Coronavirus

Virus classification

Phylum                 incertae sedis

Order                   Nidovirales

Family                   Coronaviridae

Subfamily             Orthocoronavirinae

Genus                   Alphacoronavirus (Alpha-CoV)

Betacoronavirus (Alpha-CoV)

Gammacoronavirus (Alpha-CoV)

Deltacoronavirus (Alpha-CoV)

Species of Alphacoronavirus

Human coronavirus 229E, Human coronavirus NL63, Miniopterus bat coronavirus 1 etc.

Species of Betacoronavirus

Human coronavirus HKU1, Severe acute respiratory syndrome-related coronavirus (SARS-CoV), Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), Middle East respiratory syndrome-related coronavirus (MERS) etc.

Species of Gammacoronavirus

Infectious bronchitis virus etc.

Species of deltacoronavirus

Bulbul coronavirus HKU11 etc.

There are seven strains of human coronavirus, four strains of which produce the generally mild symptoms of the common cold:

1.   Human coronavirus OC43 (HCoV-OC43)

2.   Human coronavirus HKU1

3.   Human coronavirus NL63 (HCoV-NL63, New Haven coronavirus)

4.   Human coronavirus 229E (HCoV-229E)

and three strains cause severe symptoms:

1.   Middle East respiratory syndrome-related coronavirus (MERS-CoV), previously known as novel coronavirus 2012 and HCoV-EMC

2.   Severe acute respiratory syndrome coronavirus (SARS-CoV or "SARS-classic")

3.   Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), previously known as 2019-nCoV or "novel coronavirus 2019"

Some interesting facts about SARS-CoV2:

·        Previously it was known as 2019 novel coronavirus (2019-nCoV)

·        SARS-CoV2 is responsible for pandemic COVID-19

·        Outbreak of SARS-CoV2 is declared as pandemic by WHO on March 11, 2020.

·        It is the seventh known coronavirus to infect people, after 229E, NL63, OC43, HKU1, MERS-CoV, and the original SARS-CoV.

·        Its transmission occurs by respiratory droplets like cough and sneeze within the range of 2 metre.

·        Size of SARS-CoV2 is 50-200nm in diameter.

·        SARS-CoV-2 has four structural proteins, known as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins; the N protein holds the RNA genome, and the S, E, and M proteins together create the viral envelope.

·        Spike protein is responsible for attachment of virus to host membrane.

·        Genome of SARS-CoV2 is positive-sense single-stranded RNA (+ssRNA).

·        Its genome is of 30kb length.

·        SARS-CoV2 bind with angiotensin converting enzyme2 (ACE2) receptors of human cells and enter into cells.

COVID-19 Update (till March 22, 2020 at 7:00 PM IST)

Total Coronavirus Cases: 317,298

Deaths:13,642

Recovered: 95,949

Active cases		Closed cases
207,707 Currently Infected Patients		109,591 Cases which had an outcome:
197,565 (95%) in Mild Condition	10,142 (5%) Serious or Critical	95,949 (88%) Recovered / Discharged	3,642 (12%) Deaths

COVID-19 Update (till March 22, 2020 at 5:30 AM IST)

Total cases	New cases	Total deaths	New deaths	Total recovered	Active cases	Serious, critical	Total cases/1M population
360	28	7	2	24	329		0.3

Outbreak of Coronavirus related diseases

Outbreak	Virus
SARS, 2003	SARS-CoV
MERS, 2012	MERS-CoV
MERS, 2015	MERS-CoV
MERS, 2018	MERS-CoV
COVID-!9	SARS-CoV2

Source:  https://www.wikipedia.org/

  https://www.worldometers.info/coronavirus/

  https://www.who.int/

Problems

Definition of Pandemic, Endemic, Epidemic and Syndemic

Pandemic (from Gree pan "all" and demos "people") is a disease epidemic that has spread across a large region, viz. multiple continents, or worldwide. A pandemic is an epidemic occurring on a scale that crosses international boundaries, usually affecting a large population.

Endemic (from Greek en "in, within" and demos "people") an infection is said to be endemic in a population when that infection is constantly maintained at a baseline level in a geographic area without external inputs.

Epidemic An epidemic (from Greek epi "upon or above" and demos "people") is the rapid spread of disease to a large population in given population within a short period of time.

A syndemic or synergistic epidemic is the aggregation of two or more concurrent or sequential epidemics or disease clusters in a population with biological interactions, which exacerbate the prognosis and burden of disease.

Multiple choice questions on Cell Junction

1- A skin disease pemphigus, in this disease affected individuals make antibodies against one of their own non classical cadherine of desmosomes. These antibodies bind to desmosomes and disrupt it, that hold their epidermal cells (keratinocytes) together – 

a- Cause severe blistering of body fluids into the loosened epithelium  

b- Block the exchange of materials in these cells

c- Disruption of gap junction 

d- All of the above 

2- Protein claudins are essential for tight junction, mice that lack claudin-1 gene fail to make tight junction between cells epidermal layer of skin; as a result 

a- Skin become loose due to accumulation of fluid, and baby mice die

b- Skin remain normal

c- baby mice die within a day after birth, due to lose of water rapidly by evaporation through the skin

d- baby mice servive with less fluid

3- In kidney epithelial cells, a specific claudin is found which is needed to reabsorb mg++ from urine to blood, mutation in claudin gene cause 

a- Mg++ reabsorb through other protein which allow reabsorption 

b- Excessive lose of mg++ ion in the urine

c- No effect because there is no reabsorption through claudin, it’s a protein of tight junction

d- Both a & c

4- Gap junction have channel forming protein namely connexins & innexins. ----- have connexins, ----- have innexins

a- Humans, other mammals

b- Mammals, birds

c- Vertebrates, invertebrates

d- Chordates, hemichordates

5- A rare human genetic disease, deficiency of dermatan sulfate disaccharide ( a type of GAGs) the affected individuals have-

a- Short stature, a prematurely aged appearance, and generalized defects in their skin, joints, muscles, and bones.

b- Normal face & stature with a weak bone

c- Only defect in skin

d- No effect 

6- Defect / dificiency of type I collagen lead to mutant phenotype – 

a- Severe bone defects, fractures ( osteogenesis imperfecta )

b- Fragile skin

c- Cartilage deficiency, dwarfism ( chondrodysplasia )

d- Osteoarthritis  

7- Defect / deficiency of types II collagen lead to mutant phenotype –

a- Severe bone defects, fractures ( osteogenesis imperfecta )

b- Fragile skin

c- Cartilage deficiency, dwarfism ( chondrodysplasia )

d- Osteoarthritis  

8- Defect / deficiency of types III collagen lead to mutant phenotype –

a- Severe bone defects, fractures ( osteogenesis imperfecta )

b- Fragile skin, loose joint, blood vessels prone to rupture ( Ehlers-Danlos syndrome ) 

c- Cartilage deficiency, dwarfism ( chondrodysplasia )

d- Osteoarthritis  

9- Type XI collagen which fibril associates with type I, a defect or deficiency of this collagen types lead to mutant phenotype –

a- Fragile skin

b- Cartilage deficiency, dwarfism ( chondrodysplasia )

c- Osteoarthritis

d- Myopia, blindness

10- Type IX collagen which form lateral association with type II, present in -----, defect or deficiency of this collagen cause -----

a- Cartilage, osteoarthritis 

b- Bone, osteoarthritis

c- Epithelium, fragile skin

d- All of the above

Answers: 1-a, 2-c, 3-b, 4-c, 5-a, 6-a, 7-c, 8-b, 9-d, 10-a

Contributed by: Ms. Nargis K.

Multiple choice questions

1)    A synthetic nucleotide analogue, used during organ transplantation as a immunosuppressant to avoid immunologic rejection of grafts is

(A)  Theophylline

(B)   Cytarabine

(C)   6-Mercaptopurine

(D)  4-Hydroxypyrazolopyrimidine

2)    Carbonic anhydrase enzyme has maximum turn over number (i.e. 36 million). Minimum turn over number for an enzyme:

(A)  DNA polymerase

(B)   Lysozyme

(C)   Penicillase

(D)  Lactase dehydrogenase

3)    Hemolytic anemia is caused by the deficiency of a specific enzymes of the pentose phosphate pathway, the principal enzyme involved is

(A)  Glucose-6-phosphate dehydrogenase

(B)   Aldolase

(C)   Fructose 1, 6-bisphosphatase

(D)  Phosphohexose isomerase

4)    Which of the following is a microsomal enzyme inducer?

(A)  Indomethacin

(B)   Clofibrate

(C)   Glutethamide

(D)  Tolbutamide

5)    Dry seeds survive on higher temperature than germinating seeds as

(A)  Hydration is essential for making enzymes sensitive to temperature

(B)   Dry seeds have a hard covering

(C)   Dry seeds have more reserve food

(D)  Seedlings are tender

6)    Covalent modification of an enzyme usually involves phosphorylation/ dephosphorylation of

(A)  Serine residue

(B)   Proline residue

(C)   Hydroxylysine residue

(D)  Hydroxyproline residue

7)    Which of the following enzyme typically elevated in alcoholism?

(A)  Serum ALP

(B)   Serum GOT

(C)   Serum g-GT

(D)  None

8)    The glycogen content of the liver is upto

(A)  6% (B) 8%

(B)   10% (D) 12%

9)    Acute hemolytic episode after administration of antimalarial, primaquin, is due to deficiency of the enzyme:

(A)  6-Phosphogluconate dehydrogenase

(B)   Glucose-6-phosphate dehydrogenase

(C)   Epimerase

(D)  Transketolase

    10)  Which of the following is known as bone forming enzyme?

(E)   Alkaline phosphatase

(F)    Acid phosphatase

(G)  Leucine aminopeptidase

(H)  none

Answers 1-C, 2-B, 3-A, 4-C, 5-A, 6-A, 7-C, 8-B, 9-B, 10-A