Microscopic visualization of lung sections from a mouse model of house dust mite asthma, with hematoxylin and eosin staining showing bronchial obstruction and white blood cell infiltration around the bronchi in the unvaccinated group (left) but not in the vaccinated group (right). © Dr Eva Conde.

To combat allergic asthma, which affects millions of people worldwide, scientists from Inserm, CNRS and Université Toulouse III-Paul Sabatier at the Infinity laboratory[1], Institut Pasteur and French company NEOVACS are developing and testing a new vaccine. In their previous study, the teams had shown it to be effective in producing antibodies capable of neutralizing human immune proteins that play a key role in triggering allergic asthma, cytokines IL-4 and IL-13. The results, published in Allergy, pave the way for the organization of a clinical trial.

Asthma is a chronic disease that affects around 4 million people in France and 340 million worldwide. Allergic asthma, which accounts for around 50% of asthma cases, is characterized by inflammation of the bronchial tubes and respiratory discomfort caused by the inhalation of allergens, most often dust mites.

This exposure to dust mites and other allergens triggers the overproduction of antibodies called immunoglobulin E (IgE) and proteins called type 2 cytokines (particularly interleukin-4 (IL-4) and IL-13) in the airways. This phenomenon leads to a cascade of reactions resulting in hyperresponsiveness of the respiratory tract, overproduction of mucus, and eosinophilia (when there are too many eosinophils, a type of white blood cell, in the airways).

At present, inhaled corticosteroids are the gold standard for controlling asthma. However, in the case of severe allergic asthma, this treatment is not always sufficient. Therapeutic monoclonal antibody treatments are then required in order to target the IgE or the IL-4 and IL-13 pathways. However, these are very costly and require patients to inject for years or even throughout their lives.

For several years now, Inserm research director Laurent Reber and his colleagues at the Infinity laboratory in Toulouse, along with Pierre Bruhns’ team at Institut Pasteur, have been working in collaboration with French company NEOVACS to develop a vaccine to open up new therapeutic avenues for patients with severe allergic asthma.

A Vaccine Effective Against Human Cytokines

In a previous study, the researchers had showed the efficacy in mice of a conjugate vaccine [2] called Kinoïde^® (see box). The results suggested that this vaccine induced the sustained production of antibodies directed specifically against murine IL-4 and IL-13, as well as a reduction in the symptoms of allergic asthma in those animals.

Following these encouraging early data and in order to envisage clinical trials in humans, it was necessary to develop a vaccine that is also capable of neutralizing human IL-4 and IL-13 cytokines. In order to test the efficacy of this new vaccine, the scientists this time used a model of house dust mite allergic asthma in “humanized” mice, whose genes encoding murine cytokines IL-4 and IL-13 were replaced with the respective human genes.

Again, the results are promising: vaccination induced a major antibody response, capable of neutralizing human IL-4 and IL-13 cytokines, with no reduction in the efficacy of the vaccine, up to three months after injection (time corresponding to the total duration of this study).

A significant effect on asthma symptoms was also observed: in the animals studied, vaccination was associated with reduced IgE and eosinophilia levels as well as reduced mucus production and airway hyperreactivity.

 “This study provides proof of concept of the vaccine’s efficacy in neutralizing human proteins that play a key role in allergic asthma, bringing us closer to its testing in humans. We are currently in discussion with the various project partners regarding the set-up of these clinical trials,” concludes Reber.

“Vaccination against allergic asthma represents the hope of a long-term treatment for this chronic disease and the prospect of reducing allergy symptoms related to other factors, since this vaccine targets molecules involved in different allergies,” points out Pierre Bruhns, head of the Antibodies in Therapy and Pathology unit at Institut Pasteur.

[1] Toulouse Institute for Infectious and Inflammatory Diseases (Inserm/CNRS/Université Toulouse III)

[2] A conjugate vaccine  is a vaccine containing an antigen associated with a protein to increase its efficacy

This study, sponsored and funded by ANRS | Emerging Infectious Diseases in partnership with Roche[1], was conducted by a research team from the Paris Public Hospitals Group AP-HP, Université Paris Cité, Inserm, and Sorbonne Université in collaboration with the associations AIDES and Coalition PLUS. It demonstrates the efficacy of both a meningococcal B vaccine in reducing the risk of gonorrhea infection and the use of the antibiotic doxycycline as a preventive treatment against sexually transmitted infections, when taken within 72h after sex. Following the first mpox cases in France, the study scope was expanded, adding the possibility to observe the efficacy of the Modified Vaccinia Ankara (MVA-BN) vaccine against the mpox virus responsible for the epidemic that emerged in 2022.

In recent years, France has seen an increase in sexually transmitted infections (STIs), including bacterial infections such as syphilis, chlamydia and gonorrhea, which particularly affect men who have sex with men (MSM). It was this population which has been mainly affected by the mpox epidemic, which emerged in France in May 2022.

The ANRS DOXYVAC trial was designed to evaluate interventions aimed at preventing these infections. It has been ongoing since January 2021 in MSM using PrEP to prevent HIV infection and highly exposed to the risk of STIs and having presented at least one STI during the year prior to their participation in it[2].

The ANRS DOXYVAC trial aims to measure the efficacy of an antibiotic and a vaccine in preventing bacterial STIs in MSM.

Enrollment was stopped early and the two interventions were proposed to all participants following the promising results with doxycycline in the U.S. study DOXYPEP and at the recommendation of the data and safety monitoring board following an interim analysis requested by them.

The study is evaluating the efficacy of post-exposure prophylaxis (PEP)[3] for bacterial STIs that combines the antibiotic doxycycline and vaccination with Bexsero® against meningococcus B[4]. Between January 2021 and July 2022, 502 MSM volunteers living in the Paris region were randomly assigned to into four groups: the first receiving doxycycline PEP to be taken within 72h after condomless sex; the second receiving vaccination with Bexsero®; the third a combination of these two interventions; and the fourth none of the two interventions.

The volunteers had a median age of 39 years, a median of 10 sexual partners in the last 3 months and received a median follow-up of 9 months. They were monitored and tested every 3 months for symptoms of gonorrhea, chlamydia and syphilis infections.

The researchers compared the incidence of a first episode of chlamydia or syphilis infection between the group that received doxycycline and the group that did not and found it to be 5.6 and 35.4 per 100 person-years[5], respectively (84% reduction in the risk of chlamydia or syphilis infection). As for the incidence of a first episode of gonorrhea infection in these same groups, this was found to be 20.5 and 41.3 per 100 person-years (51% reduction). After 3 months, the incidence of a first episode of gonorrhea infection in the Bexsero®-vaccinated group and the unvaccinated group was 9.8 and 19.7 per 100 person-years (51% reduction). No severe adverse effects relating to these two procedures were observed.

“The use of doxycycline for post-exposure prophylaxis has shown itself to be effective in reducing the incidence of both chlamydia and syphilis infection. This antibiotic has also had a significant impact, just like the meningococcal B vaccine, on the incidence of gonorrhea infections. This is the first time that a vaccine has shown an effect on a sexually transmitted bacterial infection,” concludes Prof. Jean-Michel Molina (Université Paris Cité and Department of Infectious Diseases at Hôpital Saint-Louis and Lariboisière, AP-HP, and Université Paris Cité), the study’s coordinating investigator.

Follow-up of the participants will continue until the end of 2023 to ensure that these prevention strategies, which have now been offered to all the participants, are effective in the medium term.

This study, which forms part of a global prevention effort, combines several risk reduction measures (repeated screening for HIV and STIs, vaccination against hepatitis A and B, distribution of condoms and gels). The participants also have the possibility to benefit from community support, therapeutic education, or both.

Beyond bacterial STIs, DOXYVAC has made it possible to analyze the impact of the MVA-BN vaccine on the incidence of the mpox virus rapidly after the appearance of the first cases.

In France, the first cases of infection with the mpox virus appeared in May 2022. For the first time, the risk of human-to-human transmission of this virus through sexual contact has been observed. It has therefore been recommended since July 11, 2022 that the vaccine be used as a protective measure for multi-partner MSM.

In view of this observation, the research teams considered it necessary to include in DOXYVAC a component dedicated to studying the vaccine impact on the incidence of mpox virus in MSM taking PrEP, given that these volunteers are at risk of developing mpox. Among the 502 participants in DOXYVAC, the researchers analyzed, in this specific component, the information regarding 472 people whose data were available before and after May 8, 2022. These participants had reported having a median of 10 partners in the previous 3 months, and 20% had received a smallpox vaccine in childhood.

The researchers compared the pre-epidemic (i.e. until May 8, 2022) characteristics of the 77 volunteers having contracted mpox to the “control” volunteers who had not had the virus. They found that the cases of mpox affected younger people (37 vs. 40 years) who had had more sexual partners in the previous 3 months (7 vs. 5), and among whom fewer had been vaccinated against smallpox in childhood (4% vs. 23%). In people who did not have mpox infection, the proportion having had more than 10 partners over a 3-month period had decreased between the pre-epidemic and epidemic periods (up to and after May 8, 2022).

The incidence of mpox virus infection was 67.4 per 1 000 person-months between May 9 and July 10. It fell to 24.4 per 1 000 person-months between July 11 (date from which it was possible to get vaccinated) and September 20. The research team found that simply being vaccinated against the mpox virus in 2022 was associated with a reduced risk of developing the disease with an efficacy of 99%; the impact of behavioral change was limited in this highly vaccinated population (87%).

“This vaccine provides a high level of protection against the mpox virus,” explains Prof. Jade Ghosn (Université Paris Cité, Department of Infectious and Tropical Diseases of Bichat-Claude-Bernard Hospital AP-HP), DOXYVAC co-investigator and the researcher behind the implementation of the study’s “mpox” component.

AIDES, which has developed numerous risk reduction tools during the mpox crisis and participated in providing community support in these studies, welcomes these results.

For Camille Spire, president of the association, “the emergence of new effective tools to add to the existing prevention arsenal is to be welcomed, especially since during the mpox crisis we have noted a high level of vaccine uptake by the people exposed to the virus. We will work to ensure that the effective accessibility of these tools is supported by public policies in terms of the fight against STIs”.

Vincent Leclercq, managing director of Coalition PLUS adds: “in order to achieve their full potential, these prevention tools must reach all the populations at which they are targeted. However, access to vaccines and medicines is too often restricted to the richest countries. We have seen it with the mpox epidemic: only the countries of the North have been able to set up vaccination campaigns”.

[1] Roche Molecular System and Roche Diagnostics France provided – free of charge – the kits, consumables and reagents needed to detect Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium.

[2] These men are participants in the HIV infection prevention cohort ANRS PREVENIR.

[3] Post-exposure prophylaxis (PEP) is the use of preventive treatment in people who have recently been exposed to a risk of disease transmission to prevent them from developing it.

[4] Meningococcus B (Neisseria meningitidis) is a bacterium that can cause meningitis. It is close to gonococcus (Neisseria gonorrhoeae).

[5] X per 100 person-years: this means that out of 100 patients followed up for one year, there is a probability of observing X events (in this case an STI).

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Scientists from the Institut Pasteur, Necker-Enfants Malades Hospital (AP-HP), Inserm in the Imagine Institute, Université Paris Cité and the Alfort National Veterinary School (EnvA) have identified a previously unknown species of circovirus, provisionally named human circovirus 1 (HCirV-1). Circoviruses are a family of small, highly resistant DNA viruses that were initially identified in 1974 in various animal species, where they can cause respiratory, renal, dermatological and reproductive problems. HCirV-1 is a novel virus that is distant from known animal circoviruses. It was shown to be implicated in damage to the liver of a patient undergoing immunosuppressive treatment. This discovery of the first circovirus in humans, linked to hepatitis, was published in the journal Emerging Infectious Diseases on January 3, 2023.

Although the transmission of animal viruses to humans is regularly reported in the scientific literature, it is rare for a novel virus to be identified in a patient in Europe. But as part of a recent study, scientists and physicians have identified the first circovirus involved in human hepatitis.

“The patient had unexplained chronic hepatitis, with few symptoms. She had received a heart-lung transplant 17 years earlier and had been monitored regularly since. We had access to a large number of samples over several years and were therefore able to identify this novel virus, which was completely unexpected,” explains Marc Eloit, last author of the study, Head of the Institut Pasteur’s Pathogen Discovery laboratory and a Professor of Virology at the Alfort National Veterinary School (EnvA). His laboratory specializes in the identification of pathogens in patients suspected of severe infection of unknown cause.

In March 2022, in collaboration with the Department of Clinical Microbiology at Necker-Enfants Malades Hospital (AP-HP), the pathological tissue samples of this 61-year-old female patient receiving immunosuppressive treatment, whose hepatitis had no identifiable cause, were sequenced to search for microbial sequences. The RNA (ribonucleic acid) sequences extracted from the tissues were analyzed and compared with those of known microbes.

“The aim is to identify sequences of interest among all the sequences obtained, which is like searching for a needle in a haystack!” continues the scientist Marc Eloit.

These thousands of RNA sequences were analyzed in parallel using mNGS (metagenomic next-generation sequencing) high-throughput sequencing techniques and sophisticated algorithms. After ruling out common etiologies, the analysis led to the identification of a previously unknown species of circovirus, provisionally named human circovirus 1 (HCirV-1). No other viral or bacterial sequence was found.

The involvement of HCirV-1 in the hepatitis was then demonstrated by analyzing samples taken from the patient in previous years as part of her post-transplant treatment. The results showed that the HCirV-1 viral genome was undetectable in the blood samples from 2017 to 2019, then that its concentration peaked in September 2021. Viral replication in liver cells was demonstrated (2 to 3% of liver cells were infected), pointing to the role of HCirV-1 in liver damage: once the virus has used the resources in the liver cell to replicate, it destroys the cell.

From November 2021 onwards, following antiviral treatment, the patient’s liver enzymes returned to normal levels, indicating the end of hepatic cytolysis.

Diagnosing hepatitis of unknown etiology remains a major challenge, as shown by the cases of acute hepatitis reported in children in the United Kingdom and Ireland last April and signaled by WHO.

“We need to know the cause of the hepatitis, and especially whether or not it is viral, to be able to offer suitable treatment and monitor patients effectively. The identification of this novel virus that is pathogenic in humans, and the development of a test that can be performed by any hospital laboratory, offers a new tool for diagnosing and monitoring patients with hepatitis,” stresses Anne Jamet from the Department of Clinical Microbiology at Necker-Enfants Malades Hospital (AP-HP), who is also affiliated with Inserm and co-last author of the study.

Although some circoviruses are pathogenic for animals and vaccines can be administered, especially in pigs, this is the first known circovirus to be pathogenic for humans. The patient’s symptoms remained mild; the virus was able to be identified because she was being closely monitored following her combined transplant. The origin of the virus – whether it is circulating in humans or of animal origin – has yet to be identified, and the source of infection (contact, food, etc.) remains unknown. Following their discovery, the scientists developed a specific PCR test that is now available for etiological diagnosis of hepatitis of unknown origin. A serological test is also being developed.

“These results show the value of this type of sequencing analysis in identifying novel or unexpected pathogens. It is always important for clinicians to know whether or not an infection is viral so that they can adapt the treatment accordingly. It is also crucial to be able to identify a novel pathogen when an infection remains unexplained and to develop a diagnostic test, because any new case of human infection with an emerging pathogen may potentially signal the start of an outbreak,” concludes Marc Eloit. The test is available for the medical community and can now be easily performed for other cases of unexplained hepatitis.