Respiratory RNA viruses are continuing to challenge man with epidemics and devastating pandemics. These findings suggest that combination of trimethoprim and zinc at optimal ratio can be provided as treatment for influenza and possibly other respiratory RNA viruses infection in man. ConclusionĪcting on host cells, Tri-Z at optimal ratio can reduce the lethal effect of influenza A virus in chick embryo. However, at clinical concentration of 5 µg/ml, Tri-Z had partial HAI effect (+ +). At concentration of 15 µg/ml of optimal ratio, Tri-Z had total HAI effect (scored 0).

Tri-Z, at ratio range of 0.15–0.2 (optimal ratio of 0.18) Zn/TMP, enabled embryos to survive influenza virus despite increasing viral load (> 80% survival at optimal ratio). All embryos treated with convalescent serum survived. TMP, Zn or saline separately had no effect on embryo survival, none of the embryos survived influenza virus infection. HAI effect was expressed as scores where ++++ = no effect 0 = complete HAI effect. Tri-Z was prepared to concentration of 10 mg TMP and 1.8 mg Zn per ml, then serial dilutions were made. The effect of Tri-Z on virus binding to its cell surface receptor was evaluated in a hemagglutination inhibition (HAI) assay using chicken red cells. Controls of Zn, TMP, saline or convalescent serum were conducted in parallel. Embryo survival was determined by candling eggs daily for 7 days. A mixture of zinc oxide (Zn) and trimethoprim (TMP) (weight/weight ratios ranged from 0.01 to 0.3, Zn/TMP with increment of 0.1) was tested for embryo survival of the infection (n = 12 per ratio, in triplicates). We introduced 10 ELD 50 into embryonated eggs and repeated the experiments using 100 ELD 50. We determined viral load that infects 50% of eggs (50% egg lethal dose, ELD 50).

Influenza virus was isolated from patients and propagated in eggs. We examined whether a combination of trimethoprim and zinc (Tri-Z), that acts on the host, can reduce the lethal effect of influenza A virus in chick embryo model. Influenza virus infection is lethal to the chick embryo. These viruses depend on its host for replication and infection. Respiratory RNA viruses including influenza virus have been a cause of health and economic hardships.

96 Hour Chick Embryo Serial Section