MICROBIOLOGY PPT LECTURE NOTES | Karya Tulis Ilmiah

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Respiratory

viruses

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Categories of Respiratory Viruses

• Orthomyxoviridae: Influenza virus

• Paramyxoviridae : Parainfluenza virus; Mumps virus; Measles; Respiratory

syneytical virus

• Togaviridae: Rubella Virus

• Coronaviridae: Corona Virus; SARS virus • Adenoviridae : human Adenovirus

• picornaviridae: Rhino Virus; • Reoviridae:

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Influenza virus

Orthomyxoviridae: Influenza virus

Influenza is a disease caused by Influenza virus ,a member of the

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Genome

of Influenza virus

• 8 negative sense RNA nucleocapsid segments

• The 'RNP' (RNA + nucleoprotein) is in a helical form with the 3 polymerase

polypeptides associated with each segment.

• _{The segmented genome promotes genetic}

diversity caused by mutation and

reassortment of segments on infection with two different strains

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Virion

• spherical/ovoid, 80-120nm diameter,

• The inner side of the envelope is

lined by the matrix protein, stable type-specific.

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Virion

• The outer surface of the particle consists of a lipid envelope from which project

prominent glycoprotein spikes of two

types, the haemagglutinin, ~135Å trimer (HA), and neuraminidase, ~60Å tetramer (NA).

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Haemagglutinin (HA)

• Encoded by RNA segment #4

• Can agglutinate red blood cells - hence the nomenclature

• Cleavage by host-cell protease is required (resulting in HA1 and HA2) for infection to occur

• Hemagglutinin glycoprotein is the viral

attachment protein and fusion protein , and it elicits neutralizing , protective antibody

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Neuraminadase (NA)

• Encoded by RNA segment #6

• Enzyme that uses neuraminic (sialic) acid as a substrate

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ORTHOMYXOVIRUSES

M1 protein

helical nucleocapsid (RNA plus NP protein)

HA - hemagglutinin

polymerase complex lipid bilayer membrane

NA - neuraminidase

type A, B, C : NP, M1 protein sub-types: HA or NA protein

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Replication

• Influenza transcribe and replicates its genome in the target cell nucleus

• assemble and buds from the plasma

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Antigen

• Soluble antigens: include ribonucleoprotein and M protein which are much stable in antigenicity. • Surface antigens: include HA and NA which are

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Types

• Influenza viruses are divided into 3 groups determined by the ribonucleoprotein (RNP) antigen and M antigen:

• Group A - This group is the cause of

epidemics and pandemics and has an avian intermediate host (IH)

Group B - This group causes epidemics and has no IH

Group C - This group does not cause epidemics and causes mild disease

15 TYPE A ++++ yes yes yes shift, drift yes sensitive sensitive 2

severity of illness animal reservoir human pandemics human epidemics antigenic changes segmented genome amantadine, rimantidine zanamivir surface glycoproteins TYPE B ++ no no yes drift yes no effect sensitive 2 TYPE C + no no no (sporadic) drift yes no effect (1)

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Subtypes

• According to antigenicity of HA and NA,

influenza virus is divided into subtypes such as HnNm( H1N2, et al )

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Variation and Epidemiology

Antigenic drift: median or small epidemic. Antigenic shift:large scale epidemic.

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Antigenic Shift Of

Influenza virus

• _{Reassortment of genes is a common}

feature of Influenza A, but not B or C

• When two different "A" viruses infect the same cell, their RNA segments can

become mixed during replication

• New viruses produced in this way may survive due to a selective advantage within the population

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Antigenic Drift of Influenza

Virus

•Constant mutations in the RNA of

influenza which lead to polypeptide mutations

•Changes are less dramatic than those induced by Shift

•If these mutations affect HA or NA they may cause localized epidemics

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where do “new” HA and NA come

from?

• 13 types HA • 9 types NA

– all circulate in birds

• pigs

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where do “new” HA and NA come

from?

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why do we not have influenza B

pandemics?

• so far no shifts have been

recorded • no animal

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Resistence

• The particles are relative labile ,not resistant to drying, etc.

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Pathogenesis

• Influenza is characterised by fever, myalgia, headache and pharyngitis. In addition there may be cough and in severe cases,

prostration. There is usually not coryza 鼻炎 (runny nose) which characterises common cold infections.

• Infection may be very mild, even

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Transmission

• Source of infection: patients and carriers.

• AEROSOL

– 100,000 TO 1,000,000 VIRIONS PER DROPLET

28 Aerosol

Inoculation Of virus

29 NORMAL TRACHEAL MUCOSA

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SYMPTOMS

• FEVER

• HEADACHE

• MYALGIA( 肌痛 ) • COUGH

• RHINITIS( 鼻炎 )

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PULMONARY COMPLICATIONS

• CROUP (YOUNG CHILDREN)

• PRIMARY INFLUENZA VIRUS PNEUMONIA • SECONDARY BACTERIAL INFECTION

– _{Streptococcus pneumoniae} – _{Staphlyococcus aureus}

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NON-PULMONARY COMPLICATIONS

• myositis (rare, > in children, > with type B)

• cardiac complications • liver and CNS

– Reye’s syndrome

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Lab Diagnosis

• Viral detection:

Respiratory secretions

( direct aspirate , gargle , nasal washings ) 1. Cell culture in primary monkey kidney or

madindarby canine kidney cells 2. Hemagglutination (inhibition) Hemadsorption (inhibition)

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• Serology

hemagglutination inhibition Hemadsorption inhibition ELISA

immunofluoresence complement fixation.

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Prevention

• Vaccines at best give about 70% protection. They may sometimes not be effective against the most recently evolved strains because the rate of evolution outpaces the rate at which

new vaccines can be manufactured.

• _{This constant antigenic change down the}

years means that new vaccines have to be made on a regular basis.

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Types of Vaccine

• Killed Whole Virus

Rather pyrogenic, not used today.

• Live Virus

Attenuated strains were widely used in Russia but not elsewhere.

• Virus Subunit

HA extracted from recombinant virus forms the basis of today's vaccines.

For example, the WHO Recommendation for Influenza Vaccine, 1995-1996, contains two A strains and one B strain:-[A / Singapore / 6 / 86 (H1N1)+A / Johannesburg / 33 / 94 (H3N2) +B / Beijing / 84 / 93 ]

• Synthetic

Much research is being done to try and find a neutralising epitope that is more stable, and can therefore be used for a universal vaccine.

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40 PB2 PB1 PA HA NA NP M NS PB2 PB1 PA HA NA NP M NS PB2 PB1 PA HA NA NP M NS Attenuated Donor Master Strain New Virulent Antigenic Variant Strain

X

Attenuated Vaccine Strain: Coat of Virulent strain with Virulence Characteristics of Attenuated Strain

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Treatment

• Amantadine and rimantadine are active against influenza A viruses. The action of these closely related agents is

complex and incompletely understood, but they are believed to block cellular membrane ion channels, and inhibit an uncoating step and target the M2

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PREVENTION - DRUGS

• RIMANTADINE 金刚乙胺 (M2)

• type A only

• AMANTADINE 金刚烷胺 (M2)

• type A only

• ZANAMIVIR (NA)

• types A and B, not yet approved for prevention but studies show effective

• OSELTAMIVIR (NA)

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TREATMENT - DRUGS

• RIMANTADINE (M2)

• type A only, needs to be given early

• AMANTADINE (M2)

• type A only, needs to be given early

• ZANAMIVIR (NA)

• types A and B, needs to be given early

• OSELTAMIVIR (NA)

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OTHER TREATMENT

• REST, LIQUIDS, ANTI-FEBRILE AGENTS

(NO ASPIRIN FOR AGES 6MTHS-18YRS)

• BE AWARE OF COMPLICATIONS AND TREAT APPROPRIATELY

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Paramyxoviridae

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Paramyxoviridae

• Genus Human pathogen

• Morbillivirus Measles virus

• Paramyxovirus Parainfluenza viruses,

Mumps virus

• _{Pneumovirus Respirtory syncytical}

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Virion

Virion

• Large virion consists of a negative RNA

genome in a helical nucleocapsid surrounded by an enevlope containing a viral attachment protein

• HN of paramyxovirus and mumps virus has hemagglutinin and neuraminidase.

• H of measles virus has hemagglutinin activity • G of RSV lacks these activities

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M protein

helical nucleocapsid (RNA plus NP protein)

HN/H/G glycoprotein SPIKES

polymerase complex

lipid bilayer membrane

F glycoprotein SPIKES

PARAMYXOVIRUSES

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PARAMYXOVIRUS FAMILY

properties of attachment protein

GENUS GLYCOPROTEINS TYPICAL MEMBERS

Paramyxovirus

genus HN, F HPIV1, HPIV3 Rubulavirus

Genus HN, F HPIV2, HPIV4 mumps virus Morbillivirus

genus H, F measles virus Pneumovirus

genus G, F

respiratory

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Replication , Pathogenesis and Immunity

• Virus replicates in the cytoplasm

• Virions penetrate the cell by fusion with the plasma membrane

• Viruses induce cell-cell fusion, causing multinucleated giant cells

• Paramyxoviridae are transmitted in respiratory

droplets and initiate infection in the respiratory tract • Cell-mediated immunity causes many of the

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MMR vaccine

• Composition : live attenuated virus Measles / Mumps / Rubella

• Vaccination schedule: at 15-24 months and at 4 to 6 years or before junior high school • Efficiency: 95% lifelong immunization with a

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Measles virus

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Pathogenesis and Immunity

• Childhood infection almost universal, protection resulting from this is probably lifelong. Both man and wild monkeys are commonly infected

• In culture, produces characteristic intranuclear inclusion bodies and syncytial giant cells.

• Transmission and initial stages of disease similar to mumps, but this virus can also infect via the eye

and multiply in the conjunctivae. Viraemia following primary local multiplication results in widespread distribution to many organs.

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Pathogenesis and Immunity

• After a 10-12 day incubation period

• Dry cough, sore throat, conjunctivitis (virus may be excreted during this phase!), followed a few days later by the characteristic red, maculopapular rash and Koplik's spots

• Towards the end of the disease, there is extensive, generalized virus infection in lymphoid tissues and skin.

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DISSEMINATED SPREAD

• LONGER TIME FOR SYMPTOMS

• IMMUNE RESPONSE • IF SYMPTOMS DUE

TO IMMUNE

RESPONSE, USUALLY INFECTIOUS PRIOR TO SYMPTOMS

Adapted from Mims, Playfair, Roitt, Wakelin and Williams (1993) Medical Microbiology

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MEASLES - Koplik’s spots

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Koplik's spots

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MEASLES - RASH

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DISEASE

• FEVER

• RESPIRATORY TRACT SYMPTOMS

• rhinorrhea, cough

• KOPLIK’S SPOTS

• MACULOPAPULAR RASH

• T-cells ->endothelial cells

• CONJUNCTIVITIS

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MEASLES GIANT CELL PNEUMONIA

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MEASLES ENCEPHALITIS

• 1/1000 cases • sequelae

– deafness – seizures

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SSPE

• sub-acute sclerosing panencephalitis

– inflammatory disease – defective virus

• early infection with measles is a risk factor • rare (7/1,000,000 cases of measles)

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Treatment

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Prevention

• Both live and killed vaccines exist.

Vaccination with the live attenuated vaccine has been practised since the 1960's with a dramatic decline in the incidence of the

disease .

• Trivalent live attenuated vaccine (MMR) usually given - all of these viruses best avoided during pregnancy!

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Mumps virus

（腮腺炎病毒）

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Mumps virus

• Droplets spread the infection via saliva and secretions from the respiratory

tract.

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Mumps virus

• Malaise and fever is followed within a day by

painful enlargement of one or both of the parotid (salivary) glands

• A possible complication in males after puberty is

orchitis - painful swelling of one or both testicles. • Inflammation of the ovary and pancreas can also

occur.

• Disease is usually self-limiting within a few days • Aseptic meningitis (usually resolving without

problems) or postexposure encephalitis (can prove fatal) are the most serious complications

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Prevention and treatment

• Treatment: none (passive immunization has been used).

• Prevention: one invariant serotype therefore vaccines are viable - both

formalin-inactivated and live attenuated exist, the latter now being widely used- see MMR.

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MUMPS

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Parainfluenza virus

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Important Characteristics

• Typing: Four types (1-4) : distinguished antigenically, by cytopathic effect, and pathogenically

• Hemeagglutinin and fusion F protein is found in the envelope

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Pathogenesis and Immunity

• Cause acute respiratory infections of

man ranging from relatively mild

influenza-like illness to bronchitis, croup

(narrowing of airways which can result

in respiratory distress) and pneumonia;

common infection of children.

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Lab Diagnosis

• Nasopharynx specimen is culture in a

surrogate cell line in AGMK. Infected cell are detected by hemeadsorption or DFA

• DFA also can be done rapidly to identify the agent in direct specimen

• Serotypes 1-3 are comfirmed by hemeagglutination inhibition using standardized antisera

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Treatment

• No antiviral therapy is available

• Nursing the patient in a humidified atmosphere was commonly advised

• Dexamethasone 地塞米松 and budesonide

布德松 have been approved ( for outpatient treatments)

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Prevention

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Respiratory syncytial virus

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Important Characteristics

• RSV is highly infectious, transmission by respiratory secretions.

• Primary multiplication occurs in epithelial cells of

URT producing a mild illness. In ~50% children less than 8 months old, virus subsequently spreads into the L.R.T. causing bronchitis, pneumonia and croup. • Has been suggested as a possible factor in cot

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Pathogenesis and immunity

Disorder Age

Bronchiolitis Fever, cough, dyspnea, and pneumonia, cyanosis in children younger or both than 1 year

Febrile rhinitis Children and pharyngitis

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Lab Diagnosis

• DFA

• Cell culture of nasopharyngeal specimen • A rise in antibody titre using ELISA

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Treatment

• Ribavirin aerosol( 三 ( 氮 ) 唑核苷 , 病毒唑 ) is recommended for pneumonia in infants

• RSV - IGIV has been approved for infants born prematurely

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Prevention

• Currently no effective vaccine! Also, infection does not result in lasting protection (c.f.

mumps, measles) therefore repeated

infections ('colds') occur throughout life - usually without serious consequences in adults.

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Adenoviruses

（腺病毒）

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General Concepts

• Most Adenovirus infections involve either the respiratory or gastrointestinal tracts or the

eye.

Adenovirus infections are very common, most are asymptomatic. Most people have been infected with at least 1 type at age 15.

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Adenovirus

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Important

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Replication

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Pathogenesis and Immunity

• _{Disease: At Risk:}

• Acute Respiratory Illness Military recruits, boarding schools,

• Pharyngitis Infants

• Gastroenteritis Infants • Conjunctivitis All

• Pneumonia Infants, military recruits • Keratoconjunctivitis All

• Acute Haemorrhagic Cystitis Infants

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swimming pool conjunctivitis

( 游泳池结膜炎

;

红眼病 )

• Eye infections characterized by a mild conjunctivitis "swimming pool

conjunctivitis" are caused by

adenoviruses and have been linked to transmission in contaminated

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Lab Diagnosis

• Isolation of adenovirus can be accomplished in cell cultures derived from epithelial cells

• Immunoassays, including fluorescent antibody and enzyme-linked immunosorbent assays,

PCR can be used to detect and type the virus in clinical samples and tissue cultures

• Serological assays such as CFA, HI, EIA and neutralization techniques have been used to detect specific antibodies.

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Treatment

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Virion structure

• S-Spike

glycoprotein:

receptor binding, cell fusion, major antigen • M-Membrane glycoprotein: transmembrane - budding & envelope formation

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Pathogenesis and Immunity

• These viruses infect a variety of mammals & birds. The exact number of human isolates are not known as many cannot be grown in culture.

• They cause: common colds and have been implicated in gastroenteritis in infants.

• Transmitted by aerosols of respiratory secretions

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Rhinovirus

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Important Characteristics

• Rhinoviruses are picornaviruses similar to

enteroviruses but differ from them in having a buoyant density in cesium chloride of 1.40

g/ml and in being Acid-labile

• _{Rhinoviruses are isolated commonly from}

the nose and throat but very rarely from feces.

• _{These viruses cause upper respiratory}

tract infections, including the common cold

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Reovirus

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Important Characteristics

• Virion: Icosahedal, 60-80nm in diameter, double capsid shell

• Genome: dsRNA • Envelope: none

• Diseases: Acute respiratory tract infection and Gastrointestinal infections