4,7-dialkoxy N-acetylneuraminic acid derivatives and methods for detection of influenza type A and B viruses in clinical specimens

A method for detecting influenza type A and B viruses in a clinical sample from an individual suspected of having a respiratory viral infection, said method comprising:

• (1) incubating the clinical sample with a chromogenic or fluorogenic 4,7-dialkoxy N-acetylneuraminic acid substrate of the general formula:
• ##STR17## wherein R.sub.1 and R.sub.2 are alkyl radicals containing 1 to 4 carbon atoms and R.sub.3 is a chromogenic or fluorogenic group that exhibits a distinct and characteristic color when cleaved from the substrate or a salt of the substrate;
• (2) concentrating any precipitate formed in the incubated clinical sample;
• (3) observing the concentrated precipitate to determine whether the distinct and characteristic color is formed, wherein the formation of the distinct and characteristic color indicates the presence of influenza type A or B viruses in the clinical sample.

A method for detecting influenza type A and B viruses in a clinical sample from an individual suspected of having a respiratory viral infection, said method comprising:

• (1) dividing the clinical sample into a first portion and a second portion;
• (2) incubating the first portion with a chromogenic or fluorogenic 4,7-dialkoxy N-acetylneuraminic acid first substrate of the general formula:
• ##STR18## wherein R.sub.1 and R.sub.2 are alkyl radicals containing 1 to 4 carbon atoms and R.sub.3 is a first chromogenic or fluorogenic group that exhibits a distinct and characteristic first color when cleaved from the first substrate or a salt of the first substrate;
• (3) concentrating any precipitate formed in the incubated first portion;
• (4) observing the precipitate formed in the incubated first portion to determine whether the distinct and characteristic first color is formed, wherein the formation of the distinct and characteristic first color indicates the presence of influenza type A or B viruses in the clinical sample;
• (5) incubating the second portion with a chromogenic or fluorogenic 4-alkoxy N-acetylneuraminic acid second substrate of the general formula:
• ##STR19## wherein R.sub.4 is an alkyl radical containing 1 to 4 carbon atoms and R.sub.5 is a second chromogenic or fluorogenic group that exhibits a distinct and characteristic second color when cleaved from the second substrate or a salt of the second substrate;
• (6) concentrating any precipitate formed in the incubated second portion;
• and
• (7) observing the precipitate formed in the incubated second portion to determine whether the distinct and characteristic second color is formed, wherein the formation of the distinct and characteristic second color indicates the presence of neuraminidase reactive viruses in the clinical sample;
• wherein the presence of the first and second colors indicates the presence of influenza type A or B viruses alone or in combination with neuraminidase reactive viruses other than influenza type A and B viruses in the clinical sample;
• wherein the presence of the second color and the absence of the first color indicates neuraminidase reactive viruses other than influenza type A and B viruses in the clinical sample;
• and
• wherein the absence of the first and second colors indicates the absence of neuraminidase reactive viruses in the clinical sample.