A recombinant chimeric influenza virus vaccine expressing the consensus H3 hemagglutinin elicits broad hemagglutination inhibition antibodies against divergent swine H3N2 influenza viruses

Evolutionary analysis of Hemagglutinin and neuraminidase gene variation in H1N1 swine influenza virus from vaccine intervention in China

Influenza poses a significant threat to the global economy and health. Inactivated virus vaccines were introduced in China for prevention in 2018. In this study, three pairs of hemagglutinin (HA) and neuraminidase (NA) gene sequences were obtained from three Swine influenza virus (IAV-S) inactivated vaccine strains that were marketed in China in 2018. Phylogenetic analysis was carried out with HA and NA gene sequences to investigate the relationship between vaccine use and virus genetic drift. The findings showed that the evolutionary rate of HA remained relatively stable from 2012 to 2017, with an average genetic distance of approximately 0.020731195. However, following the introduction of the swine influenza vaccine, there was a notable acceleration in the evolutionary rate of HA, accompanied by a significant increase in the genetic distance. In 2018, the value was 0.111750269, while in 2019 it was 0.176389393. In contrast, the evolution of NA was relatively smooth, with an average genetic distance of approximately 0.030386708. Finally, we demonstrated that commercial vaccines are weak neutralizers of wild strains through immunization experiments in animals. Thus, we have reason to believe that mutations in the virus favor virus evasion of vaccine immunity. Our findings suggest that vaccine use may significantly impact the evolution of the influenza virus by potentially stimulating mutations. The selection pressure of vaccine antibodies played a role in regulating the variation of IAV-S-H1N1.

Emerging Threats of Highly Pathogenic Avian Influenza A (H5N1) in US Dairy Cattle: Understanding Cross-Species Transmission Dynamics in Mammalian Hosts

The rapid geographic spread of the highly pathogenic avian influenza (HPAI) A(H5N1) virus in poultry, wild birds, and other mammalian hosts, including humans, raises significant health concerns globally. The recent emergence of HPAI A(H5N1) in agricultural animals such as cattle and goats indicates the ability of the virus to breach unconventional host interfaces, further expanding the host range. Among the four influenza types-A, B, C, and D, cattle are most susceptible to influenza D infection and serve as a reservoir for this seven-segmented influenza virus. It is generally thought that bovines are not hosts for other types of influenza viruses, including type A. However, this long-standing viewpoint has been challenged by the recent outbreaks of HPAI A(H5N1) in dairy cows in the United States. To date, HPAI A(H5N1) has spread into fourteen states, affecting 299 dairy herds and causing clinical symptoms such as reduced appetite, fever, and a sudden drop in milk production. Infected cows can also transmit the disease through raw milk. This review article describes the current epidemiological landscape of HPAI A(H5N1) in US dairy cows and its interspecies transmission events in other mammalian hosts reported across the globe. The review also discusses the viral determinants of tropism, host range, adaptative mutations of HPAI A(H5N1) in various mammalian hosts with natural and experimental infections, and vaccination strategies. Finally, it summarizes some immediate questions that need to be addressed for a better understanding of the infection biology, transmission, and immune response of HPAI A(H5N1) in bovines.

Research progress in Fc-effector functions against SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused more than 676 million cases in the global human population with approximately 7 million deaths and vaccination has been proved as the most effective countermeasure in reducing clinical complications and mortality rate of SARS-CoV-2 infection in people. However, the protective elements and correlation of protection induced by vaccination are still not completely understood. Various antibodies with multiple protective mechanisms can be induced simultaneously by vaccination in vivo, thereby complicating the identification and characterization of individual correlate of protection. Recently, an increasing body of observations suggests that antibody-induced Fc-effector functions play a crucial role in combating SARS-CoV-2 infections, including neutralizing antibodies-escaping variants. Here, we review the recent progress in understanding the impact of Fc-effector functions in broadly disarming SARS-CoV-2 infectivity and discuss various efforts in harnessing this conserved antibody function to develop an effective SARS-CoV-2 vaccine that can protect humans against infections by SARS-CoV-2 virus and its variants of concern.

Nucleoprotein reassortment enhanced transmissibility of H3 1990.4.a clade influenza A virus in swine

The increased detection of H3 C-IVA (1990.4.a) clade influenza A viruses (IAVs) in US swine in 2019 was associated with a reassortment event to acquire an H1N1pdm09 lineage nucleoprotein (pdmNP) gene, replacing a TRIG lineage NP (trigNP). We hypothesized that acquiring the pdmNP conferred a selective advantage over prior circulating H3 viruses with a trigNP. To investigate the role of NP reassortment in transmission, we identified two contemporary 1990.4.a representative strains (NC/19 and MN/18) with different evolutionary origins of the NP gene. A reverse genetics system was used to generate wild-type (wt) strains and swap the pdm and TRIG lineage NP genes, generating four viruses: wtNC/19-pdmNP, NC/19-trigNP, wtMN/18-trigNP, and MN/18-pdmNP. The pathogenicity and transmission of the four viruses were compared in pigs. All four viruses infected 10 primary pigs and transmitted to five indirect contact pigs per group. Pigs infected via contact with MN/18-pdmNP shed virus 2 days earlier than pigs infected with wtMN/18-trigNP. The inverse did not occur for wtNC/19-pdmNP and NC/19-trigNP. This suggests that pdmNP reassortment resulted in a combination of genes that improved transmission efficiency when paired with the 1990.4.a hemagglutinin (HA). This is likely a multigenic trait, as replacing the trigNP gene did not diminish the transmission of a wild-type IAV in swine. This study demonstrates how reassortment and evolutionary change of internal genes can result in more transmissible viruses that influence HA clade detection frequency. Thus, rapidly identifying novel reassortants paired with dominant hemagglutinin/neuraminidase may improve the prediction of strains to include in vaccines.IMPORTANCEInfluenza A viruses (IAVs) are composed of eight non-continuous gene segments that can reassort during coinfection of a host, creating new combinations. Some gene combinations may convey a selective advantage and be paired together preferentially. A reassortment event was detected in swine in the United States that involved the exchange of two lineages of nucleoprotein (NP) genes (trigNP to pdmNP) that became a predominant genotype detected in surveillance. Using a transmission study, we demonstrated that exchanging the trigNP for a pdmNP caused the virus to shed from the nose at higher levels and transmit to other pigs more rapidly. Replacing a pdmNP with a trigNP did not hinder transmission, suggesting that transmission efficiency depends on interactions between multiple genes. This demonstrates how reassortment alters IAV transmission and that reassortment events can provide an explanation for why genetically related viruses with different internal gene combinations experience rapid fluxes in detection frequency.

Inactivated recombinant influenza vaccine: the promising direction for the next generation of influenza vaccine

INTRODUCTION

Vaccination is the most effective method to control the prevalence of seasonal influenza and the most widely used influenza vaccine is the inactivated influenza vaccine (IIV). Each season, the influenza vaccine must be updated to be most effective against current circulating variants. Therefore, developing a universal influenza vaccine (UIV) that can elicit both broad and durable protection is of the utmost importance.

AREA COVERED

This review summarizes and compares the available influenza vaccines in the market and inactivation methods used for manufacturing IIVs. Then, we discuss the latest progress of the UIV development in the IIV format and the challenges to address for moving these vaccine candidates to clinical trials and commercialization. The literature search was based on the Centers for Disease Control and Prevention (CDC) and the PubMed databases.

EXPERT OPINION

The unmet need for UIV is the primary aim of developing the next generation of influenza vaccines. The IIV has high antigenicity and a refined manufacturing process compared to most other formats. Developing the UIV in IIV format is a promising direction with advanced biomolecular technologies and next-generation adjuvant. It also inspires the development of universal vaccines for other infectious diseases.