Determinants of vaccine immunity in the cohort of human immunodeficiency virus-infected children living in Switzerland

BACKGROUND: Human immunodeficiency virus (HIV)-infected children are at increased risk of infections caused by vaccine preventable pathogens, and specific immunization recommendations have been issued. METHODS: A prospective national multicenter study assessed how these recommendations are followed in Switzerland and how immunization history correlates with vaccine immunity. RESULTS: Among 87 HIV-infected children (mean age: 11.1 years) followed in the 5 Swiss university hospitals and 1 regional hospital, most (76%) had CD4 T cells >25%, were receiving highly active antiretroviral treatment (79%) and had undetectable viral load (60%). Immunization coverage was lower than in the general population and many lacked serum antibodies to vaccine-preventable pathogens, including measles (54%), varicella (39%), and hepatitis B (65%). The presence of vaccine antibodies correlated most significantly with having an up-to-date immunization history (P<0.05). An up-to-date immunization history was not related to age, immunologic stage, or viremia but to the referral medical center. CONCLUSIONS: All pediatricians in charge of HIV-infected children are urged to identify missing immunizations in this high-risk population.

Human coronavirus NL63 associated with lower respiratory tract symptoms in early life

Coronavirus NL63 has been identified as a new member of the coronavirus genus, but its role as a cause of respiratory disease needs to be established. We studied the first episode of lower respiratory tract symptoms in a cohort of healthy neonates. NL63 was identified in 6 (7%) of 82 cases and was as frequent as other coronaviruses (9%). NL63 was recovered at the onset of symptoms and was cleared within 3 weeks in half of the cases. Our data suggests that coronavirus NL63 causes lower respiratory tract symptoms and is acquired in early life.

JC virus-specific immune responses in human immunodeficiency virus type 1 patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a frequently fatal disease caused by uncontrolled polyomavirus JC (JCV) in severely immunodeficient patients. We investigated the JCV-specific cellular and humoral immunity in the Swiss HIV Cohort Study. We identified PML cases (n = 29), as well as three matched controls per case (n = 87), with prospectively cryopreserved peripheral blood mononuclear cells and plasma at diagnosis. Nested controls were matched according to age, gender, CD4(+) T-cell count, and decline. Survivors (n = 18) were defined as being alive for >1 year after diagnosis. Using gamma interferon enzyme-linked immunospot assays, we found that JCV-specific T-cell responses were lower in nonsurvivors than in their matched controls (P = 0.08), which was highly significant for laboratory- and histologically confirmed PML cases (P = 0.004). No difference was found between PML survivors and controls or for cytomegalovirus-specific T-cell responses. PML survivors showed significant increases in JCV-specific T cells (P = 0.04) and immunoglobulin G (IgG) responses (P = 0.005). IgG responses in survivors were positively correlated with CD4(+) T-cell counts (P = 0.049) and negatively with human immunodeficiency virus RNA loads (P = 0.03). We conclude that PML nonsurvivors had selectively impaired JCV-specific T-cell responses compared to CD4(+) T-cell-matched controls and failed to mount JCV-specific antibody responses. JCV-specific T-cell and IgG responses may serve as prognostic markers for patients at risk.

Divergent adaptation of hepatitis C virus genotypes 1 and 3 to human leukocyte antigen-restricted immune pressure

Many hepatitis C virus (HCV) infections worldwide are with the genotype 1 and 3 strains of the virus. Cellular immune responses are known to be important in the containment of HCV genotype 1 infection, and many genotype 1 T cell targets (epitopes) that are presented by host human leukocyte antigens (HLAs) have been identified. In contrast, there is almost no information known about the equivalent responses to genotype 3. Immune escape mechanisms used by HCV include the evolution of viral polymorphisms (adaptations) that abrogate this host-viral interaction. Evidence of HCV adaptation to HLA-restricted immune pressure on HCV can be observed at the population level as viral polymorphisms associated with specific HLA types. To evaluate the escape patterns of HCV genotypes 1 and 3, we assessed the associations between viral polymorphisms and specific HLA types from 187 individuals with genotype 1a and 136 individuals with genotype 3a infection. We identified 51 HLA-associated viral polymorphisms (32 for genotype 1a and 19 for genotype 3a). Of these putative viral adaptation sites, six fell within previously published epitopes. Only two HLA-associated viral polymorphisms were common to both genotypes. In the remaining sites with HLA-associated polymorphisms, there was either complete conservation or no significant HLA association with viral polymorphism in the alternative genotype. This study also highlights the diverse mechanisms by which viral evasion of immune responses may be achieved and the role of genotype variation in these processes. CONCLUSION: There is little overlap in HLA-associated polymorphisms in the nonstructural proteins of HCV for the two genotypes, implying differences in the cellular immune pressures acting on these viruses and different escape profiles. These findings have implications for future therapeutic strategies to combat HCV infection, including vaccine design.

Frequency of PRRS live vaccine virus (European and North American genotype) in vaccinated and non-vaccinated pigs submitted for respiratory tract diagnostics in North-Western Germany

The frequency of PRRSV corresponding to live vaccines and wild-type was determined in 902 pigs from North-Western Germany submitted for post-mortem examination. Overall, 18.5% of the samples were positive for the EU wild-type virus. EU genotype vaccine virus was detected in 1.3% and the NA genotype vaccine virus in 8.9% of all samples. The detection of the EU vaccine was significantly higher in pigs vaccinated with the corresponding vaccine (OR=9.4). Pigs vaccinated with NA genotype had significantly higher detection chances for the corresponding vaccine virus when compared to non-vaccinated animals (OR=3.34) animals, however, NA vaccine was also frequently detected in non-vaccinated pigs. Concluding, the dynamics of NA genotype vaccine and EU wild-type virus corresponds with studies on PRRSV spread in endemically infected herds. The potential of spontaneous spread of the NA genotype vaccine should be considered in the planning of eradication programs.

Risk Assessment of the Introduction of Porcine Reproductive and Respiratory Syndrome Virus via Boar Semen into Switzerland as an Example of a PRRSV-Free Country

Switzerland is currently porcine reproductive and respiratory syndrome virus (PRRSV) free, but semen imports from PRRSV-infected European countries are increasing. As the virus can be transmitted via semen, for example, when a free boar stud becomes infected, and the risk of its import in terms of PRRSV introduction is unknown, the annual probability to accidentally import the virus into Switzerland was estimated in a risk assessment. A quantitative stochastic model was set up with data comprised by import figures of 2010, interviews with boar stud owners and expert opinion. It resulted in an annual median number of 0.18 imported ejaculates (= imported semen doses from one collection from one donor) from PRRSV-infected boars. Hence, one infected ejaculate would be imported every 6 years and infect a mean of 10 sows. These results suggest that under current circumstances, there is a substantial risk of PRRSV introduction into Switzerland via imported boar semen and that measures to enhance safety of imports should be taken. The time from infection of a previously negative boar stud to its detection had the highest impact on the number of imported 'positive' ejaculates. Therefore, emphasis should be placed on PRRSV monitoring protocols in boar studs. Results indicated that a substantial increase in safety could only be achieved with much tighter sampling protocols than currently performed. Generally, the model could easily be customized for other applications like other countries or regions or even sow farms that want to estimate their risk when purchasing semen from a particular boar stud.

Experimental adaptation of wild-type canine distemper virus (CDV) to the human entry receptor CD150.

Canine distemper virus (CDV), a close relative of measles virus (MV), is widespread and well known for its broad host range. When the goal of measles eradication may be achieved, and when measles vaccination will be stopped, CDV might eventually cross the species barrier to humans and emerge as a new human pathogen. In order to get an impression how fast such alterations may occur, we characterized required adaptive mutations to the human entry receptors CD150 (SLAM) and nectin-4 as first step to infect human target cells. Recombinant wild-type CDV-A75/17(red) adapted quickly to growth in human H358 epithelial cells expressing human nectin-4. Sequencing of the viral attachment proteins (hemagglutinin, H, and fusion protein, F) genes revealed that no adaptive alteration was required to utilize human nectin-4. In contrast, the virus replicated only to low titres (10(2) pfu/ml) in Vero cells expressing human CD150 (Vero-hSLAM). After three passages using these cells virus was adapted to human CD150 and replicated to high titres (10(5) pfu/ml). Sequence analyses revealed that only one amino acid exchange in the H-protein at position 540 Asp→Gly (D540G) was required for functional adaptation to human CD150. Structural modelling suggests that the adaptive mutation D540G in H reflects the sequence alteration from canine to human CD150 at position 70 and 71 from Pro to Leu (P70L) and Gly to Glu (G71E), and compensates for the gain of a negative charge in the human CD150 molecule. Using this model system our data indicate that only a minimal alteration, in this case one adaptive mutation, is required for adaptation of CDV to the human entry receptors, and help to understand the molecular basis why this adaptive mutation occurs.

Distribution of human immunodeficiency virus (HIV) in the CNS of children with severe HIV encephalomyelopathy

The presence and distribution of human immunodeficiency virus (HIV) were examined in the CNS of two children with severe HIV encephalitis and myelitis. Using polymerase chain reaction-mediated DNA amplification and subsequent Southern analysis, proviral HIV gag sequences were identified in brain tissue of both patients. In situ hybridization using antisense oligonucleotide probes revealed abundant HIV gag and env/nef RNAs selectively in areas with histopathological evidence for HIV-induced tissue damage. The spinal cord of one patient exhibited a striking subpial accumulation of HIV RNAs strongly suggestive of a liquorigenic spread of the infection. HIV RNAs were typically associated with cells of the monocyte/macrophage lineage, as shown by a combined immunohistochemical and in situ hybridization procedure. The present study supports the view that the pattern and distribution of HIV-induced brain lesions is largely determined by the extent of focal HIV replication within the CNS.

Prognostic factors for advanced-stage human immunodeficiency virus-associated classical Hodgkin lymphoma treated with doxorubicin, bleomycin, vinblastine, and dacarbazine plus combined antiretroviral therapy: A multi-institutional retrospective study.

BACKGROUND The treatment and outcomes of patients with human immunodeficiency virus (HIV)-associated Hodgkin lymphoma (HL) continue to evolve. The International Prognostic Score (IPS) is used to predict the survival of patients with advanced-stage HL, but it has not been validated in patients with HIV infection. METHODS This was a multi-institutional, retrospective study of 229 patients with HIV-associated, advanced-stage, classical HL who received doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) plus combination antiretroviral therapy. Their clinical characteristics were presented descriptively, and multivariate analyses were performed to identify the factors that were predictive of response and prognostic of progression-free survival (PFS) and overall survival (OS). RESULTS The overall and complete response rates to ABVD in patients with HIV-associated HL were 91% and 83%, respectively. After a median follow-up of 5 years, the 5-year PFS and OS rates were 69% and 78%, respectively. In multivariate analyses, there was a trend toward an IPS score >3 as an adverse factor for PFS (hazard ratio [HR], 1.49; P=.15) and OS (HR, 1.84; P=.06). A cluster of differentiation 4 (CD4)-positive (T-helper) cell count <200 cells/μL was associated independently with both PFS (HR, 2.60; P=.002) and OS (HR, 2.04; P=.04). The CD4-positive cell count was associated with an increased incidence of death from other causes (HR, 2.64; P=.04) but not with death from HL-related causes (HR, 1.55; P=.32). CONCLUSIONS The current results indicate excellent response and survival rates in patients with HIV-associated, advanced-stage, classical HL who receive ABVD and combination antiretroviral therapy as well as the prognostic value of the CD4-positive cell count at the time of lymphoma diagnosis for PFS and OS. Cancer 2014. © 2014 American Cancer Society.

An Outbreak of Porcine Reproductive and Respiratory Syndrome Virus in Switzerland Following Import of Boar Semen

An outbreak of porcine reproductive and respiratory syndrome virus (PRRSV) occurred in November 2012 in Switzerland (CH), traditionally PRRSV-free. It was detected after a German boar stud informed a semen importer about the detection of PRRSV during routine monitoring. Tracing of semen deliveries revealed 26 Swiss sow herds that had used semen from this stud after its last negative routine monitoring and 62 further contact herds. All herds were put under movement restrictions and examined serologically and virologically. As a first measure, 59 sows from five herds that had previously been inseminated with suspicious semen were slaughtered and tested immediately. Investigations in the stud resulted in 8 positive boars with recent semen deliveries to CH (Seven with antibodies and virus, one with antibodies only). In one boar out of six tested, virus was detected in semen. Of the 59 slaughtered sows, five from three herds were virus-positive. In one herd, the virus had spread, and all pigs were slaughtered or non-marketable animals euthanized. In the remaining herds, no further infections were detected. After confirmatory testings in all herds 3 weeks after the first examination gave negative results, restrictions were lifted in January 2013, and Switzerland regained its PRRSV-free status. The events demonstrate that import of semen from non-PRRS-free countries - even from negative studs - poses a risk, because monitoring protocols in boar studs are often insufficient to timely detect an infection, and infections of sows/herds occur even with low numbers of semen doses. The outbreak was eradicated successfully mainly due to the high disease awareness of the importer and because immediate actions were taken before clinical or laboratory diagnosis of a single case in the country was made. To minimize the risk of an introduction of PRRSV in the future, stricter import guidelines for boar semen have been implemented.

Increased mortality after a first myocardial infarction in human immunodeficiency virus-infected patients; a nested cohort study.

AIMS HIV infection may be associated with an increased recurrence rate of myocardial infarction. Our aim was to determine whether HIV infection is a risk factor for worse outcomes in patients with coronaray artery disease. METHODS We compared data aggregated from two ongoing cohorts: (i) the Acute Myocardial Infarction in Switzerland (AMIS) registry, which includes patients with acute myocardial infarction (AMI), and (ii) the Swiss HIV Cohort Study (SHCS), a prospective registry of HIV-positive (HIV+) patients. We included all patients who survived an incident AMI occurring on or after 1st January 2005. Our primary outcome measure was all-cause mortality at one year; secondary outcomes included AMI recurrence and cardiovascular-related hospitalisations. Comparisons used Cox and logistic regression analyses, respectively. RESULTS There were 133 HIV+, (SHCS) and 5,328 HIV-negative [HIV-] (AMIS) individuals with incident AMI. In the SHCS and AMIS registries, patients were predominantly male (72% and 85% male, respectively), with a median age of 51 years (interquartile range [IQR] 46-57) and 64 years (IQR 55-74), respectively. Nearly all (90%) of HIV+ individuals were on successful antiretroviral therapy. During the first year of follow-up, 5 (3.6%) HIV+ and 135 (2.5%) HIV- individuals died. At one year, HIV+ status after adjustment for age, sex, calendar year of AMI, smoking status, hypertension and diabetes was associated with a higher risk of death (HR 4.42, 95% CI 1.73-11.27). There were no significant differences in recurrent AMIs (4 [3.0%] HIV+ and 146 [3.0%] HIV- individuals, OR 1.16, 95% CI 0.41-3.27) or in hospitalization rates (OR 0.68 [95% CI 0.42-1.11]). CONCLUSIONS HIV infection was associated with a significantly increased risk of all-cause mortality one year after incident AMI.

Proteome-wide screening of the European porcine reproductive and respiratory syndrome virus reveals a broad range of T cell antigen reactivity.

The porcine reproductive and respiratory syndrome virus (PRRSV) is a rapidly evolving and diversifying pathogen necessitating the development of improved vaccines. Immunity to PRRSV is not well understood although there are data suggesting that virus-specific T cell IFN-γ responses play an important role. We therefore aimed to better characterise the T cell response to genotype 1 (European) PRRSV by utilising a synthetic peptide library spanning the entire proteome and a small cohort of pigs rendered immune to PRRSV-1 Olot/91 by repeated experimental infection. Using an IFN-γ ELISpot assay as a read-out, we were able to identify 9 antigenic regions on 5 of the viral proteins and determine the corresponding responder T cell phenotype. The diversity of the IFN-γ response to PRRSV proteins suggests that antigenic regions are scattered throughout the proteome and no one single antigen dominates the T cell response. To address the identification of well-conserved T cell antigens, we subsequently screened groups of pigs infected with a closely related avirulent PRRSV-1 strain (Lelystad) and a divergent virulent subtype 3 strain (SU1-Bel). Whilst T cell responses from both groups were observed against many of the antigens identified in the first study, animals infected with the SU1-Bel strain showed the greatest response against peptides representing the non-structural protein 5. The proteome-wide peptide library screening method used here, as well as the antigens identified, warrant further evaluation in the context of next generation vaccine development.

Cryptococcal Antigenemia in Immunocompromised Human Immunodeficiency Virus Patients in Rural Tanzania: A Preventable Cause of Early Mortality

Background.  Cryptococcal meningitis is a leading cause of death in people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome. The World Health Organizations recommends pre-antiretroviral treatment (ART) cryptococcal antigen (CRAG) screening in persons with CD4 below 100 cells/µL. We assessed the prevalence and outcome of cryptococcal antigenemia in rural southern Tanzania. Methods.  We conducted a retrospective study including all ART-naive adults with CD4 <150 cells/µL prospectively enrolled in the Kilombero and Ulanga Antiretroviral Cohort between 2008 and 2012. Cryptococcal antigen was assessed in cryopreserved pre-ART plasma. Cox regression estimated the composite outcome of death or loss to follow-up (LFU) by CRAG status and fluconazole use. Results.  Of 750 ART-naive adults, 28 (3.7%) were CRAG-positive, corresponding to a prevalence of 4.4% (23 of 520) in CD4 <100 and 2.2% (5 of 230) in CD4 100-150 cells/µL. Within 1 year, 75% (21 of 28) of CRAG-positive and 42% (302 of 722) of CRAG-negative patients were dead or LFU (P<.001), with no differences across CD4 strata. Cryptococcal antigen positivity was an independent predictor of death or LFU after adjusting for relevant confounders (hazard ratio [HR], 2.50; 95% confidence interval [CI], 1.29-4.83; P = .006). Cryptococcal meningitis occurred in 39% (11 of 28) of CRAG-positive patients, with similar retention-in-care regardless of meningitis diagnosis (P = .8). Cryptococcal antigen titer >1:160 was associated with meningitis development (odds ratio, 4.83; 95% CI, 1.24-8.41; P = .008). Fluconazole receipt decreased death or LFU in CRAG-positive patients (HR, 0.18; 95% CI, .04-.78; P = .022). Conclusions.  Cryptococcal antigenemia predicted mortality or LFU among ART-naive HIV-infected persons with CD4 <150 cells/µL, and fluconazole increased survival or retention-in-care, suggesting that targeted pre-ART CRAG screening may decrease early mortality or LFU. A CRAG screening threshold of CD4 <100 cells/µL missed 18% of CRAG-positive patients, suggesting guidelines should consider a higher threshold.