Quantification of the Influenza Virus Load by Real‐Time Polymerase Chain Reaction in Nasopharyngeal Swabs of Patients Treated with Oseltamivir

Abstract

Influenza A virus load was assessed by real-time polymerase chain reaction (PCR) in nasopharyngeal swabs of infected patients treated with oseltamivir. The mean pretreatment virus load was significantly lower in the 24 patients (group A) who initiated treatment within 24 h of the onset of symptoms than it was in the 26 patients (group B) who initiated treatment between 24 and 48 h (1.6x105 vs. 8.4x105 copies/600 ng of total RNA, P=.04); after 48 h of treatment, twice as many patients in group B still had a positive PCR result, compared with patients in group A (42.3% vs. 20.7%). These virological results support the clinical benefit provided by early therapeutic intervention of influenza illness.

Incorporation of a Proteotyping Approach Using Mass Spectrometry for Surveillance of Influenza Virus in Cell-Cultured Strains

“…2 to 6. Based upon the reported mass of an influenza virus particle of 5 femtograms or 5 ϫ 10 Ϫ16 g (21), this corresponds to ϳ10 5 copies of the virus, a value comparable to that reported for the RT-PCR analysis of virus obtained from nasopharyngeal swabs (22).…”

Should vaccines and antiviral therapy for influenza now be deployed strategically?

“…The results of a multi-centre international study have recently confirmed the expectation that early treatment with oseltamivir significantly reduces the total duration of illness more effectively than does delayed treatment [13]. This is consistent with studies showing more rapid control of influenza viral load in patients given oseltamivir within the first 24 hours of illness onset [14]. Since these drugs effectively suppress viral replication, they should not, of course, be given to individuals who have recently received live attenuated vaccine, further illustrating the need for a two stage vaccine/drugs approach to controlling influenza.…”

Influenza virus shedding—Excretion patterns and effects of antiviral treatment

“…Moreover, negative PCR results were achieved more rapidly if the treatment was initiated within the first 24 h (n = 24) of onset of symptoms than after 24 h of symptom onset (n = 26). 37 In contrast to these studies, in a placebo-controlled trial in 629 adults, treatment with oseltamivir 75 mg or 150 mg BID had no significant effect on virus shedding and titers (Table 3) in naturally acquired influenza A infections. 33 There are limited data on the effects of treatment with zanamivir on viral shedding.…”