Influenza season in Réunion dominated by influenza B virus circulation associated with numerous cases of severe disease, France, 2014

Multivalent Epigraph Hemagglutinin Vaccine Protects against Influenza B Virus in Mice

Influenza B virus is a respiratory pathogen that contributes to seasonal epidemics, accounts for approximately 25% of global influenza infections, and can induce severe disease in young children. While vaccination is the most commonly used method of preventing influenza infections, current vaccines only induce strain-specific responses and have suboptimal efficacy when mismatched from circulating strains. Further, two influenza B virus lineages have been described, B/Yamagata-like and B/Victoria-like, and the limited cross-reactivity between the two lineages provides an additional barrier in developing a universal influenza B virus vaccine. Here, we report a novel multivalent vaccine using computationally designed Epigraph hemagglutinin proteins targeting both the B/Yamagata-like and B/Victoria-like lineages. When compared to the quadrivalent commercial vaccine, the Epigraph vaccine demonstrated increased breadth of neutralizing antibody and T cell responses. After lethal heterologous influenza B virus challenge, mice immunized with the Epigraph vaccine were completely protected against both weight loss and mortality. The superior cross-reactive immunity conferred by the Epigraph vaccine immunogens supports their continued investigation as a universal influenza B virus vaccine.

Influenza B: Prospects for the Development of Cross-Protective Vaccines

In this review, we analyze the epidemiological and ecological features of influenza B, one of the most common and severe respiratory infections. The review presents various strategies for cross-protective influenza B vaccine development, including recombinant viruses, virus-like particles, and recombinant proteins. We provide an overview of viral proteins as cross-protective vaccine targets, along with other updated broadly protective vaccine strategies. The importance of developing such vaccines lies not only in influenza B prevention, but also in the very attractive prospect of eradicating the influenza B virus in the human population.

Comparative efficacy assessment of antiviral alone and antiviral-antibiotic combination in prevention of influenza-B infection associated complications

OBJECTIVE

The study aimed to compare the efficacy of antiviral drug alone and antiviral-antibiotic combination therapy in prevention of complications associated with influenza B hospitalized patients.

METHOD

Laboratory confirmed influenza B hospitalized patients presented in emergency room after 48 hours of symptoms onset were identified and divided into two groups; Group-1 patients were initiated on Antiviral drug (oseltamivir) alone while Group-2 patients were initiated on Antiviral drug (oseltamivir) in combination with Antibiotic for at least 3 days. Patients were evaluated for different clinical outcomes among both treatment group.

RESULTS

A total of 153 and 131 patients were identified for Group-1 and Group-2, respectively. Clinical outcomes such as secondary bacterial infections (20.9%-vs-9.1%; P = 0.031), need of respiratory support (28.7%-vs-12.9%; P = 0.002), length of hospitalization stay (6.57-vs-4.95 days; P = <0.001), incidences of ICU admission (15.7%-vs-7.6%; P = 0.036), early clinical failure (32.6%-vs-16.1%; P = 0.01), and time to clinical stability (4.83-vs-4.1 days; P = 0.001) were found to be statistically less significant (P-value <0.05) for Group-2 patients.

CONCLUSION

Early initiation of antibiotic therapy in combination with oseltamivir was found to be more efficacious than oseltamivir alone in prevention of influenza B-associated complications especially in high-risk influenza patients.

Influenza Sentinel Surveillance and Severe Acute Respiratory Infection in a Reference Hospital in Southern Brazil

INTRODUCTION

We report the results of the active surveillance of influenza infections in hospitalized patients and the evaluation of the seasonality and correlation with temperature and rainfall data.

METHODS

During the 2-year study period, 775 patients were tested for 15 respiratory viruses (RVs).

RESULTS

Most of the 57% of (n=444) virus-positive samples were human rhinovirus and respiratory syncytial virus. However, 10.4% (n=46) were influenza virus (80% FluA; 20% FluB). Age and SARI were significantly associated with influenza. FluB circulation was higher is 2013.

CONCLUSIONS

In the post-epidemic period, influenza remains an important cause of hospitalization in SARI patients.

Development of Influenza B Universal Vaccine Candidates Using the "Mosaic" Hemagglutinin Approach

Influenza B viruses cause seasonal epidemics and are a considerable burden to public health. However, protection by current seasonal vaccines is suboptimal due to the antigenic changes of the circulating strains. In this study, we report a novel universal influenza B virus vaccination strategy based on "mosaic" hemagglutinins. We generated mosaic B hemagglutinins by replacing the major antigenic sites of the type B hemagglutinin with corresponding sequences from exotic influenza A hemagglutinins and expressed them as soluble trimeric proteins. Sequential vaccination with recombinant mosaic B hemagglutinin proteins conferred cross-protection against both homologous and heterologous influenza B virus strains in the mouse model. Of note, we rescued recombinant influenza B viruses expressing mosaic B hemagglutinins, which could serve as the basis for a universal influenza B virus vaccine.IMPORTANCE This work reports a universal influenza B virus vaccination strategy based on focusing antibody responses to conserved head and stalk epitopes of the hemagglutinin. Recombinant mosaic influenza B hemagglutinin proteins and recombinant viruses have been generated as novel vaccine candidates. This vaccine strategy provided broad cross-protection in the mouse model. Our findings will inform and drive development toward a more effective influenza B virus vaccine.

Influenza virus N-linked glycosylation and innate immunity

Influenza viruses cause seasonal epidemics and sporadic pandemics in humans. The virus’s ability to change its antigenic nature through mutation and recombination, and the difficulty in developing highly effective universal vaccines against it, make it a serious global public health challenge. Influenza virus’s surface glycoproteins, hemagglutinin and neuraminidase, are all modified by the host cell’s N-linked glycosylation pathways. Host innate immune responses are the first line of defense against infection, and glycosylation of these major antigens plays an important role in the generation of host innate responses toward the virus. Here, we review the principal findings in the analytical techniques used to study influenza N-linked glycosylation, the evolutionary dynamics of N-linked glycosylation in seasonal versus pandemic and zoonotic strains, its role in host innate immune responses, and the prospects for lectin-based therapies. As the efficiency of innate immune responses is a critical determinant of disease severity and adaptive immunity, the study of influenza glycobiology is of clinical as well as research interest.

[Quadrivalent influenza vaccine: What is changed and what are the benefits?]

Currently, circulating viruses responsible for annual seasonal influenza epidemics belong to two influenza A subtypes, A(H1N1) and A(H3N2), and to two antigenically distinct type B lineages, B/Yamagata and B/Victoria lineages. Like diseases due to influenza A virus, influenza B virus diseases may have severe consequences and should be prevented. Until now, in France, the vaccines used to prevent seasonal influenza were trivalent, systematically targeting viruses belonging to both A subtypes and to one or other of the B lineages. The protective efficacy of trivalent vaccines is diminished during the seasons when viruses belonging to both B lineages cocirculated or when the circulating dominant type B virus belonged to a lineage different from that targeted by the vaccine strain. By targeting viruses belonging to both B lineages, quadrivalent vaccines improve the antigenic concordance between circulating and vaccine type B strains. Three inactivated quadrivalent vaccines are authorized for marketing in France and should be available for the 2018-2019 season. It is expected that, by providing enlarged protection, these quadrivalent influenza vaccines will improve vaccine efficacy, the confidence in immunization of the public, the satisfaction of health professionals, and ultimately will help to complete immunization coverage.

Identification of immunodominant CD8 epitope in the stalk domain of influenza B viral hemagglutinin

Human infections by type B influenza virus constitute about 25% of all influenza cases. The viral hemagglutinin is comprised of two subunits, HA1 and HA2. While HA1 is constantly evolving in an unpredictable fashion, the HA2 subunit is highly conserved, making it a potential candidate for a universal vaccine. However, immunodominant epitopes in the HA2 subunit remain largely unknown. To delineate MHC Class I epitopes, we first identified 9-mer H-2K^d-restricted CD8 T cell epitopes in the HA2 domain by in silico analyses, followed by evaluating the immunodominance of these peptides in mice challenged with the virus. Of three peptides selected through in silico analysis, the universally conserved peptide, YYSTAASSL (B/HA2-190), possessed the highest predicted binding affinity to MHC Class I and was most effective in inducing IL-2 and TNF-α in mouse splenocytes. Importantly, the peptide demonstrated best capability of stimulating peptide-specific ex-vivo cytotoxicity against target cells. Taken together, this finding would be of value for assessment of cell-mediated immune responses elicited by vaccines based on the highly conserved HA2 stalk domain.

Universal influenza virus vaccines and therapeutics: where do we stand with influenza B virus?

The development of a broadly protective or universal influenza virus vaccine is currently a public health priority worldwide. The vast majority of these efforts is exclusively focused on influenza A viruses. While influenza A viruses cause the majority of all influenza cases worldwide, influenza B viruses should not be ignored. Approximately 25% of all influenza cases are caused by influenza B viruses which circulate as two distinct B/Victoria/2/87-like and B/Yamagata/16/88-like lineages. In contrast to popular belief, influenza B cases frequently cause significant morbidity and mortality, especially in children. Similar to influenza A viruses, influenza B viruses drift antigenically and the influenza B components of current vaccines have to be reformulated almost on an annual basis. A broadly protective vaccine against influenza B viruses is therefore urgently needed. Here we review both broadly protective anti-influenza B antibodies as well as the sparse attempts to create a universal influenza B virus vaccine.

The burden of mood-disorder/cerebrovascular disease comorbidity: essential neurobiology, psychopharmacology, and physical activity interventions

Cardio-vascular diseases (CVDs) and CVD-related disorders (including cerebrovascular diseases; CBVDs) are a major public health concern as they represent the leading cause of mortality and morbidity in developed countries. Patients with CVDs and CBVDs co-morbid with mood disorders, especially bipolar disorder (BD) and major depressive disorder (MDD), suffer reduced quality-of-life and significant disability adjusted for years of life and mortality. The relationship between CVDs/CBVDs and mood disorders is likely to be bidirectional. Evidence for shared genetic risk of pathways involved in stress reaction, serotonin or dopamine signalling, circadian rhythms, and energy balance was reported in genome-wide association studies. There is some evidence of a neuroprotective effect of various antidepressants, which may be boosted by physical exercise, especially by aerobic ones. Patients with CVDs/CBVDs should be routinely attentively evaluated for the presence of mood disorders, with tools aimed at detecting both symptoms of depression and of hypomania/mania. Behavioural lifestyle interventions targeting nutrition and exercise, coping strategies, and attitudes towards health should be routinely provided to patients with mood disorders, to prevent the risk of CVDs/CBVDs. A narrative review of the evidence is herein provided, focusing on pharmacological and physical therapy interventions.

Broadly protective murine monoclonal antibodies against influenza B virus target highly conserved neuraminidase epitopes

A substantial proportion of influenza-related childhood deaths are due to infection with influenza B viruses, which co-circulate in the human population as two antigenically distinct lineages defined by the immunodominant receptor binding protein, hemagglutinin. While broadly cross-reactive, protective monoclonal antibodies against the hemagglutinin of influenza B viruses have been described, none targeting the neuraminidase, the second most abundant viral glycoprotein, have been reported. Here, we analyze a panel of five murine anti-neuraminidase monoclonal antibodies which demonstrate broad binding, neuraminidase inhibition, in vitro antibody-dependent cell-mediated cytotoxicity, and in vivo protection against influenza B viruses belonging to both HA lineages and spanning over 70 years of antigenic drift. Electron microscopic analysis of two neuraminidase-antibody complexes shows that the conserved neuraminidase epitopes are located on the head of the molecule and that they are distinct from the enzymatic active site. In the mouse model, one therapeutic dose of antibody 1F2 was more protective than the current standard of treatment, oseltamivir, given twice daily for six days.

A major outbreak of conjunctivitis caused by coxsackievirus A24, Réunion, January to April 2015

From January to April 2015, Réunion experienced a major outbreak of acute haemorrhagic conjunctivitis (AHC) caused by coxsackievirus A24, which heavily impacted the healthcare system. According to the general practitioners' (GP) sentinel network, the number of medical consultations due to conjunctivitis during this period was estimated at ca 100,000. This report describes the characteristics of the outbreak, which were obtained through several different yet complementary surveillance systems on the island. These included the network of hospital emergency departments (OSCOUR network), the GPs' sentinel network, an Internet-based population cohort ('Koman i lé') participating in a survey on distinct symptoms including 'red eyes' and the monitoring of eye drop sales. Overall the results of the different surveillance approaches were in good agreement regarding the outbreak dynamic. A peak of patients with conjunctivitis was detected in the first 15 days of March (week 10 and 11), coinciding with increased eye drop sales on the island. Strains recovered from outbreak cases belonged to genotype IV and were most closely related to strains identified in AHC outbreaks in China, Egypt and Japan since 2010. Continued surveillance of AHC in Réunion remains important not only locally, but also because frequent exchanges between the island and mainland France may lead to introduction of this virus in Europe.

Chimeric Hemagglutinin Constructs Induce Broad Protection against Influenza B Virus Challenge in the Mouse Model

Seasonal influenza virus epidemics represent a significant public health burden. Approximately 25% of all influenza virus infections are caused by type B viruses, and these infections can be severe, especially in children. Current influenza virus vaccines are an effective prophylaxis against infection but are impacted by rapid antigenic drift, which can lead to mismatches between vaccine strains and circulating strains. Here, we describe a broadly protective vaccine candidate based on chimeric hemagglutinins, consisting of globular head domains from exotic influenza A viruses and stalk domains from influenza B viruses. Sequential vaccination with these constructs in mice leads to the induction of broadly reactive antibodies that bind to the conserved stalk domain of influenza B virus hemagglutinin. Vaccinated mice are protected from lethal challenge with diverse influenza B viruses. Results from serum transfer experiments and antibody-dependent cell-mediated cytotoxicity (ADCC) assays indicate that this protection is antibody mediated and based on Fc effector functions. The present data suggest that chimeric hemagglutinin-based vaccination is a viable strategy to broadly protect against influenza B virus infection.IMPORTANCE While current influenza virus vaccines are effective, they are affected by mismatches between vaccine strains and circulating strains. Furthermore, the antiviral drug oseltamivir is less effective for treating influenza B virus infections than for treating influenza A virus infections. A vaccine that induces broad and long-lasting protection against influenza B viruses is therefore urgently needed.

A major impact of the influenza seasonal epidemic on intensive care units, Réunion, April to August 2016

The 2016 seasonal influenza in Réunion in the southern hemisphere, was dominated by influenza A(H1N1)pdm09 (possibly genogroup 6B.1). An estimated 100,500 patients with acute respiratory infection (ARI) consulted a physician (cumulative attack rate 11.9%). Sixty-six laboratory-confirmed cases (65.7/100,000 ARI consultations) were hospitalised in an intensive care unit, the highest number since 2009. Impact on intensive care units was major. Correlation between severe cases was 0.83 between Réunion and France and good for 2009 to 2015.

Epidemiology of influenza B in Australia: 2001-2014 influenza seasons

Background

Influenza B is characterised by two antigenic lineages: B/Victoria and B/Yamagata. These lineages circulate together with influenza A during influenza seasons, with varying incidence from year to year and by geographic region.

Objective

To determine the epidemiology of influenza B relative to influenza A in Australia.

Methods

Laboratory‐confirmed influenza notifications between 2001 and 2014 in Australia were obtained from the Australian National Notifiable Diseases Surveillance System.

Results

A total of 278 485 laboratory‐confirmed influenza cases were notified during the study period, comprising influenza A (82.2%), B (17.1%) and ‘other and untyped’ (0.7%). The proportion of notifications that were influenza B was highest in five‐ to nine‐year‐olds (27.5%) and lowest in persons aged 85 years and over (11.5%). Of all B notifications with lineage determined, 77.1% were B/Victoria and 22.9% were B/Yamagata infections. Mismatches between the dominant B lineage in a season and the trivalent vaccine B lineage occurred in over one‐third of seasons during the study years. In general, influenza B notifications peaked later than influenza A notifications.

Conclusion

The proportion of circulating influenza B in Australia during 2001‐2014 was slightly lower than the global average and was dominated by B/Victoria. Compared with influenza A, influenza B infection was more common among older children and young adults and less common in the very elderly. Influenza B lineage mismatch with the trivalent vaccine occurred about one‐third of the time.

Etiology of Influenza-Like Illnesses from Sentinel Network Practitioners in Réunion Island, 2011-2012

In Réunion Island, despite an influenza surveillance established since 1996 by the sentinel general practitioner’s network, little is known about the etiology of Influenza like-illness (ILI) that differs from influenza viruses in a tropical area. We set up a retrospective study using nasal swabs collected by sentinel GPs from ILI patients in 2011 and 2012. A total of 250 swabs were randomly selected and analyzed by multiplex reverse transcriptase polymerase chain reaction (RT-PCR) including research of 18 viruses and 4 bacteria. We detected respiratory viruses in 169/222 (76.1%) samples, mostly rhinovirus (23.4%), influenza A virus (21.2%), influenza B virus (12.6%), coronavirus (4.9%) and Human metapneumovirus (3.6%). Nine swabs (5.3% of positive swabs) revealed co-infections with two viruses identified, among which six concerned co-infections with influenza viruses. We observed important seasonal differences, with circulation of Human Metapneumoviruses, RSV A and B and coronavirus only during summer; whereas parainfluenza viruses were identified only during winter. In conclusion, this study highlights a substantial circulation of multiple respiratory pathogens in Réunion Island throughout the year. It shows that ILI are not only attributable to influenza and underlines the need for biological surveillance. As the use of multiplex RT-PCR showed its efficacy, it is now used routinely in the surveillance of ILI.

Epidemiological and Phylogenetic Characteristics of Influenza B Infection in Severe Acute Respiratory Infection Cases in Beijing, 2014 to 2015

Influenza B viral infection is of great importance, but the epidemiological and phylogenetic characteristics of influenza B infection in severe acute respiratory infection (SARI) cases are still unclear.The clinical information of 2816 SARI cases and 467,737 influenza-like illness (ILI) cases in Beijing area from September 2014 to April 2015 were collected and analyzed. Among them, 91 influenza B viruses isolated from SARI cases were sequenced.The overall yield rate of influenza A/B infection was 14.21% and 27.77% in sampled SARI and ILI cases, respectively. Compared with influenza A infection, the frequency of influenza B infection in SARI cases was higher in younger patients. Phylogenetic analysis suggested that most tested hemagglutination genes belonged to Yamagata lineage Clade 3, which were similar with current circulating viruses but different with 2014 to 2015 influenza season vaccine strain (Clade 2). Importantly, HA-Y3/NA-V4 intralineage reassorting was identified in Beijing area for the first time, which can act as a possible risk factor of SARIs.The influenza activity and virus types/subtypes/lineages among SARI patients were well correlated with that of ILI cases. Furthermore, the potential risk of reassorted influenza B virus infection should not be overlooked.