In 1989, 54 nucleotides from chicken 18s were seen to be inserted into the haemagglutinin gene of an influenza virus increasing viral pathogenicity [1]. Previously, I have reported human 18s sequences (from sequence vectors) appended to the influenza virus genome in Covid19 patients from Wuhan and Hong Kong [2]. These human ribosomal sequences are supposed to increase the transcription of the virus in the human cell, and thus will be more pathogenic. Here, I report the circulation of Influenza A genomes with 28s from canine integrated, showing that the escape of lab-made viruses is quite prevalent.Canine 28s sequence appended to flu genomesA recent (2020,Accid:PRJNA605947) study from the University of Hong Kong that did Nanopore sequencing to find novel targets for detection and surveillance of Influenza A viruses [3] shows the integration of canine 28s (Fig 1) sequence to the flu genome. The full read (SRR11067307.3179,SI:fullread.fa) splits into the flu virus (1-1605, SI:flu.baltimore.fa,(Baltimore/R0197/2017(H1N1)) nucleocapsid protein (NP) gene) and canine 28 (1606-1973, SI:canine.28s.fa Accid:XR 004817748.1, Canis lupus dingo 28S)). There is no reason to find canine 28s in clinical samples, barring the fact that canine kidney cells are used to manufacture the virus for several applications, including vaccines.Madin Darby canine kidney cells (MDCK) - why MDCK?The advantages of using MDCK influenza production is well known [4]. MDCK is better in the replication of live attenuated influenza viruses than most other cell lines (like Vero), thus yielding more virus in large-scale production of influenza virus [5]. The virus replicates rapidly in MDCK to ‘produce high titers in MDCK cells in as few as 3 to 10 passages, i.e., in 10–30 days’ [4]. Also, MDCK cells are also good for the production of certain influenza B virus vaccines, and MDCK cell-derived components are not allergenic [6]. Vaccines made using MDCK cellsInfluvac, a split virus vaccine produced in adherent MDCK cells, in the Netherlands in 1999 [7]. The use of MDCK cells (MedImmune) for production of live attenuated influenza vaccine in both serum containing and serum-free media was found to be more efficient [8]. Another trivalent MDCK cell culture-derived influenza vaccine is Optaflu [9]. ”Flucelvax Quadrivalent is the only cell-based inactivated flu vaccine that has been licensed by the FDA for use in the United States.” (https://www.cdc.gov/flu/prevent/cell-based.htm)
High yields of influenza A virus in Madin-Darby canine kidney cells are promoted by an insufficient interferon-induced antiviral state
