UV-C LIGHT IN THE VENTILATOR UNIT OF INDIVIDUALLY VENTILATED CAGING SYSTEM

This invention claims Individually Ventilated Caging system (IVC system) for small animals comprising a Ventilation Unit (1) comprising an initial supply chamber (12) for taking external air inside the system for filtering and supplying to the cages in IVC system and an exhaust chamber (22) for exhausting the used air collected from the cages in the IVC system; the supply chamber and the exhaust chamber provided with filter/s (13),(14), (17), (18) for the incoming or outgoing/exhausting air; wherein the IVC system is characterized by devices additional to the filters for disinfecting incoming air and/or disinfecting out-going air exhausted from the cages. The additional devices comprise (a) UVC light (15), and/or (b) one or more electrostatic air filter/s and/or (3) an ionizer on supply and or exhaust side.

FIELD OF INVENTION

The present invention relates to the incorporation of UV-C light as additional source of protection against viruses not being filtered by supply and or exhaust HEPA (High-Efficiency Particulate Air) or ULPA (Ultra-Low Particulate Air) filters of the ventilator unit of IVC (Individually Ventilated Caging) system used for small animals like mice or guinea pigs.

BACKGROUND OF THE INVENTION

Ultraviolet (UV) light is a form of light that is invisible to the human eye. It occupies the portion of the electromagnetic spectrum between X-rays and visible light. The sun emits ultraviolet light; however, much of it is absorbed by the earth's ozone layer.1

UV light has three wavelength categories: UV-A, UV-B, and UV-C.

UV-C part of the ultraviolet light spectrum emits a high frequency of UV light that makes it extremely effective at killing bacteria, viruses, mold and other pathogens. Killing bacteria with UV light requires the use of germicidal wavelengths of 185-254 nanometers (nm).2

“Sanitizing with UV-C light has been a normal practice since the mid-20th century. In fact, the 1903 Nobel Prize in Medicine was awarded to Niels Finsen for using UV light to fight tuberculosis. Today, hospitals and laboratories use UV light to keep their facilities sterile, which means it perfect for sanitizing mobile devices, which are especially good at harboring and growing bacteria.”3

Viruses are obligate parasites that are biologically active only within their host. Viruses can be transmitted by various routes, including direct and indirect contact, vector transmission, and vehicle transmission. For deadly viruses such as Severe Acute Respiratory Syndrome (SARS) virus, influenza virus, and enterovirus, the vehicle transmission pathways include respiratory transmission by droplets and aerosols, as well as fecal-oral transmission via water, food, and environmental surfaces. To reduce infection risk from virus infection, control techniques for inactivating such viruses have been extensively researched (Jensen 1964; Gerba et al. 2002; Shin et al. 2003; Thurston-Enriquez et al. 2003). Among these control techniques, ultraviolet germicidal irradiation (UVGI) was demonstrated to be extremely efficient for virus inactivation (Jensen 1964; Galasso et al. 1965; Gerba et al. 2002; Nuanualsuwan et al. 2003; Thurston-Enriquez et al. 2003).The mechanisms of UVGI on microbes are uniquely vulnerable to light at wavelengths at or near 253.7 nm, because the maximum absorption wavelength of aDNA molecule is 260 nm. The pyrimidine of DNA base can strongly absorb UV light. After irradiation, the DNA sequence where pyrimidine and pyrimidine link can form pyrimidine dimers. These dimers can change the DNA double helix structure and interfere with DNA duplication, as well as lead to the destruction of the replicate ability of cells and thus render the cells non-infectious (Brickner et al. 2003).4

In the field of laboratory animal management, in particular with small animals such as mice or guinea pigs, cages are used in particular sealed cage suitable to be connected to a ventilation system. Cages are usually housed side by side and stacked on shelves or stacked in the cabinet constructed for this purpose. Environment inside these cages must be tightly controlled to prevent contamination of the animals by the external environment and/or contamination of the environment and humans by the animals. Individually Ventilated Caging (IVC) systems are widely used for housing laboratory animals that enable a plurality of such animal cages to be arranged in an industrious and efficient manner. These systems are designed for providing a highly consistent environment across all cages.

Prior art IVC system comprises of Ventilat or unit for air supply and exhaust or for exhaust only; an IVC Cage or cages and Racks or cabinets to hold the IVC Cage or Cages. Ventilator unit works to supply High-Efficiency Particulate Air (HEPA) or Ultra-Low Particulate filtered Air (ULPA) using the fan or blower to the IVC Cage and exhaust air from the IVC Cage through the distribution network of the rack/cabinet connections. In an alternative system, also known as EVC (Exhaust Ventilated Caging System), the cages take in air directly from the room in which they are held in racks, the Ventilator unit in such cases works only to exhaust the air from the cages to outside environment.

Each ventilator unit is fitted with blower or fan, pre-filters and HEPA or ULPA filters on supply and or exhaust side so that HEPA or UPLA filtered air can be supplied to the IVC Cage and or exhausted air from the IVC Cage can be HEPA or ULPA filtered before releasing to the external environment.

HEPA filters can capture at least 99.97% of particles with a diameter greater than or equal to 0.3 μm. Ultra-low particulate (or sometimes “penetration”) air (ULPA) filters are closely related to HEPA filters but are even more efficient in their filtration capability. ULPA filters are specified to remove 99.999% of contaminants 0.12 μm or larger in diameter.

Thus the Ventilator unit of IVC Caging System takes in ambient air and supplies HEPA or ULPA filtered air to the IVC Cage and or exhaust the air inside the IVC Cage and release the HEPA or ULPA filtered air to the external environment.

The purpose of the ventilator unit is to provide filtered air free from viruses, allergens, bacteria or pathogens so as to protect the animal inside IVC Cage and also if any infection model is created in the animal within the IVC Cage then release the exhausted air from the IVC cage by proper filtration so that no viruses, allergens, bacteria or pathogens are released in the external environment.

Although HEPA filters are high in efficiency, yet they have efficiency for size range 0.1 to 0.3 micron only. Many viruses have size in the range of 0.004 to 0.3 μ which would make access though the filtered air of Ventilator unit of IVC Caging system to the IVC Cage leading to a potential threat to the animal in the IVC Cage or release of such virus from IVC Cage to the external environment during the exhaust creating potential threat to the humans.

Hence, there was a need of improved individually ventilated caging system.

SUMMARY OF INVENTION

This invention claims Individually Ventilated Caging system (IVC system) for small animals comprising a Ventilation Unit1comprising an initial supply chamber12for taking external air inside the system for filtering and supplying to the cages in IVC system and an exhaust chamber22for exhausting the used air collected from the cages in the IVC system; the supply chamber and the exhaust chamber provided with filter/s13,14,17,18for the incoming or outgoing/exhausting air; wherein the IVC system is characterized by devices additional to the filters for disinfecting incoming air and/or disinfecting out-going air exhausted from the cages. The devices additional to the filters for disinfecting incoming air and/or disinfecting out-going air exhausted from the cages comprises (a) UV C light15, and/or (b) one or more electrostatic air filter/s and/or (3) an ionizer on supply and or exhaust side.

The IVC system according to this invention comprises a Ventilator unit1which has supply section and/or exhaust section, HEPA or ULPA filters provided in supply section and exhaust section for filtering air passing through these sections to supply the UV-C light15treated filtered air through supply ports3and4to the IVC Cages placed on the Rack10through a supply distribution network8connected to ventilator unit1through a suitable flexible or non flexible pipe30a.

The IVC system according to this invention also comprises an exhaust distribution network9of the rack for collecting and return of the used air from the cages back to the Ventilator unit1through an exhaust port6of the Ventilator Unit1, the exhaust distribution network9, the exhaust port being interconnected with the exhaust distribution network9through a flexible or non flexible pipe30b, the exhaust air brought back to Ventilation Unit1being treated with UVC light19and being filtered through HEPA- or ULPA-filtration; and return to the external environment though exhaust port7of the Ventilator unit1.

The Ventilator unit1comprises a Control Panel with display2where different operational parameters are displayed.

The IVC system also comprises one or more Racks10for holding IVC Cages are provided each being supplied with the UV-C light15treated filtered air through additional supply ports. Parameters displayed on the Control Panel consist of one or more selected from the group consisting of air changes per hour, positive or negative pressure modes, number of cages, temperature, relative humidity, ammonia and other environmental parameters.

The Ventilator unit1has upper half as a supply section and lower half as exhaust section. The supply section comprises one or more supply blower or fan12, duct of supply blower23, supply side HEPA or supply side ULPA filter13, supply side pre-filter14, one or more UV-C lights15, initial supply chamber21and final supply chamber25. The exhaust section comprises one or more exhaust blower or fan16, duct of exhaust blower24, exhaust side HEPA or exhaust side ULPA filter17, exhaust side pre-filter18, one or more UV-C light19and initial exhaust chamber22.

The Ventilator unit1has filtered air supply ports on supply side labeled as supply port no.3and4, each one connecting to separate rack units10for holding the IVC Cage in the supply distribution Network8; and exhaust air outlet ports on exhaust side labeled as exhaust port no.5and6coming from two separate rack units10for connecting with the exhaust distribution network9of one or more rack for holding the IVC Cages11.

The Ventilator unit1comprises an air inlet20for taking external air in for filtration and circulation. Supply blower or fan12takes the air from the external environment through the air inlet20for filtration, treatment with UV-C light15and supplies to the IVC Cages. The initial supply chamber21is fitted with one or more UV-C light15either above the filters or below the prefilter or between pre-filter14and HEPA filter or ULPA filter13or at any two locations mentioned above or at all the three locations mentioned herein,

The Ventilator unit1also comprises an air supply port on supply side as supply port nos.3and4for connecting with the rack10that holds the IVC Cages. The initial exhaust chamber22is fitted with one or more UV-C light19. The UV-C light19may be fitted before or after the filter or between pre-filter18and HEPA filter or ULPA filter17or at any two locations mentioned above or at all the three locations mentioned herein. In the initial exhaust chamber22the air is passed through supply pre-filter14and supply side HEPA or supply side ULPA filter13for further removing the particles in the air stream. This filtered air then passes through the duct of supply blower23and through the supply blower or fan12and then to the Final supply chamber25. The filtered air in the final supply chamber25then passes through the supply ports3and or4or more ports in case more racks are connected to the ventilator Unit1to the supply distribution network8of the rack10for holding IVC Cage and eventually to the IVC Cages11loaded on the rack10. The air from the cage is exhausted, filtered and treated with UV-C light in the exhaust section of the ventilator unit1for disinfection and the treated air is released to the external environment from the outlet port7.

The IVC system as claimed in claim5wherein the wattage of UV-C15and UV-C19lights is selected to provide disinfection of the volume of air that is drawn in respective supply chamber and exhaust chamber and within residence time of the air within these chambers.

Each IVC Cage11has one cage air supply valve27and/or cage air exhaust valve26situated either on cage bottom28or alternatively they can also be situated on cage lid29. Cage lid29and cage bottom28are connected together so as to form airtight connection.

Air from the rack for holding IVC Cage10, passes through the supply distribution network8to the cage air supply valve27of the IVC Cage11, filtered and UV-C light treated air then reaches inside the IVC Cage11providing ventilation for the animals within the IVC Cage11. Air inside the IVC Cage11is then exhausted from the cage air exhaust valve26using the Exhaust distribution network9to the Exhaust port5and or6of the Ventilator1due to the suction created by Exhaust blower or fan16.

The exhausted air first reaches for treatment and filtration to initial exhaust chamber22fitted with one or more UV-C light19, pre-filter18and exhaust side HEPA or exhaust side ULPA filter17. This air after treatment with UV-C light19and filters and then passes through the duct of exhaust blower24, to fan16and exhaust port7and then eventually released to the external environment by suitable means.

The IVC system is designed for small animals which comprise, without limitation, mice, guinea pigs and the like.

DETAILED DESCRIPTION OF THE INVENTION

A significant body of scientific research like Bintsis et al. 20005, Yaun et al. 20046, Do-Kyun Kim et al 20187, Lyndon 19778, Walker et al 20079has proven UV-C light's ability to inactivate an extensive list of pathogenic bacteria, viruses and protozoa.

In one aspect this invention relates to Individually Ventilated Caging system (IVC) for small animals characterized by providing devices additional to the filters for disinfecting incoming air and/or disinfecting out-going air exhausted from the cages. The devices additional to the filters for disinfecting incoming air and/or disinfecting out-going air exhausted from the cages comprises (a) UV C light15, and/or (b) one or more electrostatic air filter/s and/or (3) an ionizer on supply and or exhaust side. The UV-C light may be fitted either above the filters or below the prefilter or between pre-filter14/18and HEPA filter or ULPA filter13/17or at any two locations mentioned above or at all the three locations mentioned herein.

This feature provides additional protection to the caged animal by killing the bacteria and/or viruses in the air before supplying to the IVC Cage. In another aspect of this invention, providing UV-C light on the exhaust side of HEPA or ULPA filter provides additional protection to the external environment by killing the bacteria and/or viruses in the exhausted air from the cage before releasing to the external environment.

Addition of UV-C Light source in supply and or exhaust side also provide additional protection to the ventilator's inside area by killing the bacteria, allergens or viruses already gathered on sor other nearby areas within the range of UV-C light source..

BRIEF DESCRIPTION OF FIGURES AND LEGENDS

FIG.1schematically shows complete individually ventilated caging (IVC) system comprising Ventilator unit1, Rack10for holding IVC Cages, IVC Cage11. UVC light treated, HEPA or ULPA filtered air is supplied by Ventilator unit to the IVC Cages placed on the Rack for holding IVC Cages through the Supply port3of the Ventilator unit1and Supply distribution network8of the rack which are interconnected through suitable flexible or non flexible pipe30a. Similarly, the air from the cage is returned through the Exhaust distribution network9of the rack and exhaust port6of the Ventilator which are inter connected through suitable flexible or non flexible pipe30bback to the Ventilator unit1where it is treated with UVC light either before and or after HEPA or ULPA filtration; and is returned to the external environment though exhaust port7(shown inFIG.2) of the Ventilator unit1. More similar racks can be connected to same Ventilator unit1depending on the blower capacity. As an illustration one more rack is shown connected to same Ventilator unit1inFIG.1. For each such additional rack10that may be connected to Ventilator unit1, system features are replicated mutatis mutandis for such additional racks. Ventilator unit1has a Control panel with display2where different parameters like air changes per hour, pressure mode etc. can be displayed.

FIGS.2(a) and2(b)schematically shows cutaway view of Ventilator unit1.

Ventilator unit1has supply section and/or exhaust section. Supply section comprises one or more Supply blower or fan12, Duct of supply blower23, supply side HEPA or supply side ULPA filter13, supply side pre-filter14, one or more UV-C lights15, Initial supply chamber21and Final supply chamber25. Similarly exhaust section comprises one or more Exhaust blower or fan16, Duct of exhaust blower24, Exhaust HEPA or ULPA filter17, Exhaust pre-filter18, one or more UV-C light19and Initial exhaust chamber22.

FIG.3shows schematic diagram of Ventilator unit showing the air inlet20for taking external air: Ventilator unit (1) has air inlet20for taking external air in for filtration and circulation. Supply blower or fan12, shown inFIG.2(a)andFIG.2(b), takes the air from the external environment through the air inlet20and this air is further processed for filtration and supplied to the IVC Cages.

FIG.4shows top view of Ventilator unit showing supply port3and4and exhaust port7: Ventilator unit1has air supply port on supply side as Supply port no.3and4for connecting with the Rack10for Holding the IVC Cage . Air from the cage is exhausted and filtered in the exhaust section of the Ventilator unit1and the filtered air is released to the external environment from the outlet port7.

Each IVC Cage11has one Cage air supply valve27and/or Cage air exhaust valve26situated either on Cage bottom28or alternatively they can also be situated on Cage lid29. Cage lid29and cage bottom28are connected together so as to form airtight connection.

To each Ventilator unit1, depending on the capacity of the blower, more than one units of racks10can be attached and each one being supplied with filtered air supplying line and or exhaust line. Ventilator unit1has air supply port on supply side as Supply port no.3and4, or more depending on number of racks attached to the Ventilator unit1, for connecting with the Supply Distribution Network8for one or more Rack10. Similarly, Ventilator unit1has exhaust air outlet ports on exhaust side as Exhaust port no.5and6for connecting with the Exhaust Distribution Network9for one or more Rack/s10for Holding the IVC Cage.

Ventilator unit1has air inlet20(FIG.3) for taking external air in for filtration and circulation. Supply blower or fan12(FIG.2) takes the air from the external environment through the air inlet20and this air enters in the Initial supply chamber21. Initial supply chamber21is fitted with one or more UV-C light15either above the filters or below the prefilter or between pre-filter14and HEPA filter or ULPA filter13or at any two locations mentioned above or at all the three locations mentioned herein. The wattage of UV-C15light shall differ from location to location depending upon the microbial load of samples of input air that is drawn in and of the outgoing air and adjusting the wattage to a point wherein 100% preferably or a lower level that is considered as acceptable for sterility/disinfection of the outcoming air is attained.

In one embodiment of the Ventilator unit, the air flow rate on the supply side or exhaust side is not more than 0.9 cfm whereas the intensity of 254 nm UV radiation from the two light sources of 12 W light was found to be more than 1450 μW/cm2. The UV-C light15acts as germicidal lamp and kills the bacteria, viruses, mold and other pathogens in the stream of the air taken in by the Supply blower or fan12. This air is treated with UV-C light15either before or after filtration or at both instances. Filtration may be done in many different ways. Most convenient method is by passing through supply side Pre-filter14and supply side HEPA or ULPA filter13for further removing the particles in the air stream. This filtered air then passes through the Duct of supply blower23and through the Supply blower or fan12and then to the Final supply chamber25. Filtered air in the Final supply chamber25then passes through the Supply port3and or4to the Supply distribution network8of the Rack10for holding IVC Cage and eventually to the IVC Cages11loaded on the Rack10. The UV C light can be fitted at any position below or above or at both locations with respect to HEPA/ULPA filter/s of the supply section.

Ventilator unit1(FIG.2) has supply section (upper half) and exhaust section (lower half). Supply section comprises one or more Supply blower or fan12, Duct of supply blower23, one or more supply side HEPA or ULPA filter of same or different types13, one or more supply side pre-filter of same of different types including active carbon filters for odor removal14, one or more UV-C light15, Initial supply chamber21(supplied with incoming air from environment through air inlet20) and Final supply chamber25. Similarly exhaust section comprises one or more Exhaust blower or fan16, duct of exhaust blower24, one or more Exhaust HEPA or ULPA filter of same or different types17, one or more Exhaust pre-filter18of same or different types including active carbon filters for odor removal, one or more UV-C light19either below or above the filter or at both places and Initial exhaust chamber22.

Ventilator unit1has filtered air supply ports on supply side labeled as supply port no.3and4, each one connecting to separate rack units10for holding the IVC Cage in the Supply Distribution Network8. Similarly, ventilator unit1has exhaust air outlet ports on exhaust side labeled as exhaust port no.5and6(shown inFIG.1) coming from two separate rack units for connecting with the exhaust distribution network9of one or more rack for Holding the IVC Cage10.

Each IVC Cage11(FIG.5) has one Cage air supply valve27and Cage air exhaust valve26situated either on Cage bottom28or Cage lid29. Air from the Rack for holding IVC Cage10, passes through the Supply distribution network8to the Cage air supply valve27of the IVC Cage11. Filtered air then reaches inside the IVC Cage11providing ventilation for the animals within the IVC Cage11.

Air inside the IVC Cage11is then exhausted from the Cage air exhaust valve26using the Exhaust distribution network9to the Exhaust port5and or6of the Ventilator1due to the suction created by Exhaust blower or fan16. The exhausted air first reaches to initial exhaust chamber22fitted with one or more UV-C light19. The UV-C light19may be fitted before or after the filter or between pre-filter18and HEPA filter or ULPA filter17or at any two locations mentioned above or at all the three locations mentioned herein. The wattage of UV-C19light is selected to provide complete disinfection of the volume of air that is being exhausted and within its residence time in the air exhaust side. The UV-C light19acts as germicidal lamp and kills the bacteria, viruses, mold and other pathogens in the stream of the air that is taken back from the cage and rack system.. UV-C light19acts as a germicidal lamp killing the bacteria, viruses, mold and other pathogens in the exhausted air taken back from the cage. This air already treated with UV-C light19then passes through Exhaust Pre-filter18and Exhaust HEPA or ULPA filter17for further filtration. The treatment of air by UV-C light19can be either before or after filtration or at both locations This filtered exhausted air then passes through the duct of Exhaust blower24, to fan16and exhaust port7and then eventually released to the external environment by suitable means. The UV C light can be fitted at any position below or above or at both locations with respect to HEPA/ULPA filter/s of the exhaust section.

Ventilator unit1has control panel2where different parameters like air changes per hour (ACPH), positive or negative pressure modes and number of cages can be set as well as many different parameters like temperature, relative humidity, ammonia etc. can be monitored and displayed.

REFERENCES