Question

In an experiment, the common Tobacco Mosaic Virus (TMV) and its mutant strain ‘HR’ were used to prepare hybrid particles with ‘HR’ nucleic acid and ‘TMV’ protein coat. These hybrids were mixed with antibodies against ‘HR’ strains. If this mixture is applied to plant materials, it will result in
A. Loss of infectivity of virus particles due to inactivation of nucleic acid
B. Loss of infectivity due to inactivation of the protein coat
C. Intact infectivity because the only coat is neutralized
D. Unchanged infectivity because neither nucleic add nor protein coat is neutralized

Answer 1

Hint: The TMV is a single-stranded positive-sense RNA virus species belonging to the Tobamovirus genus that infects a wide variety of plants. They infect especially tobacco and other members of the Solanaceae family. Relevant nucleotide variations in the tobacco mosaic virus (TMV) coat protein gene have been reported as being responsible for inducing the hypersensitive reaction (HR).

Complete answer: In the given experiment, TMV and its mutant strain 'HR' were used for the preparation of hybrid viral particles with the nucleic acid; HR strain and Protein coat; TMV. We know that when a viral particle infects another host, it transmits its genetic material, that is, nucleic acid, into the host. If the mixture of hybrid viral particles and HR strain antibodies are mixed together, the HR strain antibodies can neutralize the effect of the nucleic acid of the HR strain, resulting in the loss of infectivity of virus particles due to the inactivation of the nucleic acid. Techniques were first developed to distinguish TMV particles into RNA and proteins. Later, by using RNA and proteins separately in infection experiments, it could be shown that RNA alone can cause infection. Chimeric virus particles can also be synthesized using RNA from one strand and protein from another strand.
Therefore, option A is the correct answer.

Note: The first virus to be discovered was TMV. Experiments performed with the tobacco mosaic virus presented the first confirmation that RNA also has the ability to bear genetic material (TMV). The infection triggers characteristic patterns such as mosaic, such as mottling and discolouration on the leaves.