03) A/H1N1 2009 pandemic influenza vaccine Pandemrix.

DESIGN

Self-controlled case series (SCCS) in the UK Clinical Practice Research Datalink (CPRD) and its linked component of the Hospital Episodes Statistics (HES) inpatient database. Analyses were conducted using the SCCS method for censored, perturbed or curtailed post-event exposure.

PARTICIPANTS

Of the 184 transplant recipients having experienced at least one SOT rejection (liver, kidney, lung, heart or pancreas) during the study period from 1 October 2009 to 31 October 2010, 91 participants were included in the main analysis, of which 71 had been exposed to Pandemrix.

MAIN OUTCOME MEASURES

Occurrence of SOT rejection during risk (30 and 60 days after any Pandemrix dose) and control periods. Covariates in the CPRD included time since transplantation, seasonal influenza vaccination, bacterial and viral infections, previous SOT rejections and malignancies.

RESULTS

The relative incidence (RI) of rejection of any one of the five transplanted organs, adjusted for time since transplantation, was 1.05 (95% CI 0.52 to 2.14) and 0.80 (95% CI 0.42 to 1.50) within 30 and 60 days after vaccination, respectively. Similar estimates were observed for rejection of a kidney only, the most commonly transplanted organ (RI within 30 days after vaccination: 0.85 (95% CI 0.38 to 1.90)). Across various models and sensitivity analyses, RI estimates remained stable and within a consistent range around 1.0.

CONCLUSIONS

These results suggest a reassuring safety profile for Pandemrix with regard to the risk of rejection in SOT recipients in England and contribute to inform the benefit-risk of AS03-adjuvanted pandemic influenza vaccines in transplanted patients in the event of future pandemics.

TRIAL REGISTRATION NUMBER

NCT01715792.

Live virus vaccines in transplantation: friend or foe?

Solid organ and hematopoietic stem cell transplant recipients may be exposed to diseases which may be prevented through live attenuated virus vaccines (LAVV). Because of their immunosuppression, these diseases can lead to severe complications in transplant recipients. Despite increasing evidence regarding the safety and effectiveness of certain LAVV, these vaccines are still contraindicated for immunocompromised patients, such as transplant recipients. We review the available studies on LAVV, such as varicella zoster, measles-mumps-rubella, influenza, yellow fever, polio, and Japanese encephalitis vaccines in transplant patients. We discuss the current recommendations and the potential risks, as well as the expected benefits of LAVV immunization in this population.

Immunization after kidney transplantation-what is necessary and what is safe?

Many transplant recipients are not protected against vaccine-preventable illnesses, primarily because vaccination is still an underutilized tool both before and after transplantation. This missed opportunity for protection can result in substantial morbidity, graft loss and mortality. Immunization strategies should be formulated early in the course of renal disease to maximize the likelihood of vaccine-induced immunity, particularly as booster or secondary antibody responses are less affected by immune compromise than are primary or de novo antibody responses in naive vaccine recipients. However, live vaccines should be avoided in immunocompromised hosts. Although some concern has been raised regarding increased HLA sensitization after vaccination, no clinical data to suggest harm currently exists; overall, non-live vaccines seem to be immunogenic, protective and safe. In organ transplant recipients, some vaccines are indicated based on specific risk factors and certain vaccines, such as hepatitis B, can protect against donor-derived infection. Vaccines given to close contacts of renal transplant recipients can provide an additional layer of protection against infectious diseases. In this article, optimal vaccination of adult transplant recipients, including safety, efficacy, indication and timing, is reviewed.

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.