Potency assay of the liquid Russell's viper (Daboia russelii siamensis) antivenom stored at different environment

Two methods of storing liquid antivenom (a) keeping it in a sand pot embedded in the ground and another (b) keeping antivenom containing sand pot in a lager sand pot and left in the house with daily and every third day watering of the sand was studied for 7 months covering the winter and hot summer months in Taungoo and Taungdwingyi respectively. Daily watering schedule kept the sand] -2C cooler than the every third day watering and maintained the temperature of the sand at 30-32C with a difference of 8-1 OC lower than the environmental temperature of 40C during the hot summer months. The efficacy of the antivenom stored in the first method with daily watering was found to be comparable to the control and superior to the antivenom stored in the first method with every third day watering and the anti venom stored in the second method with daily watering. It is recommended that liquid antivenom should be stored in a sand pot embedded in the ground with daily watering of the sand in places where no cold storage facility is available. This method of storage is simple, effective and inexpensive and could be carried out by the rural farmers.

Potency assay of antivenom: Batch to batch variation of neutralising efficacy of antivenom

Neutralisation of biological properties of Russell's viper venom (Thayawady) with 4 different batches of monospecific lyophilised antivenom manufactured by Myanmar Pharmaceutical Factory (batch DN 84560B exp. 2/90, DN 86608B exp. 4/92, DH 89652A exp. 9/94 and DD 90668B exp. 6/95) was assessed in rodents using WHO standard tests of neutralising activity. The amount of antivenom required to neutralise different biological properties of venom by different batches of antivenom varied from 2 to 50 times. Such variation of antivenom potency may explain failure of correction of some venom-induced effects seen in antivenom treated Russell's viper bite cases as well as variation in the composition of venom used as an immunogen. No quantitative differences in bands recognised by different antivenoms was observed in immunoblot. It is suggested that characterisation of widely pooled potent venoms to be used for antivenom production and potency assay of antivenom should be carried out routinely.

Potency assay of antivenom: Failure of Indian (serum institute) antivenom to neutralise Russell's viper (Daboia russelli siamensis) venom of Myanmar

Neutralisation of biological properties of Russell's viper (Daboia russelli siamensis) venom of Tharyarwady by a monospecific antivenom of Myanmar (DN 86608B ex. 4/92) and a polyspecific antivenom of Serum Institute of India (Sii) (batch 109 exp. 4/96) was carried out according to WHO standard tests of neutralising activity. Neutralising potency of Myanmar antivenom was superior to the Indian antivenom and the latter required 16-126 times more antivenom than the former in neutralising haemorrhagic, necrotic, lethality, defibrinogenating and capillary permeability increasing activities of the venom. In immunodiffusion and immunoblotting experiments fewer bands were detected in both. It is concluded that the Indian antivenom (Sii) will be less effective in treating Russell's viper bite cases of Myanmar.

Russell's viper toxoid: Pattern of antibody response following immunisation with toxoid in rabbits

A prospective study of the development and persistence of antibody following immunisation with Russell;s viper toxoid was carried out in rabbits. Two immunisation schedules, each consisting of 3 injections of the toxoid given at 0, 4 and 8 weeks and at 0, 6 and 30 weeks were studied. Booster injections were given at 24 and 60 weeks in the former and at 50 weeks in the latter. The pattern of antibody response of the two immunisation schedules was comparable. Peak antibody response was maintained for 8 weeks after the third injection. No antibody response was observed following boosting at 30, 50 and 60 weeks. Use of aged toxoid and timing of boosting may play an important role in induction of subsequent antibody responses.

Geographical variation of biological properties of Russell's viper venom: Bago Division

Biological properties of Russell's viper venom from four localities (Tharyarwaddy, Lepadan, Waw and Daike-U) of Bago Division were studied according to WHO recommended methods. SDS-PAGE electrophoresis of venoms were also performed. Biological properties of venom of young adults (61-90 cm) and adults (91-120 cm) of each locality were comparable except venom of young adult vipers of Tharyarwaddy possessed weak coagulant activity and that of adult vipers of Waw has potent haemorrhagic and necrotic activities.The adult viper venom of Tharyarwaddy was two times more potent in defibrinogenating and three times in capillary permeability activities than venom ofadult vipers of Lepadan. SDS-PAGE electrophoresis of venoms shows quantitative and qualitative differences in protein bands.

Potency assay of antivenom: neutralisation of biological properties of three Russell's viper venoms by a monospecific antivenom

Potency assay of a monovalent Russell's viper antivenom manufactured by Myanmar Pharmaceutical Factory (MPF) batch DN 866088 exp. 4/92 was assessed with Russell's viper venoms of Tharyarwady, Kungyankone and Daedaye in rodents using WHO standard tests of neutralising activity. There is variation in the amount of antivenom requires to neutralise individual biological property of three venoms and it is noteworthy that 4 times greater amount of antivenom is needed to neutralise haemorrhagic activity of Tharyarwady and defibrinogenating activenom of Kungyankone than the other two venoms. This variable performance of antivenom may be responsible for failure of correction of some venom induced effects seen in Russell's viper bite cases. It is suggested that a wider range of standard assays should be included in characterising the potency of antivenom.

Geographical variation of biological properties of Russell's viper (Doboia russelii siamensis) venom: Yangon division

Biological properties of Russell's viper (Daboia russelii siamensis) venoms collected from 5 localities (Htantabin, Kungyankone, Hmawbi, Hlegu and Indaing) of Yangon division were studied according to WHO recommended methods. Htantabin venom is the most potent among others. Both adult and young viper venoms of Htantabin possess potent lethality, capillary permeability increasing activity; necrotic and defibrinogenating activities inthe former and haemorrhagic in the latter. In contrast, adult venoms of Kungyankone has potent haemorrhagic and coagulant activities and the young has potent necortic and defibrinogenating activities. Such variation in venom properties may be responsible for variation in clinical pictures of Russell's viper bite cases seen within the same division and variable performance of antivenom.

Biological properties of Russell's viper venoms of upper and lower Myanmar

Biological properties and SDS-PAGE electrophoresis of Russell's viper venoms of Magwe (upper Myanmar) and Ayeyarwaddy divisions (lower Myanmar) were carried out following recommended techniques. Double diffusion and immunoblotting of venom and antivenom were also performed. There are inter and intradivisional variations in venom properties and in electrophoretic pattern. Biological properties of venom of Magwe and Ayeyarwaddy divisions are comparable except the former has weak procoagulant and potent defibrinogenating activities whereas the latter has potent procoagulant and weak defibrinogenating activities. Qualitative and quantitative differences in protein bands are recognized in precipitin reaction and in immunoblotting. These differences in venom properties and venom-antivenom reaction may account for variation in clinical pictures of Russell's viper bite cases of upper and lower Myanmar and variable performance of antivenom.

Geographical variation of biological properties of Russell's viper (Daboia Russelli Siamensis) venom: Magwe Division

Biological properties of Russell's viper venoms from two localities (Lokekogwa of Taungdwingyi township and Myehte) of Magwe division were studied in rodents according to WHO recommended techniques. SDS-PAGE electrophoresis of venoms was also carried out. Adult viper venom of Taungdwingyi possesses potent lethality, difibrinogenating, haemorrhagic and necrotic activities compared to young viper. Its lethality, procoagulant and capillary permeability increasing activities are more potent than Myehte venom, but the latter is slightly more haemorrhagic and necrotic than the former. SDS-PAGE electrophoresis of venoms shows qualitative and quantitative differences in protein bands. It may be concluded that adult Russell's viper venoms of Magwe division have weak procoagulant and potent defibrinogenating activities.

Biological properties of Russell's viper venoms of upper and lower Myanmar

Biological properties of Russell's viper venoms of Magwe (upper Myanmar) and Ayerawaddy (lower Myanmar) divisions were studied following recommended techniques. SDS-PAGE electrophoresis and immuno-blotting of venoms were also performed. Neutralisation of Taungdwingyi and Daedaye venoms by a monovalent antivenom was also tested. There are inter and intradivisional variation in venom properties and in electrophoretic pattern. Biological properties of venoms of Magwe and Ayerawaddy divisions are comparable however the latter has strong procoagulant activity. Qualitative and quantitative differences in protein bands are recognised in immunoblot. Two of 32 times greater amount of antivenom is needed to neutralise different biological properties of Taungdwingyi venom compared to that of Daedaye. These differences in venon properties and antivenom reactivity may account for variation in clinical pictures of Russell's viper bite cases of Myanmar and variable performance of antivenom.

Variation in biological properties of russell's viper venoms of Magwe division

Biological properties of Russell's viper venoms form two locallities (Kokekogwa, Taungdwingyi and Myehte) of Magwe division were studied in rodents according to WHO recommended techniques. SDS-PAGE electrophoresis of venoms was also carried out. Adult viper venom of Taungdwingyi possesses potent lethality and defibrinogenating activities and is more haemorrhagic and necrotic than venom of ypung viper. It's lethality, procoagulant and capillary permeability increasing activities are more potent than Myehte venom but the latter is slightly more haemorrhagic and necrotic than the former. In SDS-PAGE electrophoresis, qualitative and quantitative differences in protein bands were observed. It may be concluded that venoms of Magwe division have weak procoagulant and potent defibrinogenating activities and biological properties of venom of adult viper of Taungdwingyi is more potent than that of young viper.

Vitamin in biological properties of venoms from different localities of Ayeyarwady Division

Variation in biological properties and SDS-PAGE electrophoresis pattern of venoms from 5 localities (Nyaungdon, Danuphyu, Daedaye, Pyapon and Pantanaw) were studied according to the WHO recommended techniques. Snakes from each locality were grouped into 2 groups (<90 cm and >90 cm). Among mature (>90 cm) snakes, potent defibrinogenating, phospholipase, capillary permeabiligy increasing activities (CPI) and lethality were observed in Daedaye venom, necrotic in Pantanaw, haemorrhagic in Pyapon and coagulant in Nyaungdone. Immature snake (<90 cm) of Danuphyu venom possessed potent CPI with poor coagulant activities and Nyaungdone venom was the least necrotic among immature snakes. SDS-PAGE electrophoresis of venoms showed quantitative and qualitative changes of protein bands. In general biological properties of venoms of mature and immature snakes from the same locality are comparable except for a few differences.

Geographical variation of the biological properties of Russell's viper venom: A Prelliminary report

Venoms from 4 localities (Daik-U,Kungyankone, Htantabin and Htaukkyant) were studied by SDS-PAGE electrophoresis. Biological properties of venom such as lethality, haemorrhagic, necrotic, coagulant, defibrinogenating capillary permeability increasing and phospholipase activities were carried out according to WHO recommended techniques and standard methods. Venom from Daik-U locality was most lethal, haemorrhagic and necrotic compared to others. It possessed potent defibrinogenating, capillary permeability increasing and phospholipase (indirect haemolysis) activities as well. Kungyankone venom possessed potent coagulant and phospholipase activities with poor defibrinogenating and lethality. Htaukkyant and Htantabin venoms have similar biological properties except the former has poor phospholipase activity. SDS-PAGE electrophoresis and transblotting experiment of venoms showed quantitative difference in numbers of protein band among them. Geographicasl variation of venom may be responsible for the discrepancy in clinical features observed following Russell's viper bites in different localities.