Cell-based influenza vaccine: current production, halal status assessment, and recommendations towards Islamic-compliant manufacturing

Figures & data

Figure 1. Generic production process of a cell-based influenza vaccine. 1) The upstream process involves replication of host cells grown in a bioreactor containing formulated growth media. Sufficient host cells are then inoculated with influenza virus with trypsin addition to assist internalization of the virus into the host cells. 2) After a few days of incubation, the culture solution containing influenza virus undergoes separation and purification processes using various types of centrifuge and filtration units. 3) Subsequently, the purified virus is exposed to formaldehyde to inactivate its virulence. 4) The aseptically filtered inactivated influenza virus is later formulated with excipients before being packaged as a powdered or liquid influenza vaccine

Table 1. Opinion of Islam on various types of host cells used for influenza virus propagation

Host Cell	Origin	Source	Opinion of Islam ^a
MDCK	Dog	Kidney ^b	Categorized as a carnivorous animal with fangs and claws, thus, haram to be consumed.
Vero	Monkey	Kidney ^b	Categorized as a wild animal with fangs and claws, thus, haram to be consumed
BHK-21	Hamster	Kidney ^b	Categorized as a dirty and disgusting animal, thus haram to be consumed
Sf9	Insect (fall armyworm)	Ovarian cell ^c	Categorized as a dirty and disgusting animal, thus haram to be consumed
HEK 293	Human	Embryonic kidney or neuronal cell ^b	Human is a pure creature that must be respected, thus haram to be consumed
PER.C6	Human	Embryonic retinoblasts ^b	Human is a pure creature that must be respected, thus haram to be consumed
EB66	Duck	Embryonic stem cell ^b	Categorized as a bird without fangs and claws, which is halal to be consumed only if slaughtered with the name of Allah. Otherwise, will be considered as carcasses which are haram to be consumed
AGE1.CR	Duck	Embryonic retina ^b	Categorized as a bird without fangs and claws, which is halal to be consumed only if slaughtered with the name of Allah. Otherwise, will be considered as carcasses, which are haram to be consumed
DuckCelt-T17	Duck	Embryo ^d	Categorized as a bird without fangs and claws, which is halal to be consumed only if slaughtered with the name of Allah. Otherwise, will be considered as carcasses, which are haram to be consumed
PBS-1	Chick	Embryo ^b	Categorized as a bird without fangs and claws, which are halal to be consumed only if slaughtered with the name of Allah. Otherwise, will be considered as carcasses, which are haram to be consumed

^aBased on sharia laws as stated in Standards Malaysia.⁷

^bInformation extracted from Genzel.⁴¹

^cInformation extracted from Cox and Anderson.⁴⁶

^dInformation extracted from Petiot et al.⁴⁴

Table 2. Components of growth media and their corresponding opinion of Islam

Category	Example ^a	Opinion of Islam ^b
Human-derived product	Insulin, transferrin, albumin, xeno-free media, etc.	Haram for consumption as human parts/derivatives are pure materials that must be respected and not being exploited or commercialized.
Animal-derived product	Amino acid, lipid (cholesterol, steroid, fatty acid), growth factor, hydrolyzate (animal tissues, milk), hormones, carrier protein, etc.	Halal if sourced from halal and religiously slaughtered animals (chick, bovine, fish) Haram if sourced from non-halal animals (e.g., porcine, wild animals, amphibians) or non-slaughtered animals (e.g., bovine)
Plant-derived product	Hydrolyzate (soy, wheat, rice), glucose, maltose, vitamins, lipid, etc.	All plant-based products except those from poisonous, intoxicant, or hazardous plants are halal to be consumed.
Blood-derived product	Serum, plasma, platelet-derived product, albumin, etc.	Haram as blood is considered as filth material which stringently forbidden for any consumption.
Chemical synthesis product	Inorganic salts (CuSO4, KCl CaCl2,), trace elements, selenite, sodium bicarbonate, etc.	All chemical-based or chemical synthesized products except poisonous, intoxicant, or hazardous chemicals are halal to be consumed.
Fermentation/Microbial product	Amino acid, vitamins, yeast hydrolyzate, glutathione, etc.	Halal if the materials (e.g., growth media) and microbes used in the fermentation are sourced from halal resources.
Recombinant product	Insulin, transferrin, etc.	Recombinant products expressed using genetic materials (e.g., plasmid, DNA, RNA) originated from halal and slaughtered animals or microorganism are considered as halal. Otherwise, will be considered as najs which are haram for consumption.

^aThe examples were extracted from Yao and Asayama.⁴⁹

^bBased on sharia laws as stated in Standards Malaysia.⁷

Table 3. Opinion of Islam on different types of commercialized proteolytic enzymes

Proteolytic Enzyme	Origin	Opinion of Islam ^a
Trypsin	Porcine ^b	Haram to be consumed
Trypsin	Bovine ^c	Halal to be consumed if extracted from bovine slaughtered with the name of Allah. Otherwise, considered as part of carcasses, thus, haram to be consumed.
TrypLE	Recombinant fungi ^d	Halal to be consumed if genetic materials used are originated from halal sources. Natural microorganisms, including fungi itself, are halal according to sharia laws unless prohibited by the competent authority.
Accutase	Marine life (crustacean) ^d	Halal to be consumed unless extracted from amphibians, disgusting, poisoning, and intoxicating organisms.

^aBased on sharia laws as stated in Standards Malaysia.⁷

^bInformation extracted from Khoo et al.⁴

^cInformation extracted from Mótyán, Tóth, and Tőzsér.⁶⁵

^dInformation extracted from Rourou et al.⁶⁷

Table 4. Impermissible materials used in current production of cell-based influenza vaccines and their corresponding sharia-compliant alternatives

Types of materials	Impermissible materials	Alternative materials
Host cell	MDCK cell line	Duck (EB66, AGE1.CR, DuckCelt-T17) or chick cell lines (PBS-1)
Growth media	Serum-containing or animal-component media	Serum-free and animal-component- free media
Proteolytic enzyme	Porcine trypsin	Accutase, trypLE, or religiously slaughtered bovine trypsin
Microcarriers	Gelatin-coated microcarriers (FACT III, Cytodex 3, Cultispher S, Cultispher G)	Ionic microcarriers (Cytopore 2, Cytoline 2, Cytodex 1)
Stabilizer	Porcine or non-slaughtered bovine gelatin	Sugar alcohol (sorbitol, trehalose, inulin, etc.), religiously slaughtered bovine or fish gelatin.

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