THE SUSCEPTIBILITY OF SWINE TO THE VIRUS OF HUMAN INFLUENZA

High-throughput sequencing approaches applied to SARS-CoV-2

High-throughput sequencing is crucial for surveillance and control of viral outbreaks. During the ongoing coronavirus disease 2019 (COVID-19) pandemic, advances in the high-throughput sequencing technology resources have enhanced diagnosis, surveillance, and vaccine discovery. From the onset of the pandemic in December 2019, several genome-sequencing approaches have been developed and supported across the major sequencing platforms such as Illumina, Oxford Nanopore, PacBio, MGI DNBSEQTM and Ion Torrent. Here, we share insights from the sequencing approaches developed for sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between December 2019 and October 2022.

Preparedness of Military Public Health for Epidemic and Pandemic Recognition and Response

Disease epidemics have threatened American military preparedness and operational capabilities since 1775. The ongoing Severe Acute Respiratory Syndrome Coronavirus 2 (COVID-19) pandemic, which began in 2019, again demonstrates the significant potential for infectious diseases to impact military units and threaten military readiness. We reviewed the historical and continuing threats to the U.S. Military from infectious disease outbreaks, as well as changes in U.S. Military capabilities for conducting meaningful surveillance and response. We concluded that a structured review of military public health and preventive medicine capabilities should be conducted to assess the response to the COVID-19 pandemic and determine the capabilities necessary for infectious disease surveillance and response to future threats.

Novel reassortant swine H3N2 influenza A viruses in Germany

Analysis of 228 H3N2 swine influenza A virus isolates collected between 2003 and 2015 in Germany revealed important changes in molecular epidemiology. The data indicate that a novel reassortant, Rietberg/2014-like swine H3N2, emerged in February 2014 in Northern Germany. It is comprised of a hemagglutinin gene of seasonal H3N2 (A/Denmark/129/2005-like), a neuraminidase gene of Emmelsbuell/2009-like swine H1N2 and the internal gene cassette of pandemic H1N1 viruses. Together with Danish swine H3N2 strains of 2013-2015 with identical genome layout, the Rietberg/2014-like viruses represent a second swine H3N2 lineage which cocirculates with a variant of the Gent/1984-like swine H3N2 lineage. This variant, named Gent1984/Diepholz-like swine H3N2, has a Gent/1984-like HA and a Diepholz/2008-like NA; the origin of the internal gene cassette likely derived from avian-like swine H1N1. The first isolate of the Gent1984/Diepholz reassortant emerged in Northern Germany in September 2011 whereas the last German Gent/1984-like isolate was collected in October 2011.

Discussions on Swine Influenza in the British Isles

An outbreak of pneumonia affecting pigs (10–14 weeks old) was investigated; the mortality rate was low and recovery was slow. Hæmophilus influenzæ was recovered from half the pigs examined and the presence of a virus was demonstrated by the intranasal instillation of a filtrate of pneumonic lung. The virus was subsequently established in ferrets and neutralizing antibodies were demonstrated in the blood of convalescent pigs to the ferret-adapted virus.

Four further outbreaks of pneumonia in pigs revealed the presence of a virus and in two of these the agent was adapted to the ferret. Hæmophilus influenzæ was obtained from only a few of the pigs.

The lungs of pigs at a public slaughterhouse were examined for pneumonia and lesions were found in some cases. Hæmophilus influenzæ was recovered from three of forty affected lungs and transmission experiments with material from two lungs were made. The disease was reproduced in pigs and one of the strains was later adapted to the ferret.

Circulation of classical swine influenza virus in Europe between the wars?

The complete genomes of two swine influenza viruses from England were sequenced. Phylogenetic analysis revealed classical swine H1N1 viruses, one of which, A/swine/London, is closely related to virus strains of the early 1930s. Both strains are also antigenically related to A/swine/Iowa/15/1930, the strain originally isolated by Richard Shope. The source of A/swine/London is unknown, but its relationship to early classical swine influenza viruses suggests that the emergence of these viruses in Europe has to be antedated by 15-20 years.

Genetics, evolution, and the zoonotic capacity of European Swine influenza viruses

The European swine influenza virus lineage differs genetically from the classical swine influenza viruses and the triple reassortants found in North America and Asia. The avian-like swine H1N1 viruses emerged in 1979 after an avian-to-swine transmission and spread to all major European pig-producing countries. Reassortment of these viruses with seasonal H3N2 viruses led to human-like swine H3N2 viruses which appeared in 1984. Finally, human-like swine H1N2 viruses emerged in 1994. These are triple reassortants comprising genes of avian-like H1N1, seasonal H1N1, and seasonal H3N2 viruses. All three subtypes established persistent infection chains and became prevalent in the European pig population. They successively replaced the circulating classical swine H1N1 viruses of that time and gave rise to a number of reassortant viruses including the pandemic (H1N1) 2009 virus. All three European lineages have the capacity to infect humans but zoonotic infections are benign.

Animal models to assess the toxicity, immunogenicity and effectiveness of candidate influenza vaccines

INTRODUCTION

Every year, > 100 million doses of licensed influenza vaccine are administered worldwide, with relatively few serious adverse events reported. Initiatives to manufacture influenza vaccines on different platforms have come about to ensure timely production of strain-specific as well as universal vaccines. To prevent adverse events that may be associated with these new vaccines, it is important to evaluate the toxicity of new formulations in animal models.

AREAS COVERED

This review outlines preclinical studies that evaluate safety, immunogenicity and effectiveness of novel products to support further development and clinical trials. This has been done through a review of the latest literature describing vaccines under development.

EXPERT OPINION

The objective of preclinical safety tests is to demonstrate the absence of toxic contaminants and adventitious agents. Additional tests that characterize vaccine content more completely, or demonstrate the absence of exacerbated disease following virus challenge in vaccinated animals, may provide additional data to ensure the safety of new vaccine strategies.

SEROLOGICAL EVIDENCE FOR THE OCCURRENCE OF INFECTION WITH HUMAN INFLUENZA VIRUS IN SWINE

Antibodies capable of neutralizing human influenza virus were present in the sera of old swine on two New Jersey institution farms, but absent from the sera of young swine on the same farms. The old animals had lived through the winter of 1936-37 in which outbreaks of upper respiratory tract disease were prevalent among the human inmates of the two institutions, while the young swine studied were born long after these outbreaks. It is believed that the swine whose sera neutralized human influenza virus had undergone an unrecognized human influenza virus infection acquired from man. The possible bearing of these observations upon the theory that swine influenza was originally of human origin is discussed.

STUDIES ON THE NASAL HISTOLOGY OF EPIDEMIC INFLUENZA VIRUS INFECTION IN THE FERRET : I. THE DEVELOPMENT AND REPAIR OF THE NASAL LESION

A study has been made of the nasal histology in normal ferrets and in ferrets during and after infection with epidemic influenza virus. During the acute stage of infection the respiratory epithelium of the nasal mucous membrane undergoes necrosis with desquamation of the superficial cells and exudation into the air passages, and an inflammatory reaction occurs in the submucosa. Repair begins on the 4th day after infection, and from the 6th to the 14th day the respiratory area is covered successively by a transitional, a stratified squamous, and finally a stratified columnar epithelium. By the 21st day after infection the epithelium has been largely restored to normal but repair in the submucosa and cartilage is still in progress. The respiratory mucosa is substantially normal in structure 1 month after infection although minor abnormalities of cellular arrangement and type can still be distinguished.

SYNERGISTIC ACTION OF HEMOPHILUS INFLUENZAE SUIS AND THE SWINE INFLUENZA VIRUS ON THE CHICK EMBRYO

The synergistic effect of Hemophilus influenzae suis and swine influenza virus in the pig can be reproduced by the inoculation of these agents on the chorioallantoic membrane of 9 to 10 day old chick embryos. Two strains of human influenza virus that were studied failed to substitute for the swine virus in the synergistic reaction. No loss of synergistic effect was noted when the swine influenza virus was put through 11 chick embryo passages. Recently isolated and old stock strains of Hemophilus were equally able to enhance the effect of the virus. Heat-killed cultures of H. influenzae suis can be substituted for the bacterial component of the reaction. Infection of the embryo with swine influenza virus predisposes to infection with H. influenzae suis. The combination of H. influenzae suis and swine influenza virus causes a selective destruction of the embryo lungs, not produced by the individual components. This pneumonia exhibits the essential features of the natural disease.

Effect of the lesion due to influenza virus on the resistance of mice to inhaled pneumococci

1. The normal lung of the mouse possesses the power of reducing markedly its content of Type I pneumococci within 3 hours after inhalation of the organisms in the form of fine droplets. 2. Lungs with fully developed influenza viral pneumonia not only fail to reduce the pulmonary content of pneumococci administered in this manner but, on the contrary, support their growth. 3. After intrabronchial inoculation into mice, influenza virus multiplies rapidly in the lung within 24 hours. 4. Criteria have been established for distinction between true viral lesions of the lung and changes due to the inoculation of diluents as vehicles for the virus. 5. 24 hours after inoculation of virus, there are no macroscopic lesions in the lung and the microscopic changes are due to the diluent. 6. Presence and multiplication of the virus in the lung 24 hours after inoculation have no apparent effect on the power of the lung to reduce rapidly its content of inhaled pneumococci. 7. The effect of the virus in lowering resistance to secondary bacterial infection appears to be due to the presence of the lesion produced by the virus.

Bird flu, influenza and 1918: the case for mutant Avian tuberculosis

Influenza is Italian for "influence", Latin: influentia. It used to be thought that the disease was caused by a bad influence from the heavens. Influenza was called a virus long, long before it was proven to be one. In 2005, an article in the New England Journal of Medicine estimated that a recurrence of the 1918 influenza epidemic could kill between 180 million and 360 million people worldwide. A large part of the current bird-flu hysteria is fostered by a distrust among the lay and scientific community regarding the actual state of our knowledge regarding the bird flu or H5N1 and the killer "Influenza" Pandemic of 1918 that it is compared to. And this distrust is not completely unfounded. Traditionally, "flu" does not kill. Experts, including Peter Palese of the Mount School of Medicine in Manhattan, remind us that even in 1992, millions in China already had antibodies to H5N1, meaning that they had contracted it and that their immune system had little trouble fending it off. Dr. Andrew Noymer and Michel Garenne, UC Berkely demographers, reported in 2000 convincing statistics showing that undetected tuberculosis may have been the real killer in the 1918 flu epidemic. Aware of recent attempts to isolate the "Influenza virus" on human cadavers and their specimens, Noymer and Garenne summed that: "Frustratingly, these findings have not answered the question why the 1918 virus was so virulent, nor do they offer an explanation for the unusual age profile of deaths". Bird flu would certainly be diagnosed in the hospital today as Acute Respiratory Distress Syndrome (ARDS). Roger and others favor suspecting tuberculosis in all cases of acute respiratory failure of unknown origin. By 1918, it could be said, in so far as tuberculosis was concerned, that the world was a supersaturated sponge ready to ignite and that among its most vulnerable parts was the very Midwest where the 1918 unknown pandemic began. It is theorized that the lethal pig epidemic that began in Kansas just prior to the first human outbreaks was a disease of avian and human tuberculosis genetically combined through mycobacteriophage interchange, with the pig, susceptible to both, as its involuntary living culture medium. What are the implications of mistaking a virus such as Influenza A for what mycobacterial disease is actually causing? They would be disastrous, with useless treatment and preventative stockpiles. The obvious need for further investigation is presently imminent and pressing.

Role of hemagglutinin cleavage for the pathogenicity of influenza virus

Although human epidemics of influenza occur on nearly an annual basis and result in a significant number of "excess deaths," the viruses responsible are not generally considered highly pathogenic. On occasion, however, an outbreak occurs that demonstrates the potential lethality of influenza viruses. The human pandemic of 1918 spread worldwide and killed millions, and the limited human outbreak of highly pathogenic avian viruses in Hong Kong at the end of 1997 is a warning that this could happen again. In avian species such as chickens and turkeys, several outbreaks of highly pathogenic influenza viruses have been documented. Although the reason for the lethality of the human 1918 viruses remains unclear, the pathogenicity of the avian viruses, including those that caused the human 1997 outbreak, relates primarily to properties of the hemagglutinin glycoprotein (HA). Cleavage of the HA precursor molecule HA0 is required to activate virus infectivity, and the distribution of activating proteases in the host is one of the determinants of tropism and, as such, pathogenicity. The HAs of mammalian and nonpathogenic avian viruses are cleaved extracellularly, which limits their spread in hosts to tissues where the appropriate proteases are encountered. On the other hand, the HAs of pathogenic viruses are cleaved intracellularly by ubiquitously occurring proteases and therefore have the capacity to infect various cell types and cause systemic infections. The x-ray crystal structure of HA0 has been solved recently and shows that the cleavage site forms a loop that extends from the surface of the molecule, and it is the composition and structure of the cleavage loop region that dictate the range of proteases that can potentially activate infectivity. Here influenza virus pathogenicity is discussed, with an emphasis on the role of HA0 cleavage as a determining factor.

INDUCTION OF PARTIAL SPECIFIC HETEROTYPIC IMMUNITY IN MICE BY A SINGLE INFECTION WITH INFLUENZA A VIRUS

Schulman, Jerome L. (Cornell University Medical College, New York, N.Y.), and Edwin D. Kilbourne. Induction of partial specific heterotypic immunity in mice by a single infection with influenza A virus. J. Bacteriol. 89:170-174. 1965.-Mice infected 4 weeks previously with influenza A virus were found to be partially immune when challenged with influenza A2 virus. This partial immunity was demonstrated by reduced titers of pulmonary virus, decreased mortality, and less extensive lung lesions. A specific immunological basis for this protection was suggested by the absence of any protection in animals previously infected with influenza B virus when challenged with A2 virus, or in animals previously infected with influenza A virus when challenged with influenza B virus. Parenteral inoculation with inactivated influenza A virus did not induce partial immunity to A2 virus challenge. An accelerated rise of hemagglutinating-inhibiting antibody after A2 virus challenge was demonstrated in animals previously infected with influenza A virus.

Genetic divergence of the NS genes of avian influenza viruses

The nucleotide sequences of the NS genes of avian influenza A viruses, A/Chicken/Japan/24, A/Duck/England/56, A/Tern/South Africa/61, A/Duck/Ukraine/1/63, and A/Mynah/Haneda-Thai/76, were determined and compared among themselves and with two reported NS sequences of the avian viruses, A/FPV/Rostock/34 and A/Duck/Alberta/60/76. Thirty-six to two hundred forty base differences in the NS genes were found in pairwise comparisons among the viruses. The numbers of base differences in the NS genes increased with time, except A/Duck/Alberta/60/76 virus. However, the NS genes of the avian viruses did not change sequentially with time and were arranged in separate evolutionary lineages. When the NS genes of avian viruses employed in the present study were compared with those of human viruses, sequence similarity was confirmed (M. Baez, R. Taussig, J. J. Zarza, J. F. Young, P. Palese, A. Reisfield, and A. M. Skalka, 1980, Nucleic Acids Res. 8, 5845-5858). The numbers of base differences in the NS genes between avian viruses and the A/PR/8/34 virus were 61 to 83, and the NS gene of the oldest avian isolate, A/Chicken/Japan/24, was most closely related to that of the A/PR/8/34 virus. It was hypothesized that NS genes of human influenza viruses and those of some avian influenza viruses had been derived from a common ancestor gene.

[Pathologico-anatomic findings in sudden, unexpected death in children and adults with influenza A infection]

Thé following observations resulted from studies on forensic autopsy cases: In 76% of the adults and 55% of the infants the cases of unexpected sudden death without morphologically verifiable causes of death showed virologic evidence of recent influenza-A (H3N2)-infection. The pathologic findings corresponded with the findings in lethal infections with influenza-A viruses. Investigation of cases of sudden and unexpected death should always include virologic serum tests. The demonstration of IgM antibodies against influenza-A virus confirms that there was a recent infection. Death from influenza-A infections occurs also in the interepidemic periods.

Genetic relatedness between A/Swine/Iowa/15/30(H1N1) and human influenza viruses

The nucleotide sequences of the M and NS1 genes of influenza virus A/Swine/Iowa/15/30 (A/SW/IW/30)(H1N1) were determined with cloned DNAs and compared with reported sequences of human and avian influenza viruses. A/SW/IW/30 virus was found to be closely similar to A/PR/8/34(H1N1) virus in the nucleotide sequences of the M and NS1 genes, the base differences between the two strains being 64 out of 1027 nucleotides in the M gene and 52 out of 740 in the NS1 gene. Based on the assumptions that these two viruses were derived from a common ancestor and that the rate of base changes per year was the same in man and in swine, it was estimated that the progenitor virus was in circulation during the period from 1915 to 1920. This estimation was compatible with the epidemiological findings suggesting that the progenitor of the swine influenza virus was the agent of the 1918 influenza pandemic. Furthermore, the M and NS1 gene sequences of A/FPV/Rostock/34(H7N6) virus were much closer to those of A/SW/IW/30 and A/PR/8/34 viruses than to A/duck/Alberta/60/76(H12N5) virus, but not as close as the A/SW/IW/30 virus was to A/PR/8/34 virus.

[Influenza]

Influenza is the last great uncontrolled plague of mankind. Pandemics and epidemics occur at regular time intervals. The influenza viruses are divided into the types A, B and C and show unique variability of their surface antigens (hemagglutinin and neuraminidase). Influenza viruses of type A show the largest degree of antigenic variation which, in turn, resulted in the definition of a number of subtypes, each comprising many strains. By comparison, influenza viruses of types B and C exhibit much less variation of their surface antigens. As a consequence, no subtypes but many different strains have been recognized. The degree of antigenic variation correlates with the epidemiologic significance of the virus types, type A being the most and type C the least important. Two different kinds of antigenic variation have been recognized: In the case of minor variation of one or both surface antigens, the term "antigenic drift" is employed. Antigenic drift occurs with all three types of virus, it is caused by point mutations which increase the chance of survival of mutants in the diseased host. In addition, influenza A viruses show sudden and complete changes of their surface antigens in regular time intervals, resulting in the appearance of new subtypes. This event is called "antigenic shift". The mechanisms responsible for antigenic shift are poorly understood, only. In addition to the recycling of preceding subtypes, reassortment resulting from double infection of cells with strains of human and animal origin are considered possible explanations. By use of modern DNA recombinant technology, the base sequences of a series of virus genes and, as a consequence, the amino acid sequence of the corresponding antigens have been determined. By means of monoclonal antibodies, the antigenic structure of many influenza antigens has been further elucidated. It can be expected that further research on the molecular basis of antigenic variation could finally result in an understanding of the causal mechanisms. It is an outstanding feature of the epidemiology of influenza A viruses that a family of related strains prevails for a certain period of time and disappears abruptly as a new subtype emerges.(ABSTRACT TRUNCATED AT 400 WORDS)

A ge distribution of antibodies to animal influenza A viruses in human sera

A total of 394 sera from persons in different age-groups among the inhabitants of the Vladivostok area were studied by the haemagglutination-inhibition (HI) test for the presence of influenza antibodies. Each serum was examined against 12 antigens of influenza A virus of human (A0, A1, and 2 strains of A2) and animal (1 swine, 2 equine and 5 avian strains) origin. All the sera were collected 8-9 months after the outbreak of A2 influenza in 1965. Antibodies to some animal viruses were present: Swine/Iowa, Equi/2/Miami, Tern/South Africa and Chicken/Scotland strains; negative results were found to Equi/1/Prague, Duck/England and Duck/Czechoslovakia and fowl plague strains. The pattern of HI antibody distribution to animal strains showed an increase in the range in relation to age; the largest was found in the older age-group (70 years and over).The authors suggest that antibodies in the human sera to animal strains are not necessarily an indication of past infection with those strains.

REACTIONS OF MONKEYS TO EXPERIMENTALLY INDUCED INFLUENZA VIRUS A INFECTION : AN ANALYSIS OF THE RELATIVE ROLES OF HUMORAL AND CELLULAR IMMUNITY UNDER CONDITIONS OF OPTIMAL OR DEFICIENT NUTRITION

1. Macaca mulatta monkeys on a normal diet have proved resistant to intranasal but not to intratracheal inoculation of influenza virus. 2. Neutralizing antibodies appeared 8 to 10 days after inoculation with either living or heat-inactivated virus. The antibodies were noted to be still present as long as 9 months after infection with living virus. 3. A specific granulopenic leucopenia characteristically followed primary influenza virus inoculation, regardless of altered conditions of diet, exposure, and route of inoculation, but it was not observed in monkeys previously infected with the same virus, all of which invariably survived. 4. Nutritional deficiency and exposure to cold increased the susceptibility of monkeys on intranasal instillation of the virus; the leucopenia was profound and fatalities frequently occurred even though neutralizing humoral antibodies developed as promptly and in relatively the same titer as under optimum nutritional conditions.

SULFONAMIDE CHEMOTHERAPY OF COMBINED INFECTION WITH INFLUENZA VIRUS AND BACTERIA

1. Sulfonamide chemotherapy controls the bacterial component of combined infection with influenza virus and pneumococci in rats. 2. Reinstillation of fluid (broth, physiological salt solution) into the respiratory passages of mice several days after sublethal viral infection converts the viral infection into a lethal one. 3. Sulfonamide chemotherapy controls the bacterial component of combined bacterial and viral infection of mice, produced by intrabronchial inoculation of mixtures of bacteria and sublethal or lethal doses of virus. 4. Bacterial pneumonia may be superimposed upon sublethal viral infection in mice by inhalation of fine droplets of bacterial suspension several days after inoculation of virus. Normal mice inhaling fine droplets of bacterial suspension fail to develop obvious disease. 5. Sulfonamide chemotheiapy controls bacterial pneumonia superimposed on sublethal viral infection by inhalation of fine droplets of bacterial culture. 6. The secondary bacterial penumonia does not convert the sublethal viral infection into a lethal one. 7. If another pandemic of influenza occurs, it is probable that sulfonamide chemotherapy will be valuable in the treatment of secondary bacterial pneumonia and will be effective in lowering the case fatality rate if the viral component of the infection is not severe enough by itself to cause death.