Avian-Human Reassortant Influenza A Viruses Derived by Mating Avian and Human Influenza A Viruses

Abstract

Reassortant influenza A viruses were produced by mating an avian virus (A/Mallard/NY/78, A/Mallard/Alberta/78, or A/Pintail/Alberta/79) with a wild-type human influenza A virus. From each mating a reassortant virus was obtained that contained the genes coding for the hemagglutinin and neuraminidase surface antigens of the human influenza A wild-type virus and the six other RNA segments ("internal genes") of the avian influenza A virus parent. The avian-human reassortant influenza viruses produced resembled their avian virus parent in that they produced plaques on MDCK monolayers at 42 C, a temperature restrictive for the human influenza viruses. In the trachea of squirrel monkeys, each avian-human reassortant influenza virus was as restricted in its replication as was its avian influenza virus parent. Thus, one or more of the six internal genes of each avian parent virus was responsible for restriction of the reassortant virus in monkeys. The A/Washington/80 X A/Mallard/NY/78 reassortant virus retained its phenotype of restricted replication in monkeys after five serial passages in vivo. It also failed to transmit to cagemates or induce resistance to wild-type virus challenge, and it did not initiate a systemic or enteric infection. These findings form the basis for evaluation of these attenuated avian-human reassortant influenza A viruses as live attenuated vaccines for humans.

Circulating Avian Influenza Viruses Closely Related to the 1918 Virus Have Pandemic Potential

“…Generally, in experimental infections, avian influenza viruses replicate poorly in humans and vice versa (Beare and Webster, 1991; Hinshaw et al, 1984; Murphy et al, 1984; Webster et al, 1978) because host restriction constrains interspecies transmission. Recently, however, a newly emerged H7N9 avian influenza virus appeared to break this host barrier and directly infect humans in China, resulting in a total of 238 confirmed cases and 57 fatalities as of 26 Jan 2014 (unofficial statement; http://www.cidrap.umn.edu/news-perspective/2014/01/eleven-new-h7n9-cases-include-one-beijing).…”

Regulatory effects of matrix protein variations on influenza virus growth

“…Early in vivo studies indicated that the M gene plays roles in the growth control of influenza virus in embryonated eggs and squirrel monkeys [2,22,30], and in the neurotropism in mouse brain [24]. The M gene of influenza viruses encodes 2 proteins, M 1 and M2 [17,20].…”

“…The origin of RNA segments of each reassortant virus was determined by measuring RNA size by polyacrylamide gel electrophoresis (PAGE) [22]. Viral RNA was extracted from purified virions with phenol :chloroform (1 : 1) and precipitated with ethanol.…”

New Methodological Approaches in The Development of Russian Live Attenuated Vaccine for Pandemic Influenza

“…Co-infection step plays a key role in the classical genetic reassortment. Multiple studies have attempted to evaluate reassortment efficiencies of wild-type and cold-adapted viruses using different variants of crossing procedures, such as simultaneous [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] or successive [27][28][29] inoculation of two parental viruses. Co-infection procedures also differed by infectivity ratio of the viruses, temperature of incubation and culturing substrate (eggs or cell culture).…”

“…Co-infection procedures also differed by infectivity ratio of the viruses, temperature of incubation and culturing substrate (eggs or cell culture). Most of the recent studies describe reassortment of live parental viruses [11][12][13][14][15]20,[22][23][24][25][26]. However, the reassortment efficiency can be substantially improved if one of the parental viruses is inactivated prior to co-infection.…”