# 4312
The study which was conducted in Hong Kong and which appears in The American Journal of Pathology is entitled:
Michael C.W. Chan*@, Renee W.Y. Chan*, Wendy C.L. Yu*, Carol C.C. Ho*, Kit M. Yuen*, Joanne H.M. Fong*, Lynsia L.S. Tang*, Wico W. Lai, Amy C.Y. Lo, W. H. Chui, Alan D.L. Sihoe, Dora L.W. Kwong¶, David S.H. Wong, George S.W. Tsao, Leo L.M. Poon*, Yi Guan*, John M. Nicholls, and Joseph S.M. Peiris**@
A mouthful to be sure, but one of the major findings is that the novel H1N1 virus – unlike seasonal flu – easily infects and replicates in the conjunctival tissues of the eye.
You’ll probably also note some well known names among the authors of this study, including Guan Yi and Malik Peiris.
Conjunctivitis is sometimes associated with mild avian flu infections in humans, and in tests conducted on baby piglets in Thailand last May (see Casting Viruses Before Swine), conjunctivitis was one of the commonly observed symptoms with the novel H1N1 virus.
Anecdotal accounts have come in as well associating conjunctivitis and the novel H1N1 virus. Indigo Girl on the allnurses pandemic forum started a thread on that very subject in late July of last year.
But today’s study is the first I’ve seen that directly addresses the virus’s ability to infect a host through the membranes of the eye.
This study also seems to indicate that – unlike the highly virulent H5N1 virus – novel H1N1 is no more likely to produce a cytokine disruption than is seasonal influenza.
First the abstract from the Journal Article, then a Hong Kong newspaper story on the findings.
The novel pandemic influenza H1N1 (H1N1pdm) virus of swine origin causes mild disease but occasionally leads to acute respiratory distress syndrome and death. It is important to understand the pathogenesis of this new disease in humans.
We compared the virus tropism and host-responses elicited by pandemic H1N1pdm and seasonal H1N1 influenza viruses in ex vivo cultures of human conjunctiva, nasopharynx, bronchus, and lung, as well as in vitro cultures of human nasopharyngeal, bronchial, and alveolar epithelial cells.
We found comparable replication and host-responses in seasonal and pandemic H1N1 viruses. However, pandemic H1N1pdm virus differs from seasonal H1N1 influenza virus in its ability to replicate in human conjunctiva, suggesting subtle differences in its receptor-binding profile and highlighting the potential role of the conjunctiva as an additional route of infection with H1N1pdm.
A greater viral replication competence in bronchial epithelium at 33°C may also contribute to the slight increase in virulence of the pandemic influenza virus. In contrast with highly pathogenic influenza H5N1 virus, pandemic H1N1pdm does not differ from seasonal influenza virus in its intrinsic capacity for cytokine dysregulation.
Collectively, these results suggest that pandemic H1N1pdm virus differs in modest but subtle ways from seasonal H1N1 virus in its intrinsic virulence for humans, which is in accord with the epidemiology of the pandemic to date. These findings are therefore relevant for understanding transmission and therapy.
The following is an excerpt from a Hong Kong Standard story on this research. Follow the link to read it in its entirety.
MaryAnnBenitez
Tuesday, February 02, 2010
New research has revealed that the swine flu virus can be spread through the eyes, underscoring the importance of personal hygiene to avoid the disease.
University of Hong Kong researchers compared the ability of swine flu H1N1 and the seasonal H1N1 and H3N2 flu viruses to replicate in cells and tissue samples from the human upper and lower respiratory tract and in the cells lining the surface of the eye.
It found that swine flu is more efficient than seasonal flu in infecting the eyes.
The study by the HKU departments of microbiology and pathology was published in the American Journal of Pathology.
"We found that pandemic H1N1 flu can actually infect and replicate in conjunctiva [the eyes] while the seasonal flu cannot," said Michael Chan Chi-wai, research assistant professor of the department of microbiology.
"The public should be made more aware to wash their hands before rubbing their eyes. It is an important route for pandemic flu."
The research also found that unlike bird flu H5N1, swine flu did not lead to a hyper-activation of the human cell cytokine response, a mechanism believed to contribute to the severity of bird flu H5N1 infection.
