Man Sneezing Germs Shown Spreading

Man Sneezing Germs Shown Spreading

This photograph captures a sneeze in progress, revealing the plume of salivary droplets as they are expelled in a large cone-shaped array from this man’s open mouth, thereby, dramatically illustrating the reason one needs to cover hios/her mouth when coughing, or sneezing, in order to protect others from germ exposure.

Man Sneezing Germs Shown Spreading

Man Sneezing Germs Shown Spreading

This photograph captures a sneeze in progress, revealing the plume of salivary droplets as they are expelled in a large cone-shaped array from this man’s open mouth, thereby, dramatically illustrating the reason one needs to cover hios/her mouth when coughing, or sneezing, in order to protect others from germ exposure.

Hong Kong Flu Virus Virions (H3N2 Subtype)

Hong Kong Flu Virus Virions (H3N2 Subtype)

Hong Kong Flu Virus Virions (H3N2 Subtype)

(All Images are for Editorial Use Only)

This negatively-stained transmission electron micrograph (TEM) revealed the presence of a number of Hong Kong flu virus virions, the H3N2 subtype of the influenza A virus. This virus is a Orthomyxoviridae virus family member, and was responsible for the flu pandemic of 1968-1969, which infected an estimated 50,000,000 people in the United States, killing 33,000. Note the proteinaceous coat, or capsid, surroundind each virion, and the hemagglutinin-neuraminidase spikes, which differ in terms of their molecular make-up from strain to strain.

There are many different subtypes of type A influenza viruses. These subtypes differ because of changes in certain proteins on the surface of the influenza A virus (hemagglutinin [HA] and neuraminidase [NA] proteins). There are 16 known HA subtypes and 9 known NA subtypes of influenza A viruses. Many different combinations of HA and NA proteins are possible. Each combination represents a different subtype. All known subtypes of influenza A viruses can be found in birds.

Influenza A Virions

Influenza A Virions

Influenza A Virions

This negative-stained transmission electron micograph (TEM) depicted a number of influenza A virions.

There are three types of influenza viruses: A, B and C. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. The emergence of a new and very different influenza virus to infect people can cause an influenza pandemic. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics. For a colorized version of this image see PHIL 11702.

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H) and the neuraminidase (N). There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes. Influenza A viruses can be further broken down into different strains. Current subtypes of influenza A viruses found in people are influenza A (H1N1) and influenza A (H3N2) viruses. In the spring of 2009, a new influenza A (H1N1) virus emerged to cause illness in people. This virus was very different from regular human influenza A (H1N1) viruses and the new virus has caused an influenza pandemic.

Micrograph of Neuraminidase and Hemagglutinin “spikes”

Micrograph of Neuraminidase and Hemagglutinin “spikes”

Micrograph of Neuraminidase and Hemagglutinin “spikes”

This negatively-stained transmission electron micrograph (TEM) depicted a small grouping of a number of influenza A virions, which also revealed at this very high magnification, the neuraminidase and hemagglutinin “spikes” protruding from the virions’ proteinaceous capsid coats. At its core, the genome consists of eight single-stranded segments of a negative-sense RNA ((-) ssRNA). Influenza A virions can be observed as being both spherical and filamentous in nature. Each strand is enclosed in, or “encapsidated” inside the viral nucleoprotein, thereby, forming what is known as the ribonucleoprotein (RNP) particle.