Coinfection by segmented viruses such as influenza can result in the exchange of segments from different serotypes to produce new serotypes (H1N2 & H2N1). This process is termed reassortment.
Reassortment refers to the exchange of segmented genomes of different viral serotypes and/or recombination of genes on different segments. This is common in influenza, whose segmented genome is composed of 8 different segments. Hemagglutinin and neuraminidase are located on different segments; therefore, when two different serotypes coinfect a cell, there exists the possibilty of reassortment and the creation of a new serotype.
Urbaniak and Markowska-Daniel review the reassortment of influenza viruses, which are composed of 8 (-) ssRNA segments. Reassortment is an evolutionary mechanism that allows for a virus to infect a wider range of hosts. Reassortment was the cause of the following pandemics: Asian flu (1957), Hong Kong flu (1968), and the swine flu (2009), which contained viral segments from avian, swine, and human influenza viruses.
Wang et al. discuss the appearance of a new, reassorted influenza virus, H7N9, in several provinces and municipalities in China. The virus is composed of segments from H9N2, H7N3, and H11N9 (an avian virus) and demonstrates the possibility that avian viruses may cross species.
Illustration A shows a pictorial representation (provided by the NIAID) of the process of reassortment during vaccine production. Video V describes antigenic shift, direct transfer, and reassortment.
Answer 1: Recombination refers to the exchange of genes between homologous regions on two different chromosomes.
Answer 3: Complementation refers to the coinfection of two viruses. One virus is defective and unable to produce progeny on its own, and the other contains genes for proteins that assist the defective virus in producing viable progeny.
Answer 4: Phenotypic mixing refers to the coinfection of two viruses where one viral genome is coated by the viral coat of another. This results in the formation of a pseudovirion where the nucleic acid and coat are completely mismatched.
Answer 5: Transformation is a bacterial term that refers to the uptake of naked DNA by the bacteria from the environment.
Urbaniak K, Markowska-Daniel I. In vivo reassortment of influenza viruses. Acta Biochim Pol. 2014 Sep 3.
PMID:25180223 (Link to Abstract)
Wang C, Luo J, Wang J, Su W, Gao S, Zhang M, Xie L, Ding H, Liu S, Liu X, Chen Y, Jia Y, He H. Novel human H7N9 influenza virus in China. Integr Zool. 2014 Jun;9(3):372-5. doi: 10.1111/1749-4877.12047.
PMID:24952971 (Link to Abstract)