MYCOVIRO - Orthomyxoviridae, Paramyxoviridae, Rubella

Similarities of ORTHOMYXOVIRIDAE & PARAMYXOVIRIDAE

•Myxoviruses
•Infect the respiratory tract

•Helical in symmetry

• Enveloped
• SS RNA

Segmented RNA is divided into?

8 pieces

Differences of ORTHOMYXOVIRIDAE & PARAMYXOVIRIDAE

• Number of segments

• Glycoprotein spikes

includes Ha and Na (Hemagglutinin and

Neuraminidase)

Orthomyxoviridae

its glycoprotein spikes cannot fuse cells – (Because there’s no glycoprotein F)

Orthomyxoviridae

includes Ha,Na,(G),F (Hemagglutinin, Neuraminidase, No H and N, Glycoprotein, Fusion)

Paramyxoviridae

• The (G) refers to the member of this family where there is no ??? and ??? but there’s a glycoprotein

• no H and N

This virus does not agglutinate, it has no neuraminidase

Paramyxoviridae

In ???, all of them have F (Fusion)

Paramyxoviridae

• Negative sense ss-RNA, segmented, helical, enveloped, and pleomorphic

ORTHOMYXOVIRIDAE

o 8 pieces of RNA (in the middle)

o Helical nucleocapsid
o Envelope

ORTHOMYXOVIRIDAE

Inner layer of ORTHOMYXOVIRIDAE

M1 Protein

Outer Layer of ORTHOMYXOVIRIDAE

Lipid bilayer membrane

In ORTHOMYXOVIRIDAE, the envelope is derived from the host cell membrane - though it gets a membrane from the infected host cell to make an envelope, it becomes virus-specific because of the (???)

glycoprotein

Glycoproteins of ORTHOMYXOVIRIDAE

Hemagglutinin and Neuraminidase (H and N)

RNA with a protein is called the

RNP OR Ribonucleoprotein

In ?viridae, the RNA is associated with a protein

ORTHOMYXOVIRIDAE

Only 1 virus under Orthomyxoviridae

INFLUENZA VIRUS

True or False: In Orthomyxoviridae, there is also an associated polymerase within the virion.

True

Under each of INFLUENZA in Orthomyxoviridae, there may be subtypes which are defined by the ???? component

H and N component

Strains of Influenza Virus (Orthomyxoviridae) are determined by

hemagglutinin and neuraminidase

Examples of Strains of Influenza Virus (Orthomyxoviridae)

e.g., H1N1, H5N1

Influenza virus – member of the family ????

Orthomyxoviridae

Of all the respiratory viruses known to infect humans, WHAT is the cause of the greatest number of serious acute illnesses

Influenza Virus (Orthomyxoviridae)

More than ???? hospitalizations and more than 30,000 deaths occur in the United States every year. (Influenza Virus (Orthomyxoviridae)

200,000

three types of influenza viruses are known to infect humans

(A, B, and C),

Inlfuenza type which usually causes subclinical infections and is not known to pose a threat to human health.

type C

Influenza virus A, influenza virus B, and influenza virus C can be distinguished based on the ???? differences in the matrix protein (M) and the nucleoprotein (NP).

antigenic differences

What are the antigenic differences of the types of influenza?

matrix protein (M) and the nucleoprotein (NP).

is further subdivided based on the major surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA). Influenza

Influenza virus A

naturally infects many bird species, swine, seals, felines, and horses.

Influenza virus A

influenza only known to infect humans.

Influenza B and C

Projecting from the envelope of the virion are the two major surface glycoproteins,

hemagglutinin and neuraminidase (HA and NA)

rod-shaped spikes that enable viral attachment to sialic acid–containing cellular receptors.

HA proteins

mushroom-shaped spikes.

NA proteins

They facilitate the release of mature virions from infected cells and assist in viral movement through mucus to adjacent cells.

NA proteins

• NA proteins

In, Orthozyvxoviriidae, Sixteen different HA molecules and nine different NA molecules have been identifie

in, Orthomyxoviriidae, all of the different viral protein antigenic types can be found in the ????.

avian species

However, only ?? currently circulate in the human population.

H1, H2, H3, and N1 or N2

The H of influenza virus is used to attach to specific surface receptors ??

sialic acid

Viruses can infect cells only if there is a specific surface receptor – without the receptor, = ???

no infection

What is the receptor of influenza virus?

Sialic acid

Sialic acid found in the ???

respiratory tract

During an entry of an envelope virus to a host cell, the

envelope fuses with the membrane which is facilitated by ???

hemagglutinin

True or False: Anti-Hemagglutinin antibodies are not protective

False

Which is LEAST accurate concerning hemagglutinin of influenza virus?

Anti-Hemagglutinin antibodies are not protective

If hemagglutinin is for attachment (sialic acid): Neuraminidase is for ???

CLEAVAGE

It causes cleavage of the sialic acids from the glycoprotein

NEURAMINIDASE

Cleaves sialic acid on glycoproteins during budding

neuraminidase

After the virus has multiplied in the cell, it will be released by ??? of the virus from the host cell membrane

budding of the virus

Facilitates release of the virus by budding from infected cells

NEURAMINIDASE

Can however be inhibited by antiviral agents.

NEURAMINIDASE

Inhibitors of neuraminidase.

Zanamivir (Relenza) & Oseltamivir

Mechanism of anti-viral agents (Neuraminidase in Influenza Orthomyxoviridae)

They attach to neuraminidase so that it will not be able to cleave sialic acid – the virus remains attach to the host cell and therefore, the virus will not continue to multiply

also produced against neuraminidase but they are not protective unlike anti-hemagglutinin

Anti-bodies

INFLUENZA VIRUS

a highly pathogenic virus. results in greater mortality than

infection with influenza A H1N1 or influenza B.

Influenza A H3N2

Determine if pandemic, epidemic, or sporadic: Influenza A

Pandemic, Epidemic

Determine if pandemic, epidemic, or sporadic: Influenza C

Sporadic

Determine if pandemic, epidemic, or sporadic: Influenza B

Epidemic

Determine if shift or drift: Influenza C

Drift

Determine if shift or drift: Influenza A

shift, drift

Determine if shift or drift: Influenza B

Drift

Determine if Man or Animals: Influenza B

Man

Determine if Man or Animals: Influenza A

Man , Animals

Determine if Man or Animals: Influenza C

Man

o Only one that can infect animals
o Infection in animals is associated to cause pandemic

• Influenza A

Man’s highly ??? to influenza virus – once exposed, you’ll surely get infected (get vaccine) • No natural resistance to influenza

susceptible

Man has no natural resistance to ?

influenza

a major change

Antigenic Shift

a minor change

Antigenic Drift

Shift is only seen in ?

Influenza A

The infection of animals is important in the epidemiology of influenza. It is also responsible for the antigenic change that occurs in influenza A virus called ?

antigenic shift

Drifts are usually involved in

epidemics or sporadics

is usually responsible for pandemic or worldwide spread of infections

Antigenic shift

not common

Influenza C

less common than

influenza A

Influenza B

Majority of cases of influenza are caused by

influenza A

First to cause lives of millions to death before SARS-COV 2

Influenza A

Influenza A Can be transmitted through

respiratory droplets or respiratory inhalation

Animals that are infected by influenza:

o Birds/ avian

o Pigs/ swine

o Horses (equine influenza)

responsible for the annual epidemics and periodic pandemics of

influenza infection worldwide

ANTIGENIC VARIATIONS

WHERE DO “NEW” HA & NA COME FROM?

● Related to animals

True or False: Strains directly affect each other in influenza (orthomyxoviridae)

False, do not directly affect ex. Horses (equine influenza)

Usually:

○ Human strain will infect humans only

○ Strains that infect animals like birds and ducks will infect birds only

○ Strains that infect ducks does not infect man and vice versa

A case wherein both human and bird strain can infect and multiply. The pig can be considered as a mixing bowl of the influenza virus. Responsible for this is?

Antigenic Shift

● Due to genetic reassortment of the genome segments

● Results in a change in H or N Agor both

● New strain is formed containing both genomes

Antigenic Shift

Antigenic Shift is cyclic and happens every ??? yrs

every 10 years

The mixture of the two types of segments of RNAs is called

Genetic Reassortment

The cycle of the virus repeats after ?? due to the antigenic shift through genetic reassortment

10 years

True or False: The immunity from the old virus does not protect the population from the new one.

True

True or False: It is possible to be immune to influenza virus.

False, difficult to become completely immune

A minor change due to accumulation of point mutations in the H (hemagglutinin) gene

Antigenic Drift

Results in amino acid changes in the H Ag but H remains the same proteinc

Antigenic Drift

Ao(HoN1) → A1 (H1N1)

Antigenic Shift

A1 (H1N1) → A1 (H1N1)

Antigenic Drift

Usually causes epidemics rather than

pandemics

Antigenic Drift

Antigenic Drift occurs more frequently - Periodic (every ???? years) change

1 or 2 years

In Antigenic Drift, how does the manufacturer create vaccine

predicts the movements of the virus or the changes it will take

is a much more dramatic change in the viral genome and only occurs with influenza A viruses

Antigenic shift