Immunogenicity and efficacy of heterologous ChAdOx1-BNT162b2 vaccination

Following severe adverse reactions to the AstraZeneca ChAdOx1-S-nCoV-19 vaccine1,2, European health authorities recommended that patients under the age of 55 years who received one dose of ChAdOx1-S-nCoV-19 receive a second dose of the Pfizer BNT162b2 vaccine as a booster. However, the effectiveness and the immunogenicity of this vaccination regimen have not been formally tested. Here we show that the heterologous ChAdOx1-S-nCoV-19 and BNT162b2 combination confers better protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than the homologous BNT162b2 and BNT162b2 combination in a real-world observational study of healthcare workers (n = 13,121). To understand the underlying mechanism, we conducted a longitudinal survey of the anti-spike immunity conferred by each vaccine combination. Both combinations induced strong anti-spike antibody responses, but sera from heterologous vaccinated individuals displayed a stronger neutralizing activity regardless of the SARS-CoV-2 variant. This enhanced neutralizing potential correlated with increased frequencies of switched and activated memory B cells that recognize the SARS-CoV-2 receptor binding domain. The ChAdOx1-S-nCoV-19 vaccine induced a weaker IgG response but a stronger T cell response than the BNT162b2 vaccine after the priming dose, which could explain the complementarity of both vaccines when used in combination. The heterologous vaccination regimen could therefore be particularly suitable for immunocompromised individuals.

Characteristics of autoantibodies to human interferon in a patient with varicella-zoster disease

A patient with varicella-zoster disease was found to have antibodies to human interferon. These antibodies included all IgG subclasses, showed a high combined affinity (average dissociation constant, 10(-11)M), and were present in serum at a concentration of 10(-9)M. The antibodies neutralized the activity of a series of human alpha-interferons prepared from recombinant DNA as well as that of naturally occurring mixtures of alpha-type interferon prepared by viral stimulation of human cells. Examination of the patient's lymphoid cells revealed normal production of interferon and normal expression of interferon receptors. Interferon from the patient's cells was neutralized by her serum. The neutralizing capacity of this serum was analyzed with regard to levels of interferon previously detected in patients with varicella-zoster infections.

Health care-associated hepatitis C virus infection

Hepatitis C virus (HCV) is a blood-borne pathogen that has a worldwide distribution and infects millions of people. Care-associated HCV infections represented a huge part of hepatitis C burden in the past via contaminated blood and unsafe injections and continue to be a serious problem of public health. The present review proposes a panorama of health care-associated HCV infections via the three mode of contamination that have been identified: (1) infected patient to non-infected patient; (2) infected patient to non-infected health care worker (HCW); and (3) infected HCW to non infected patient. For each condition, the circumstances of contamination are described together with the means to prevent them. As a whole, the more important risk is represented by unsafe practices regarding injections, notably with the improper use of multidose vials used for multiple patients. The questions of occupational exposures and infected HCWs are also discussed. In terms of prevention and surveillance, the main arm for combating care-associated HCV infections is the implementation of standard precautions in all the fields of cares, with training programs and audits to verify their good application. HCWs must be sensitized to the risk of blood-borne pathogens, notably by the use of safety devices for injections and good hygiene practices in the operating theatre and in all the invasive procedures. The providers performing exposed-prone procedures must monitor their HCV serology regularly in order to detect early any primary infection and to treat it without delay. With the need to stay vigilant because HCV infection is often a hidden risk, it can be hoped that the number of people infected by HCV via health care will decrease very significantly in the next years.

Comparative evaluation of immunoglobulin M neutralizing antibody response in acute-phase sera and virus isolation for the routine diagnosis of enterovirus infection

A total of 314 patients exhibiting symptoms consistent with a viral disease provided, during the early stage of hospitalization, at least one specimen from a peripheral site (throat or stools or both) and a serum specimen in order to evaluate the neutralizing immunoglobulin M (IgM) antibody response in acute-phase serum in comparison with virus isolation for the rapid diagnosis of enterovirus (EV) infection. IgM antibodies were fractionated by ion-exchange chromatography and tested by seroneutralization against the various types of EV that have been recently circulating. A total of 189 patients (60%) were negative, and 21 (7%) were positive by both methods; in 51 patients (16%), a virus was isolated without IgM antibody response; 53 patients (17%) showed the opposite pattern. In all age groups except for children under 6 months, the frequency of positive results was higher with IgM serology than with virus isolation (27 and 22%, respectively). Apart from meningitis, for which isolation was more efficient, the other clinical conditions were associated with similar percentages of positivity by both methods. Regarding the 21 cases with positive results by the two techniques, the same serotype was detected in 9 cases and different serotypes were detected in 12, suggesting crossreactivities. Thus, IgM neutralizing antibody response on acute-phase serum appears to be of limited value in the rapid diagnosis of acute EV infection but may prove useful for the investigation of the wide range of chronic diseases associated with EV.

Is transfusion-transmitted dengue fever a potential public health threat?

Dengue is an arboviruses due to single-stranded enveloped ribonucleic acid viruses, named dengue viruses (DENV), that include four serotypes and are mainly transmitted via the bite of mosquitoes of the genus Aedes (A. aegypti and A. albopictus). The distribution of the disease was historically limited to intertropical areas; however, during the last thirty years, the perimeter of the disease extended considerably and temperate areas are now at risk of outbreaks. The present global burden of dengue is considerable: 2.5 billion people over more than 100 countries are concerned; 50 to 100 million infections occur every year, with a number of fatal cases of approximately 20000. Although frequently asymptomatic or limited to a mild fever, dengue is responsible for severe cases mainly consecutive to the occurrence of hemorrhagic complications that can lead to shock and death, notably in children from poor-resource settings. The place of DENV as a transfusion-transmitted pathogen has been recognized only in 2008. At the present time, only five cases of transfusion-transmitted dengue, including one case of dengue hemorrhagic fever, have been formerly documented. This review provides a general overview of dengue, its viruses and their vectors. It replaces the disease in the context of other viral diseases transmitted by arthropods. It discusses the threat of dengue on the supply of blood products in endemic and non endemic areas. Finally, it describes the specific and non specific measures available for improving the security of blood products with regards to this emerging risk. Interestingly, in 2009, the American Association of Blood Banks placed DENV in the highest category of emerging infectious agents for their potential impact on transfusion recipient safety for the next years in North America.

[Emergent viral threats in blood transfusion]

During the last 20 years, the safety of blood products increased dramatically with regard to the infectious risk and notably to that represented by retroviruses (HIV and HTLV) and hepatitis B and C viruses. The aim of this review is to identify the residual and emergent viral threats that could be responsible for the occurring of new contaminations in the receivers of blood products. Beside many other viruses (HHV-8, erythrovirus B19, hepatitis A and E viruses...), a special attention has been paid to emerging arbovirus diseases (West Nile virus infection, dengue, chikungunya) that threaten to occur in the French metropolitan area following the implantation in Europe of the mosquito Aedes albopictus, the main vector of dengue and chikungunya in temperate regions. Another blood-linked risk, notably in United Kingdom and France, is the prion agent responsible for the variant form of the Creutzfeldt-Jakob disease. The review is concluded by a brief overview of the measures aimed to control these emergences, including the exclusion of at-risk donors, the diagnostic tests able to detect a specific agent, the leukocyte reduction of labile blood products, and the physical or chemical treatments aiming the nonspecific inactivation of infectious agents potentially present in blood without impairing significantly the physiological properties of blood compounds. The ability to control prospectively the new viral risks linked to blood products is a challenge for the preservation of the confidence of both clinicians and receivers in the safety of blood transfusion.

Role of sex and early interferon production in the susceptibility of mice to encephalomyocarditis virus

Adult female Swiss mice showed a greater resistance to intraperitoneal (i.p.) infection with encephalomyocarditis virus (EMCV) than male mice. This difference was not observed in weanling mice, in castrated adult mice or in adult mice injected intracerebrally. Administration of antibody to mouse interferon alpha/beta enhanced the virulence of EMCV for both sexes and no difference was then observed in susceptibility between male and female mice. Six h after EMCV infection, serum interferon titres were higher in adult female mice than in male mice. There was a close correlation between the early serum interferon titre (at 6 h) and survival of EMCV-infected mice. No differences in serum interferon titres were observed between male or female weanling mice or castrated adult mice. Potent preparations of exogenous interferon provided the same degree of protection against EMCV infection in male and female mice. We conclude that the more marked early interferon response of female mice to i.p. EMCV infection is one of the important factors underlying the differential susceptibility to EMCV. It is possible that the interferon system is also involved in the reported greater prevalence of picornavirus infections of men compared with women.

Rapid diagnosis of echovirus 33 infection by neutralizing specific IgM antibody

In 1982, we isolated 20 strains of echovirus type 33 (EV33) from 18 patients. We studied the humoral response to EV33 of 2,437 subjects from whom at least one serum was available during the same year. In 388 subjects with the neutralizing antibody level at 64 or more, we assayed the EV33 IgM antibodies by seroneutralization test after fractionation of sera by ion exchange chromatography. One hundred ninety-five subjects (8.0%) had a high titre (greater than or equal to 32) of EV33 IgM antibodies, which was considered as evidence of recent infection. The EV33-positive IgM fractions were assayed against five other enteroviruses. Sixty percent of the IgM fractions did not cross-react with any of the five serotypes, 8.7% cross-reacted with at least one serotype but with predominant EV33 IgM response, and 31.3% had an equivalent or greater amount of non-EV33 IgM antibodies; the type specificity of the assay was directly related to the age of the subjects. These findings suggest that determination of neutralizing specific IgM antibody is a sensitive and rapid test for the diagnosis of enterovirus infections, especially in young people.

Structure, genomic organization, replication and variability of hepatitis C virus

Hepatitis C virus (HCV) is an enveloped, single-stranded RNA virus that has been classified in the Flaviviridae family. The genome of 9400 nucleotides comprises two non-coding regions in 5' and 3' flanking a large reading frame which codes for a polyprotein of 3000 amino acids; this polyprotein is further cleaved into structural (C, E1, E2) and non-structural (NS1, NS2, NS3, NS4, NS5) proteins. The positive RNA acts as a cap-independent messenger; the transcription is mediated by the NS5 RNA polymerase. After the maturation step, the virion is liberated by budding through the cytoplasmic membrane. As for many other RNA viruses, the HCV genome exhibits a high degree of variability, especially in the E2/NS1, E1, NS3 and NS5b regions. Conversely the 5' non-coding region is highly conserved, at least in part, and can be used for diagnostic purposes by PCR technique. Six genotypes of HCV have already been reported, numbered from 1 to 6 in Simmonds' classification. The same genotype can be divided into subtypes (for instance, genotype 1 comprises three subtypes: 1a, 1b and 1c). Various minor variants of the same strain, called quasispecies, are commonly present in the blood of the same patient. Strains of genotype 1b--which is the most widespread worldwide--are correlated with more severe clinical manifestations, greater viral loads and lower response to interferon treatment. The high variability of the HCV genome contributes greatly to the difficulty of designing potent vaccines.

Is there a relationship between malnutrition, inflammation, and post-vaccinal antibody response to influenza viruses in the elderly?

This study was designed to explore the relationship between malnutrition, inflammation, and the specific antibody response after influenza vaccination in the elderly. Eighty-two aged subjects, immunized annually against influenza with a trivalent inactivated vaccine, were evaluated for 9 protein markers (albumin, thyroxin-binding prealbumin, transferrin, immunoglobulins (Ig) G, M, and A, orosomucoid, haptoglobin, and C reactive protein) and for their antibody response to influenza viruses in comparison to 29 younger adults who received the same vaccine and 21 unvaccinated adults. IgM and nutritional markers were significantly reduced in the aged as compared to controls, while the opposite pattern was seen for IgA and inflammatory markers. No difference was observed between the elderly and the controls with regard to the antibody response to influenza virus after vaccination. Reciprocally, influenza immunization had no influence on the levels of the protein variables. These results suggest that the protein status does not play an important role in the antibody response to influenza vaccination in the elderly, a fact which could be related to the slight involvement of cellular immunity in the defense against influenza reinfection.

Detection of immunoglobulin G, M, and A antibodies to enterovirus structural proteins by immunoblot technique in echovirus type 4-infected patients

Paired serum specimens from 24 patients with echovirus (EV) type 4 infection by virus isolation were tested by the immunoblot technique for the presence of IgG, IgM, and IgA antibodies to EV4 structural proteins. Single sera from 20 patients without neutralizing enterovirus IgM were used as controls. All the sera from EV4-infected patients had IgG antibodies to VP1 of EV4 but also 13 out of the 20 controls. 23 out of 24 EV4-infected patients elicited IgM and IgA specific antibodies to VP1, a pattern highly significant as compared with controls (3/20 for IgM and 8/20 for IgA). In 16 out of the 24 EV4-infected patients, the IgM antibodies were also directed against VP2 (versus 2 out of 20 in the control group). Anti-VP2 IgA were detected in 4 out of the 24 EV4 patients (versus 0 in controls). The 24 paired sera from EV4-infected subjects were also tested by immunoblot technique against three other enteroviruses: EV21, coxsackievirus A9 and poliovirus 1. Cross-reactivities were observed to a large extent against VP1 and VP2 proteins with the three classes of antibodies. These results confirm the data of previous studies on the reactivity of IgM antibodies to various structural proteins that IgG antibodies react exclusively to VP1. Furthermore, this study demonstrates the occurrence of circulating IgA antibodies directed to VP1 and sometimes VP2 in the course of enterovirus infection. The potential interest of this latter finding for diagnosis requires further investigation.

[New viral risks in blood transfusion by 2016]

Viral safety remains a major concern in transfusion of blood products. Over years, the control measures applied to blood products were made more and more sophisticated; however, the number of infectious agents, and notably of viruses, that can be transmitted by transfusion is increasing continuously. The aim of this review paper is to actualize that published in the same journal by the same authors in 2011 with more details on some of actual vs virtual viral threats that were identified recently in the field of blood transfusion. The main subjects that are covered successively concern the transmission via transfusion of hepatitis E virus, the frequency of transfusion transmitted arboviruses, transfusion at the time of the Ebola epidemics in West Africa, the debated role of Marseillevirus (giant viruses infecting amoebae and suspected to infect human blood latently), and, finally, the recent report of the identification in blood donors of a new member of the Flaviviridae family. The addition of these new viral risks to those already identified-partially controlled or not-pleads for the urgent need to move forward to considering inactivation of infectious agents in blood products.

Current and future microbicide approaches aimed at preventing HIV infection in women

Women from developing countries, in which the prevalence of HIV infection is very high, are at risk of becoming infected without having the possibility of personally controlling this risk. Therefore, there is an urgent need to develop anti-HIV vaginal microbicide strategies. This review considers the modes of entry of HIV through the mucosa of the female genital tract, the different classes of vaginal microbicide compounds, the mode of delivery of these drugs, the aims and methods of in vitro and animal experiments at the preclinical stage, the results of the Phase III trials conducted in different countries, including the ongoing assays, and the future orientations for the next 5 years with a discussion relative to antiviral resistance, combination strategies and development of new-generation compounds.

Commercial monoclonal antibodies for rapid detection of respiratory syncytial virus by direct immunofluorescence

A commercially available direct immunofluorescence (IF) test using a reagent consisting of a pool of two monoclonal antibodies against selected surface and internal proteins of respiratory syncytial virus (RSV) was evaluated in comparison with the indirect IF technique using a commercial bovine anti-RSV hyperimmune serum for the rapid detection of RSV in nasopharyngeal aspirates from 228 hospitalized children. Overall agreement between the two IF methods was 95%. The direct IF test was quicker to perform and easier to interpret than the indirect IF test.

Arboviral Risk Associated with Solid Organ and Hematopoietic Stem Cell Grafts: The Prophylactic Answers Proposed by the French High Council of Public Health in a National Context

Diseases caused by arboviruses are on the increase worldwide. In addition to arthropod bites, most arboviruses can be transmitted via accessory routes. Products of human origin (labile blood products, solid organs, hematopoietic stem cells, tissues) present a risk of contamination for the recipient if the donation is made when the donor is viremic. Mainland France and its overseas territories are exposed to a complex array of imported and endemic arboviruses, which differ according to their respective location. This narrative review describes the risks of acquiring certain arboviral diseases from human products, mainly solid organs and hematopoietic stem cells, in the French context. The main risks considered in this study are infections by West Nile virus, dengue virus, and tick-borne encephalitis virus. The ancillary risks represented by Usutu virus infection, chikungunya, and Zika are also addressed more briefly. For each disease, the guidelines issued by the French High Council of Public Health, which is responsible for mitigating the risks associated with products of human origin and for supporting public health policy decisions, are briefly outlined. This review highlights the need for a "One Health" approach and to standardize recommendations at the international level in areas with the same viral epidemiology.

[Gestion of arboviral alerts: Experience feedback from the Secproch working group of the French "Haut Conseil de la santé publique" (2019-2021)]

The Secproch working group (for "sécurité des produits issus du corps humain") was created in 2019 within the « Haut Conseil de la santé publique » (HCSP) for addressing all the questions related to labile blood products, organs, tissues, cells (OTC) and gametes issued from human body. It is notably in charge of the management of alerts regarding arbovirus infections. These infections due to arthropod-transmitted viruses are responsible for emergence and reemergence, notably in the context of global warming. This review relates the alerts taken into consideration by the Secproch group between 2019 and 2021 following three pathologies due to Flaviviridae : dengue, West Nile virus (WNV) infection and tick-borne encephalitis (TBE). The dengue alerts have occurred in French Indies where the virus is endemic/epidemic, Reunion Island where the population was naïve until 2018 towards the virus, and the metropole where foci of autochthonous cases are observed sporadically. The WNV infection was responsible of both human and equine cases in 2019 in the South of France but with intensity much less than in 2018. At last, the TBE virus was at the origin of a cluster of about 40 cases in the Ain department following a contamination by crude non-pasteurized goat cheese. This review offers the opportunity to reevaluate the risks linked to these three viruses through blood products and organs/tissues/cells and to precise the means recommended by HCSP to secure these products.

[Immunization against interferon in man]

We have summarized 14 human cases with antibodies to interferon (anti-IFN) reported in the literature. In 4 cases, the patients developed auto-antibodies without any injection of exogenous interferon (IFN). In most cases, antibodies were directed against alpha IFN (13/14) and especially against recombinant alpha 2 IFN (8/14). When tested, antibodies to IFN were always IgG. In a few subjects, the IFN system has been studied more completely with the following results: the competent cells are able, after induction, to produce IFN; the endogenous IFN is neutralized by the antibodies to IFN; the antibodies to IFN are able to inhibit the interaction of IFN with its specific cellular receptors. Clinically, the raising of an anti-IFN immunization does not seem to impair the antiviral or antitumoral effects of IFN. These data can be related to the relative low neutralizing titres of antibodies to IFN with regard to levels of IFN produced at the site of the viral infection. We discuss the putative benefit of antibodies on the availability of circulating IFN and the possible role of antibodies to IFN in autoimmune diseases.

[The latest on enteroviruses in human pathology]

Enteroviruses are small RNA viruses belonging to the Picornaviridae family. At least 65 serotypes have been described, including polioviruses, coxsackieviruses A and B, echoviruses and unclassified enteroviruses. Because of the absence of envelope they are relatively resistant to physical and chemical agents. They are mainly transmitted by the oral-fecal mode, but respiratory and mucosal transmissions are also possible. In humans, enteroviruses have been involved in miscellaneous acute infections and more recently in persistent infections (chronic meningoencephalitis in agammaglobulinemic patients, post-polio syndrome, chronic myocarditis and dilated cardiomyopathy, insulin-dependent diabetes mellitus...). Hypotheses in the relation between enterovirus persistence and chronic infections are formulated. The virological diagnosis of enterovirus infections is discussed, with a special focus on genomic application techniques (PCR) that are renewing the interest for this family of viruses in clinical pathology. If the role of enteroviruses in chronic pathologies is confirmed, the development of new therapeutic approaches (including vaccines and antiviral agents) will be needed.