final program.qxd - Parallels Plesk Panel

PP 6.5
Experimental determination of the infectivity of avian influenza virus aerosols
A.S. Safatov, A.N. Sergeev, S.A. Kiselev, E.A. Stavskij, L.N. Shishkina, E.I. Ryabchikova,
M.O. Skarnovich, A.A. Sergeev, M.A. Smetannikova, A.P. Agafonov, V.A. Petrishchenko,
V.M Generalov, G.A. Buryak, I.G. Drozdov
Federal State Research Institution State Research Center of Virology and Biotechnology
"Vector", Koltsovo, Novosibirsk region, Russia.
According to the WHO data, 212 human cases of H5N1 avian influenza (including 116
lethal ones) have been reported since 1997 in different countries by the beginning of April
2006. Human diseases occur through the contact with infected birds while
human-to-human transmission of the virus has not been recorded. As the aerosol way of
human-to-human transmission of influenza is the main one, we investigated aerosol
characteristics of avian influenza virus ?/Chicken/Suzdalka/Nov-11/2005 (?5N1) isolated
in Novosibirsk region and its infectivity for chickens.
At the first stage, the comparison of survival rates of avian influenza virus and human
influenza virus (A/Aichi/2/68 strain ?3N2 subtype) was performed via aerosolizing an
aqueous-glycerol solution of virus-containing suspensions using a Collison nebulizer.
It was found out that 3.6 ± 1.8% of virions preserved their infectivity in the dispersion of
human influenza virus at the temperature of 21÷23?? and the relative humidity of
approximately 30%. For avian influenza virus, this quantity makes up only 1.0 ± 0.9%
under the same conditions. Electron microscopic analysis of the virions morphology
performed with the negative contrasting method revealed the "staining" of the core of
avian influenza virion as compared with human influenza virions, which is indicative of the
destruction of membranes. Peplomers, usually existing on the surface of human
influenza virions, were not found either.
To determine the chickens' sensitivity to the studied strain of avian influenza virus, the
birds were challenged intravenously or intranasally. Intranasal infection is equivalent to
that with a coarsely dispersed aerosol, but allows the infecting dose to be controlled more
precisely. It was found out that, on average, the dose of 1 EID50 caused 50% death rate
at intravenous infection of birds. This indicates that LD50 values coincide both for an ECE
and an adult bird. At intranasal infection of chickens, LD50 value is estimated at 500 -
1000 EID50. Thus, infection of birds with a coarsely dispersed aerosol of avian influenza
virus is not the most efficient way of the infection transmission as it happens in the
process of human-to-human transmission of human influenza virus.
The carried out experiments showed that, obviously, the aerosol way of the infection
transmission is not the main one at bird-to-bird and bird-to-human transmission of avian
influenza. The analysis of literature sources show that for birds the main way of the virus
transmission is fecal-oral, and for man it is, probably, an analogue of the former as a result
of nonobservance of the personal hygiene rules.
“ Focusing FIRST on PEOPLE “ 222 w w w . i s h e i d . c o m