Arboviruses and Picorna Viruses MCQs

Salk (Injectable Polio Vaccine) is prepared by Formalin killed strain. No local & herd immunity Zero chance of VAPP & VDPV Can be given to immunocompromised patient, pregnant and old aged patients Short duration of protection Relatively safer than OPV Sabin (Oral Polio Vaccine) is prepared from live attenuated strain. Provides both local & herd immunity More chances of VAPP & VDPV Cannot be given to immunocompromised patient, pregnant and old aged patients Longer duration of protection Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, Page Number 711

Yellow fever is an acute febrile illness which is characterized by liver dysfunction which leads to jaundice. Humans get the infection by the bite of Aedes aegypti or tiger mosquito. Reference : Ananthnarayan and Paniker's textbook of Microbiology 12 th edition pg no.530

Vaccine-associated paralytic poliomyelitis (VAPP) is due to an OPV-like isolated strain, which is slightly genetically divergent from parental OPV strain. VAPP is spread among recipient and its close contacts, and it cannot cause an outbreak. Vaccine-derived polioviruses (VDPVs) show high level of genetic divergence from parental OPV strain at VP1 sequences. Most VDPV cases occur due to IPV type 2 strain. VDPVs can be classified into 3 types: Circulating VDPVs Immunodeficiency-associated VDPVs Ambiguous VDPVs Reference: https://www.sciencedirect.com/science/article/abs/pii/S0264410X98004095

Picornaviruses are +ve sense ssRNA, non-enveloped and icosahedral in shape. Picornaviruses are classified into 2 main groups: Enteroviruses: transmitted by feco-oral route Poliovirus Coxsackie virus Echovirus Parechovirus Hep A virus Rhinovirus: transmitted by respiratory route and cause common cold Enteroviruses are the most common viruses that can cause meningo-encephalitis in children. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, Page Number 82

Viral interference is when two viruses infect a host line or a cell line and one of the viruses leads to an inhibition of the other. Genetic reassortment is seen in segmented viruses, such as influenza. Genetic recombination occurs between related viruses of the same family infecting a host cell simultaneously. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd Edition, Page Number 86

Poliovirus may be detected from throat swabs (upto 1 week of illness) or from stool samples (upto 6-8 weeks of illness). However, longer excretion rates are observed in case of immunocompromised patients. Virus isolation from CSF or blood is very rare. Reverse cold chain (RCC) technique is used to transport stool samples from site of collection to laboratory. Other Options: d. Slit skin smear is used to detect M. leprae (Leprosy) Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, Page Number 711

Poliovirus is transmitted by feco-oral route. It multiplies locally in Peyer's patches in the intestines, tonsils and other lymphoid tissue. Entry into the host cell is via CD155 receptor. Spread to spinal cord is via hematogenous route or neural route. Final site of action is the Anterior Horn Cell of the spinal cord which leads to muscle weakness and flaccid paralysis. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, Page Number 710

RNA viruses which have segmented RNA are: Arenavirus: 2 segments Bunyavirus: 3 segments Orthomyxovirus: 8 segments Reovirus: 10-11 segments Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd Edition, Page Number 80