This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Antigenic variation is/are seen in- \nSelect and explain. \nA. Treponema pallidum, B. Neisseria, C. Corynebacterium, D. All', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is \'b\' i.e., Neisseria Antigenic variation It is the process by which an infectious oganism alters its surface proteins in order to evade a host immune response. . Antigenic variation not only enables immune evasion but also allows pathogens to cause reinfection as they are not recognised by the host\'s immune response . . Antigenic variation enables viruses to cross the species barrier,(eg. H5Nlvirus "jumping" from birds to then infect humans). . Antigenic variation in bacteria is best demonstrate by: species of the genus Neisseria ( most notably, Neisseria meningitidis and Neisseria gonorrhoeae, the gonococcus);Borrelia recurrentis; species of the genus Streptococcus and the Mycoplasma. . Antigenic variation in viruses is best demonstrated by : by HIV ( Human Immunodeficiency Virus); Influenza virus and Hepatitis virus, rhinoviruses and enteroviruses. . Antigenic variation in protozoa is best demonstrated by : species of the genus Plasmodium ( responsible for causing malaria) and the trypanosomes ( Trypanosoma cruzi which causes Chagas disease and T. bruzi gambiense and T. bruzi rhodesiense which both cause African sleeping sickness).', 'role': 'assistant'}]