Question

synergism

Page 2 of 5 Rabibove love 18. The Spectrum of cells a virus can infect is defined as the host mange. Which of the following viral pathogens has the widest host range? & Hepatitis B adsorbs to human liver calls & Poliovirus attaches to intestinal and nerve cells c Rabies attaches to several cells of many mammals a all the above C none of the above 19. In Persistent infections, the cell harbors the virus, which is not immediately lysed. This condition can last for weeks or the host's Hetimes several viruses are known to periodically reactivate and multiply. persistent infections include: & Measles vins which may remain hidden in brain cells for many years & Herpes simplex virus, which causes cold sores and genital herpes 5 Herpes zoster virus, which causes chickenpox and shingles @ all the above none of the above 20. Not all bacteriophages complete the lytic gyde. Some DNA phages (called temperate phages) undergo adsorption and penetration but don't replicate. Instead, the viral genome inerts itself into bacterial genome (DNA) and becomes an inactive prophage - the cell is not lysed. The Prophage is retained and copied during normal cell division resulting in the transfer of temperate phage genome to all host cell progeny. Thi process is paliaty adsorption alternate pathway d lysogeny e transformation 21. The cause of transmissible spongiform encephalopathies (they are fatal neurodegenerative diseases). Examples are, Scrapie in sheep and goals; Bovine spongiformi encephalopathics (mad cow disease), and Creutzfeldt-Jakob Syndrome and & they contain RNVA k they contain viroids c all the above e none of the above 22 Nuclenses are enzymes that cleave (break) chemical bonds in DNA & RNA. Nuclenses do not damage: prons a animal viruses c roids a bacteriophage e infuenza virus

Answer 1

18)Option c is the right answer.

A variety of mammals, including dog, fox, wolf, jackal, raccoon, skunk, mongoose, and numerous species of bats, can serve as reservoir hosts of rabies virus that then transmit the virus to other mammals.

In option a and b hepatitis B and poliovirus respectively they affect humans.

19) Option d is the correct answer.

Measles virus infection is a highly contageous disease.Recent studied have shown that it can remain in brain cells for many years and can cause serious cosequences.Herpes simplex virus which causs cold sores and genital herpes and herpes zoster virus which cause chicken pox and shingles are also persistent infections.After chicken pox infection the virus remains in nervous tisuues and it become activated and can cause shingles in adult life.Genital herpes is a sexually transmitted disease and it can not be eliminated completely by treatment.

20)Option d lysogeny is the correct answer.

In lysogenic cycle Temperate phages (prophage) become associate with host genome.Bacteria harbouring virus is called lysogenic bacteria.Phage DNA replicates along with bacterial genome.UV radiation and presence of hydrogen peroxide covert prophage into virulent phage and process is called induction.

Specificity means virus can infect only certain cells of a particular species.

Adsorption is the first stage in virus multiplication.

Alternate pathway is a complement pathway.

Transformation is associated with bacteria.

21)Option d is the correct answer.Prions are proteinaceous infectious particles and causes a uniformly fatal neurological disease in both humans and animals characteristics by Spongiform or Vaccoulating lesions in the grey matter of brain and neuronal perikarya. Disease in humans are described as CJD (Creutzfelt Jacob Syndrome), GSS (Gerstmann Straussler Scheinker Syndrome), FFI (Fatal Familial Insomnia) and KURU disease and in animals they causes. Scrapie in sheep and goats and in cattle BSE (Bovine spongiform Enu. or Mad Cow Disease and in minks, TME (Transmissible Mink Encephalopathy) CWD in deer and Elk (chronic wasting disease).

22)Option a is the correct answer.Prions are proteins.They are not cleaved by nucleases.Other options are viruses(contain either DNA or RNA) and viroid (contain free RNA).